diff --git a/apple/OmnivoreKit/Sources/App/Views/Registration/RegistrationView.swift b/apple/OmnivoreKit/Sources/App/Views/Registration/RegistrationView.swift index db6250caf..c618d34b4 100644 --- a/apple/OmnivoreKit/Sources/App/Views/Registration/RegistrationView.swift +++ b/apple/OmnivoreKit/Sources/App/Views/Registration/RegistrationView.swift @@ -59,7 +59,8 @@ import Views } func handleGoogleAuth(authenticator: Authenticator) async { - let googleAuthResponse = await authenticator.handleGoogleAuth() + let presentingVC = presentingViewController() + let googleAuthResponse = await authenticator.handleGoogleAuth(presentingVC: presentingVC) switch googleAuthResponse { case let .loginError(error): @@ -71,3 +72,15 @@ import Views } } } + +@MainActor private func presentingViewController() -> PlatformViewController? { + #if os(iOS) + let scene = UIApplication.shared.connectedScenes.first as? UIWindowScene + return scene?.windows + .filter(\.isKeyWindow) + .first? + .rootViewController + #elseif os(macOS) + return NSApplication.shared.windows.first + #endif +} diff --git a/apple/OmnivoreKit/Sources/Services/Authentication/GoogleAuth.swift b/apple/OmnivoreKit/Sources/Services/Authentication/GoogleAuth.swift index 2fa15f0f2..89324e140 100644 --- a/apple/OmnivoreKit/Sources/Services/Authentication/GoogleAuth.swift +++ b/apple/OmnivoreKit/Sources/Services/Authentication/GoogleAuth.swift @@ -10,9 +10,9 @@ public enum GoogleAuthResponse { } extension Authenticator { - public func handleGoogleAuth() async -> GoogleAuthResponse { + public func handleGoogleAuth(presentingVC: PlatformViewController?) async -> GoogleAuthResponse { let idToken = await withCheckedContinuation { continuation in - googleSignIn { continuation.resume(returning: $0) } + googleSignIn(presenting: presentingVC) { continuation.resume(returning: $0) } } guard let idToken = idToken else { return .loginError(error: .unauthorized) } @@ -50,13 +50,7 @@ extension Authenticator { } } - func googleSignIn(completion: @escaping (String?) -> Void) { - #if os(iOS) - let presenting = presentingViewController() - #else - let presenting = NSApplication.shared.windows.first - #endif - + func googleSignIn(presenting: PlatformViewController?, completion: @escaping (String?) -> Void) { guard let presenting = presenting else { completion(nil) return @@ -82,15 +76,3 @@ extension Authenticator { } } } - -private func presentingViewController() -> PlatformViewController? { - #if os(iOS) - let scene = UIApplication.shared.connectedScenes.first as? UIWindowScene - return scene?.windows - .filter(\.isKeyWindow) - .first? - .rootViewController - #elseif os(macOS) - return nil - #endif -} diff --git a/packages/api/package.json b/packages/api/package.json index 9060f0641..0f1b60eba 100644 --- a/packages/api/package.json +++ b/packages/api/package.json @@ -71,6 +71,7 @@ "graphql-shield": "^7.5.0", "highlightjs": "^9.16.2", "html-entities": "^2.3.2", + "image-size": "^1.0.2", "intercom-client": "^3.1.4", "ioredis": "^5.3.2", "jsonwebtoken": "^8.5.1", @@ -155,4 +156,4 @@ "volta": { "extends": "../../package.json" } -} \ No newline at end of file +} diff --git a/packages/api/src/entity/subscription.ts b/packages/api/src/entity/subscription.ts index e1b8da23b..fd17d8d73 100644 --- a/packages/api/src/entity/subscription.ts +++ b/packages/api/src/entity/subscription.ts @@ -7,12 +7,22 @@ import { PrimaryGeneratedColumn, UpdateDateColumn, } from 'typeorm' -import { SubscriptionStatus, SubscriptionType } from '../generated/graphql' import { NewsletterEmail } from './newsletter_email' import { User } from './user' export const DEFAULT_SUBSCRIPTION_FOLDER = 'following' +export enum SubscriptionStatus { + Active = 'ACTIVE', + Deleted = 'DELETED', + Unsubscribed = 'UNSUBSCRIBED', +} + +export enum SubscriptionType { + Newsletter = 'NEWSLETTER', + Rss = 'RSS', +} + @Entity({ name: 'subscriptions' }) export class Subscription { @PrimaryGeneratedColumn('uuid') @@ -59,7 +69,7 @@ export class Subscription { count!: number @Column('timestamp', { nullable: true }) - lastFetchedAt?: Date | null + mostRecentItemDate?: Date | null @Column('text', { nullable: true }) lastFetchedChecksum?: string | null @@ -73,6 +83,12 @@ export class Subscription { @Column('timestamp', { nullable: true }) scheduledAt?: Date | null + @Column('timestamp', { nullable: true }) + refreshedAt?: Date | null + + @Column('timestamp', { nullable: true }) + failedAt?: Date | null + @Column('boolean') isPrivate?: boolean | null diff --git a/packages/api/src/events/reports/content_display_report_created.ts b/packages/api/src/events/reports/content_display_report_created.ts index d89dcfc22..4345e0601 100644 --- a/packages/api/src/events/reports/content_display_report_created.ts +++ b/packages/api/src/events/reports/content_display_report_created.ts @@ -23,16 +23,17 @@ export class ContentDisplayReportSubscriber ${report.user.id} for URL: ${report.originalUrl} ${report.reportComment}` - logger.info(message) - - if (!env.dev.isLocal) { - // If we are in the local environment, just log a message, otherwise email the report - await sendEmail({ - to: env.sender.feedback, - subject: 'New content display report', - text: message, - from: env.sender.message, - }) + // If we are in the local environment, just log a message, otherwise email the report + if (env.dev.isLocal) { + logger.info(message) + return } + + await sendEmail({ + to: env.sender.feedback, + subject: 'New content display report', + text: message, + from: env.sender.message, + }) } } diff --git a/packages/api/src/generated/graphql.ts b/packages/api/src/generated/graphql.ts index c68e340ee..9d908a941 100644 --- a/packages/api/src/generated/graphql.ts +++ b/packages/api/src/generated/graphql.ts @@ -2283,8 +2283,11 @@ export type SaveFileInput = { clientRequestId: Scalars['ID']; folder?: InputMaybe; labels?: InputMaybe>; + publishedAt?: InputMaybe; + savedAt?: InputMaybe; source: Scalars['String']; state?: InputMaybe; + subscription?: InputMaybe; uploadFileId: Scalars['ID']; url: Scalars['String']; }; @@ -2833,14 +2836,17 @@ export type Subscription = { count: Scalars['Int']; createdAt: Scalars['Date']; description?: Maybe; + failedAt?: Maybe; fetchContent: Scalars['Boolean']; folder: Scalars['String']; icon?: Maybe; id: Scalars['ID']; isPrivate?: Maybe; lastFetchedAt?: Maybe; + mostRecentItemDate?: Maybe; name: Scalars['String']; newsletterEmail?: Maybe; + refreshedAt?: Maybe; status: SubscriptionStatus; type: SubscriptionType; unsubscribeHttpUrl?: Maybe; @@ -3205,13 +3211,15 @@ export enum UpdateSubscriptionErrorCode { export type UpdateSubscriptionInput = { autoAddToLibrary?: InputMaybe; description?: InputMaybe; + failedAt?: InputMaybe; fetchContent?: InputMaybe; folder?: InputMaybe; id: Scalars['ID']; isPrivate?: InputMaybe; - lastFetchedAt?: InputMaybe; lastFetchedChecksum?: InputMaybe; + mostRecentItemDate?: InputMaybe; name?: InputMaybe; + refreshedAt?: InputMaybe; scheduledAt?: InputMaybe; status?: InputMaybe; }; @@ -6186,14 +6194,17 @@ export type SubscriptionResolvers; createdAt?: SubscriptionResolver; description?: SubscriptionResolver, "description", ParentType, ContextType>; + failedAt?: SubscriptionResolver, "failedAt", ParentType, ContextType>; fetchContent?: SubscriptionResolver; folder?: SubscriptionResolver; icon?: SubscriptionResolver, "icon", ParentType, ContextType>; id?: SubscriptionResolver; isPrivate?: SubscriptionResolver, "isPrivate", ParentType, ContextType>; lastFetchedAt?: SubscriptionResolver, "lastFetchedAt", ParentType, ContextType>; + mostRecentItemDate?: SubscriptionResolver, "mostRecentItemDate", ParentType, ContextType>; name?: SubscriptionResolver; newsletterEmail?: SubscriptionResolver, "newsletterEmail", ParentType, ContextType>; + refreshedAt?: SubscriptionResolver, "refreshedAt", ParentType, ContextType>; status?: SubscriptionResolver; type?: SubscriptionResolver; unsubscribeHttpUrl?: SubscriptionResolver, "unsubscribeHttpUrl", ParentType, ContextType>; diff --git a/packages/api/src/generated/schema.graphql b/packages/api/src/generated/schema.graphql index 5c2431d8a..2df4f681e 100644 --- a/packages/api/src/generated/schema.graphql +++ b/packages/api/src/generated/schema.graphql @@ -1718,8 +1718,11 @@ input SaveFileInput { clientRequestId: ID! folder: String labels: [CreateLabelInput!] + publishedAt: Date + savedAt: Date source: String! state: ArticleSavingRequestStatus + subscription: String uploadFileId: ID! url: String! } @@ -2229,14 +2232,17 @@ type Subscription { count: Int! createdAt: Date! description: String + failedAt: Date fetchContent: Boolean! folder: String! icon: String id: ID! isPrivate: Boolean lastFetchedAt: Date + mostRecentItemDate: Date name: String! newsletterEmail: String + refreshedAt: Date status: SubscriptionStatus! type: SubscriptionType! unsubscribeHttpUrl: String @@ -2572,13 +2578,15 @@ enum UpdateSubscriptionErrorCode { input UpdateSubscriptionInput { autoAddToLibrary: Boolean description: String + failedAt: Date fetchContent: Boolean folder: String id: ID! isPrivate: Boolean - lastFetchedAt: Date lastFetchedChecksum: String + mostRecentItemDate: Date name: String + refreshedAt: Date scheduledAt: Date status: SubscriptionStatus } diff --git a/packages/api/src/jobs/find_thumbnail.ts b/packages/api/src/jobs/find_thumbnail.ts new file mode 100644 index 000000000..85427dafc --- /dev/null +++ b/packages/api/src/jobs/find_thumbnail.ts @@ -0,0 +1,170 @@ +import axios, { AxiosResponse } from 'axios' +import sizeOf from 'image-size' +import { parseHTML } from 'linkedom' +import { + findLibraryItemById, + updateLibraryItem, +} from '../services/library_item' +import { createThumbnailUrl } from '../utils/imageproxy' +import { logger } from '../utils/logger' + +interface Data { + libraryItemId: string + userId: string +} + +interface ImageSize { + src: string + width: number + height: number +} + +export const THUMBNAIL_JOB = 'find-thumbnail' + +const fetchImage = async (url: string): Promise => { + logger.info('fetching image', url) + try { + // get image file by url + return await axios.get(url, { + responseType: 'arraybuffer', + timeout: 10000, // 10s + maxContentLength: 20000000, // 20mb + }) + } catch (e) { + logger.error('fetch image error', e) + return null + } +} + +const getImageSize = async (src: string): Promise => { + try { + const response = await fetchImage(src) + if (!response) { + return null + } + + // eslint-disable-next-line @typescript-eslint/no-unsafe-argument + const buffer = Buffer.from(response.data, 'binary') + + // get image size + const { width, height } = sizeOf(buffer) + + if (!width || !height) { + return null + } + + return { + src, + width, + height, + } + } catch (e) { + logger.error(e) + return null + } +} + +export const fetchAllImageSizes = async (content: string) => { + const dom = parseHTML(content).document + + // fetch all images by src and get their sizes + const images = dom.querySelectorAll('img[src]') + if (!images || images.length === 0) { + return [] + } + + return Promise.all( + Array.from(images).map((image) => { + const src = image.getAttribute('src') + if (!src) { + return null + } + + return getImageSize(src) + }) + ) +} + +// credit: https://github.com/reddit-archive/reddit/blob/753b17407e9a9dca09558526805922de24133d53/r2/r2/lib/media.py#L706 +export const _findThumbnail = (imagesSizes: (ImageSize | null)[]) => { + // find the largest and squarest image as the thumbnail + let thumbnail = '' + let largestArea = 0 + for (const imageSize of Array.from(imagesSizes)) { + if (!imageSize) { + continue + } + + let area = imageSize.width * imageSize.height + + // ignore small images + if (area < 5000) { + continue + } + + // penalize excessively long/wide images + const ratio = + Math.max(imageSize.width, imageSize.height) / + Math.min(imageSize.width, imageSize.height) + if (ratio > 1.5) { + area /= ratio * 2 + } + + // penalize images with "sprite" in their name + if (imageSize.src.toLowerCase().includes('sprite')) { + area /= 10 + } + + if (area > largestArea) { + largestArea = area + thumbnail = imageSize.src + } + } + + return thumbnail +} + +export const findThumbnail = async (data: Data) => { + const { libraryItemId, userId } = data + + const item = await findLibraryItemById(libraryItemId, userId) + if (!item) { + logger.info('page not found') + return false + } + + const thumbnail = item.thumbnail + if (thumbnail) { + const proxyUrl = createThumbnailUrl(thumbnail) + // pre-cache thumbnail first if exists + const image = await fetchImage(proxyUrl) + if (!image) { + logger.info('thumbnail image not found') + item.thumbnail = undefined + } + } + + logger.info('pre-caching all images...') + // pre-cache all images in the content and get their sizes + const imageSizes = await fetchAllImageSizes(item.readableContent) + // find thumbnail from all images if thumbnail not set + if (!item.thumbnail && imageSizes.length > 0) { + const thumbnail = _findThumbnail(imageSizes) + if (!thumbnail) { + logger.info('no thumbnail found from content') + return false + } + + // update page with thumbnail + await updateLibraryItem( + libraryItemId, + { + thumbnail, + }, + userId + ) + logger.info(`thumbnail updated: ${thumbnail}`) + } + + return true +} diff --git a/packages/api/src/jobs/rss/refreshAllFeeds.ts b/packages/api/src/jobs/rss/refreshAllFeeds.ts index 6a78d8596..5a50e41ce 100644 --- a/packages/api/src/jobs/rss/refreshAllFeeds.ts +++ b/packages/api/src/jobs/rss/refreshAllFeeds.ts @@ -1,11 +1,11 @@ -import { Job, Queue } from 'bullmq' +import { Job } from 'bullmq' import { DataSource } from 'typeorm' -import { QUEUE_NAME, getBackendQueue } from '../../queue-processor' -import { redisDataSource } from '../../redis_data_source' +import { v4 as uuid } from 'uuid' +import { getBackendQueue } from '../../queue-processor' +import { validateUrl } from '../../services/create_page_save_request' import { RssSubscriptionGroup } from '../../utils/createTask' import { stringToHash } from '../../utils/helpers' -import { validateUrl } from '../../services/create_page_save_request' -import { v4 as uuid } from 'uuid' +import { logger } from '../../utils/logger' export type RSSRefreshContext = { type: 'all' | 'user-added' @@ -21,39 +21,44 @@ export const refreshAllFeeds = async (db: DataSource): Promise => { } as RSSRefreshContext const subscriptionGroups = (await db.createEntityManager().query( ` - SELECT - url, - ARRAY_AGG(id) AS "subscriptionIds", - ARRAY_AGG(user_id) AS "userIds", - ARRAY_AGG(last_fetched_at) AS "fetchedDates", - ARRAY_AGG(coalesce(scheduled_at, NOW())) AS "scheduledDates", - ARRAY_AGG(last_fetched_checksum) AS checksums, - ARRAY_AGG(fetch_content) AS "fetchContents", - ARRAY_AGG(coalesce(folder, $3)) AS folders - FROM - omnivore.subscriptions - WHERE - type = $1 - AND status = $2 - AND (scheduled_at <= NOW() OR scheduled_at IS NULL) - GROUP BY - url - `, - ['RSS', 'ACTIVE', 'following'] + SELECT + url, + ARRAY_AGG(s.id) AS "subscriptionIds", + ARRAY_AGG(s.user_id) AS "userIds", + ARRAY_AGG(s.most_recent_item_date) AS "mostRecentItemDates", + ARRAY_AGG(coalesce(s.scheduled_at, NOW())) AS "scheduledDates", + ARRAY_AGG(s.last_fetched_checksum) AS checksums, + ARRAY_AGG(s.fetch_content) AS "fetchContents", + ARRAY_AGG(coalesce(s.folder, $3)) AS folders + FROM + omnivore.subscriptions s + INNER JOIN + omnivore.user u ON u.id = s.user_id + WHERE + s.type = $1 + AND s.status = $2 + AND (s.scheduled_at <= NOW() OR s.scheduled_at IS NULL) + AND u.status = $4 + GROUP BY + s.url + `, + ['RSS', 'ACTIVE', 'following', 'ACTIVE'] )) as RssSubscriptionGroup[] - console.log(`rss: checking ${subscriptionGroups.length}`, { refreshContext }) + logger.info(`rss: checking ${subscriptionGroups.length}`, { + refreshContext, + }) for (const group of subscriptionGroups) { try { await updateSubscriptionGroup(group, refreshContext) } catch (err) { // we don't want to fail the whole job if one subscription group fails - console.error('error updating subscription group') + logger.error('error updating subscription group') } } const finishTime = new Date() - console.log( + logger.info( `rss: finished queuing subscription groups at ${finishTime.toISOString()}`, { refreshContext, @@ -70,18 +75,18 @@ const updateSubscriptionGroup = async ( let feedURL = group.url const userList = JSON.stringify(group.userIds.sort()) if (!feedURL) { - console.error('no url for feed group', group) + logger.error('no url for feed group', group) return } if (!userList) { - console.error('no userlist for feed group', group) + logger.error('no userlist for feed group', group) return } try { feedURL = validateUrl(feedURL).toString() } catch (err) { - console.log('not refreshing invalid feed url: ', { feedURL }) + logger.error(`not refreshing invalid feed url: ${feedURL}`) } const jobid = `refresh-feed_${stringToHash(feedURL)}_${stringToHash( userList @@ -90,7 +95,7 @@ const updateSubscriptionGroup = async ( refreshContext, subscriptionIds: group.subscriptionIds, feedUrl: group.url, - lastFetchedTimestamps: group.fetchedDates.map( + mostRecentItemDates: group.mostRecentItemDates.map( (timestamp) => timestamp?.getTime() || 0 ), // unix timestamp in milliseconds lastFetchedChecksums: group.checksums, diff --git a/packages/api/src/jobs/rss/refreshFeed.ts b/packages/api/src/jobs/rss/refreshFeed.ts index f9339d6cc..d111f248d 100644 --- a/packages/api/src/jobs/rss/refreshFeed.ts +++ b/packages/api/src/jobs/rss/refreshFeed.ts @@ -1,21 +1,24 @@ import axios from 'axios' import crypto from 'crypto' -import * as jwt from 'jsonwebtoken' import { parseHTML } from 'linkedom' import Parser, { Item } from 'rss-parser' -import { promisify } from 'util' import { env } from '../../env' import { redisDataSource } from '../../redis_data_source' +import { validateUrl } from '../../services/create_page_save_request' +import { + updateSubscription, + updateSubscriptions, +} from '../../services/update_subscription' import createHttpTaskWithToken from '../../utils/createTask' +import { logger } from '../../utils/logger' import { RSSRefreshContext } from './refreshAllFeeds' -import { updateSubscription } from '../../services/update_subscription' type FolderType = 'following' | 'inbox' interface RefreshFeedRequest { subscriptionIds: string[] feedUrl: string - lastFetchedTimestamps: number[] // unix timestamp in milliseconds + mostRecentItemDates: number[] // unix timestamp in milliseconds scheduledTimestamps: number[] // unix timestamp in milliseconds lastFetchedChecksums: string[] userIds: string[] @@ -28,7 +31,7 @@ export const isRefreshFeedRequest = (data: any): data is RefreshFeedRequest => { return ( 'subscriptionIds' in data && 'feedUrl' in data && - 'lastFetchedTimestamps' in data && + 'mostRecentItemDates' in data && 'scheduledTimestamps' in data && 'userIds' in data && 'lastFetchedChecksums' in data && @@ -71,11 +74,14 @@ interface FetchContentTask { item: RssFeedItem } -export const isOldItem = (item: RssFeedItem, lastFetchedAt: number) => { +export const isOldItem = ( + item: RssFeedItem, + mostRecentItemTimestamp: number +) => { // existing items and items that were published before 24h const publishedAt = item.isoDate ? new Date(item.isoDate) : new Date() return ( - publishedAt <= new Date(lastFetchedAt) || + publishedAt <= new Date(mostRecentItemTimestamp) || publishedAt < new Date(Date.now() - 24 * 60 * 60 * 1000) ) } @@ -91,11 +97,11 @@ const isFeedBlocked = async (feedUrl: string) => { // if the feed has failed to fetch more than certain times, block it const maxFailures = parseInt(process.env.MAX_FEED_FETCH_FAILURES ?? '10') if (result && parseInt(result) > maxFailures) { - console.log('feed is blocked: ', feedUrl) + logger.info(`feed is blocked: ${feedUrl}`) return true } } catch (error) { - console.error('Failed to check feed block status', feedUrl, error) + logger.error('Failed to check feed block status', { feedUrl, error }) } return false @@ -111,7 +117,7 @@ const incrementFeedFailure = async (feedUrl: string) => { return result } catch (error) { - console.error('Failed to block feed', feedUrl, error) + logger.error('Failed to block feed', { feedUrl, error }) return null } } @@ -123,6 +129,9 @@ export const isContentFetchBlocked = (feedUrl: string) => { if (feedUrl.startsWith('https://lwn.net/headlines/newrss')) { return true } + if (feedUrl.startsWith('https://medium.com')) { + return true + } return false } @@ -156,7 +165,7 @@ export const fetchAndChecksum = async (url: string) => { return { url, content: dataStr, checksum: hash.digest('hex') } } catch (error) { - console.log(`Failed to fetch or hash content from ${url}.`, error) + logger.info(`Failed to fetch or hash content from ${url}.`, error) return null } } @@ -200,7 +209,7 @@ const parseFeed = async (url: string, content: string) => { // otherwise the error will be caught by the outer try catch return await parser.parseString(content) } catch (error) { - console.log(error) + logger.info(error) return null } } @@ -211,7 +220,7 @@ const isItemRecentlySaved = async (userId: string, url: string) => { const result = await redisDataSource.redisClient?.get(key) return !!result } catch (err) { - console.error('error checking if item is old', err) + logger.error('error checking if item is old', err) } // If we failed to check, assume the item is good return false @@ -247,7 +256,7 @@ const createTask = async ( ) => { const isRecentlySaved = await isItemRecentlySaved(userId, item.link) if (isRecentlySaved) { - console.log('Item recently saved', item.link) + logger.info(`Item recently saved ${item.link}`) return true } @@ -255,7 +264,7 @@ const createTask = async ( return createItemWithPreviewContent(userId, feedUrl, item) } - console.log(`adding fetch content task ${userId} ${item.link.trim()}`) + logger.info(`adding fetch content task ${userId} ${item.link.trim()}`) return addFetchContentTask(fetchContentTasks, userId, folder, item) } @@ -283,7 +292,7 @@ const fetchContentAndCreateItem = async ( }) return !!task } catch (error) { - console.error('Error while creating task', error) + logger.error('Error while creating task', error) return false } } @@ -325,12 +334,11 @@ const createItemWithPreviewContent = async ( }) return !!task } catch (error) { - console.error('Error while creating task', error) + logger.error('Error while creating task', error) return false } } -const signToken = promisify(jwt.sign) const parser = new Parser({ customFields: { item: [ @@ -388,7 +396,10 @@ const getUpdatePeriodInHours = (feed: RssFeed) => { } // get link following the order of preference: via, alternate, self -const getLink = (links: RssFeedItemLink[]): string | undefined => { +const getLink = ( + links: RssFeedItemLink[], + feedUrl: string +): string | undefined => { // sort links by preference const sortedLinks: string[] = [] @@ -410,7 +421,18 @@ const getLink = (links: RssFeedItemLink[]): string | undefined => { }) // return the first link that is not undefined - return sortedLinks.find((link) => !!link) + const itemUrl = sortedLinks.find((link) => !!link) + if (!itemUrl) { + return undefined + } + + // convert relative url to absolute url + const url = new URL(itemUrl, feedUrl).href + if (!validateUrl(url)) { + return undefined + } + + return url } const processSubscription = async ( @@ -419,107 +441,120 @@ const processSubscription = async ( userId: string, feedUrl: string, fetchResult: { content: string; checksum: string }, - lastFetchedAt: number, + mostRecentItemDate: number, scheduledAt: number, lastFetchedChecksum: string, fetchContent: boolean, folder: FolderType, feed: RssFeed ) => { + const refreshedAt = new Date() + let lastItemFetchedAt: Date | null = null let lastValidItem: RssFeedItem | null = null if (fetchResult.checksum === lastFetchedChecksum) { - console.log('feed has not been updated', feedUrl, lastFetchedChecksum) + logger.info('feed has not been updated', { feedUrl, lastFetchedChecksum }) return } const updatedLastFetchedChecksum = fetchResult.checksum // fetch feed - let itemCount = 0 + let itemCount = 0, + failedAt: Date | undefined const feedLastBuildDate = feed.lastBuildDate - console.log('Feed last build date', feedLastBuildDate) + logger.info(`Feed last build date ${feedLastBuildDate || 'N/A'}`) if ( feedLastBuildDate && - new Date(feedLastBuildDate) <= new Date(lastFetchedAt) + new Date(feedLastBuildDate) <= new Date(mostRecentItemDate) ) { - console.log('Skipping old feed', feedLastBuildDate) + logger.info(`Skipping old feed ${feedLastBuildDate}`) return } // save each item in the feed for (const item of feed.items) { - // use published or updated if isoDate is not available for atom feeds - const isoDate = - item.isoDate || item.published || item.updated || item.created - console.log('Processing feed item', item.links, item.isoDate, feedUrl) + try { + const guid = item.guid || item.link + // use published or updated if isoDate is not available for atom feeds + const isoDate = + item.isoDate || item.published || item.updated || item.created - if (!item.links || item.links.length === 0) { - console.log('Invalid feed item', item) - continue + logger.info('Processing feed item', { + guid, + links: item.links, + isoDate, + feedUrl, + }) + + if (!item.links || item.links.length === 0 || !guid) { + throw new Error('Invalid feed item') + } + + // fallback to guid if link is not available + const link = getLink(item.links, feedUrl) || guid + if (!link) { + throw new Error('Invalid feed item link') + } + + const feedItem = { + ...item, + isoDate, + link, + } + + const publishedAt = feedItem.isoDate + ? new Date(feedItem.isoDate) + : new Date() + // remember the last valid item + if ( + !lastValidItem || + (lastValidItem.isoDate && publishedAt > new Date(lastValidItem.isoDate)) + ) { + lastValidItem = feedItem + } + + // Max limit per-feed update + if (itemCount > 99) { + continue + } + + // skip old items + if (isOldItem(feedItem, mostRecentItemDate)) { + logger.info(`Skipping old feed item ${feedItem.link}`) + continue + } + + const created = await createTask( + fetchContentTasks, + userId, + feedUrl, + feedItem, + fetchContent, + folder + ) + if (!created) { + throw new Error('Failed to create task for feed item') + } + + // remember the last item fetched at + if (!lastItemFetchedAt || publishedAt > lastItemFetchedAt) { + lastItemFetchedAt = publishedAt + } + + itemCount = itemCount + 1 + } catch (error) { + logger.error('Error while saving RSS feed item', { error, item }) + failedAt = new Date() } - - const link = getLink(item.links) - if (!link) { - console.log('Invalid feed item links', item.links) - continue - } - - const feedItem = { - ...item, - isoDate, - link, - } - - const publishedAt = feedItem.isoDate - ? new Date(feedItem.isoDate) - : new Date() - // remember the last valid item - if ( - !lastValidItem || - (lastValidItem.isoDate && publishedAt > new Date(lastValidItem.isoDate)) - ) { - lastValidItem = feedItem - } - - // Max limit per-feed update - if (itemCount > 99) { - continue - } - - // skip old items - if (isOldItem(feedItem, lastFetchedAt)) { - console.log('Skipping old feed item', feedItem.link) - continue - } - - const created = await createTask( - fetchContentTasks, - userId, - feedUrl, - feedItem, - fetchContent, - folder - ) - if (!created) { - console.error('Failed to create task for feed item', feedItem.link) - continue - } - - // remember the last item fetched at - if (!lastItemFetchedAt || publishedAt > lastItemFetchedAt) { - lastItemFetchedAt = publishedAt - } - - itemCount = itemCount + 1 } // no items saved - if (!lastItemFetchedAt) { + if (!lastItemFetchedAt && !failedAt) { // the feed has been fetched before, no new valid items found - if (lastFetchedAt || !lastValidItem) { - console.log('No new valid items found') + if (mostRecentItemDate || !lastValidItem) { + logger.info('No new valid items found') return } @@ -533,95 +568,109 @@ const processSubscription = async ( folder ) if (!created) { - console.error('Failed to create task for feed item', lastValidItem.link) - throw new Error('Failed to create task for feed item') + logger.error('Failed to create task for feed item', { + url: lastValidItem.link, + }) + failedAt = new Date() } lastItemFetchedAt = lastValidItem.isoDate ? new Date(lastValidItem.isoDate) - : new Date() + : refreshedAt } const updateFrequency = getUpdateFrequency(feed) const updatePeriodInMs = getUpdatePeriodInHours(feed) * 60 * 60 * 1000 const nextScheduledAt = scheduledAt + updatePeriodInMs * updateFrequency - // update subscription lastFetchedAt + // update subscription mostRecentItemDate and refreshedAt const updatedSubscription = await updateSubscription(userId, subscriptionId, { - lastFetchedAt: lastItemFetchedAt, + mostRecentItemDate: lastItemFetchedAt, lastFetchedChecksum: updatedLastFetchedChecksum, scheduledAt: new Date(nextScheduledAt), + refreshedAt, + failedAt, }) - console.log('Updated subscription', updatedSubscription) + logger.info('Updated subscription', updatedSubscription) } export const refreshFeed = async (request: any) => { if (isRefreshFeedRequest(request)) { return _refreshFeed(request) } - console.log('not a feed to refresh') + logger.info('not a feed to refresh') return false } export const _refreshFeed = async (request: RefreshFeedRequest) => { - try { - const { - feedUrl, - subscriptionIds, - lastFetchedTimestamps, - scheduledTimestamps, - userIds, - lastFetchedChecksums, - fetchContents, - folders, - refreshContext, - } = request - console.log('Processing feed', feedUrl, { refreshContext: refreshContext }) + const { + feedUrl, + subscriptionIds, + mostRecentItemDates, + scheduledTimestamps, + userIds, + lastFetchedChecksums, + fetchContents, + folders, + refreshContext, + } = request + logger.info('Processing feed', feedUrl, { refreshContext: refreshContext }) + + try { const isBlocked = await isFeedBlocked(feedUrl) if (isBlocked) { - console.log('feed is blocked: ', feedUrl) - return + logger.info(`feed is blocked: ${feedUrl}`) + throw new Error('feed is blocked') } const fetchResult = await fetchAndChecksum(feedUrl) if (!fetchResult) { - console.error('Failed to fetch RSS feed', feedUrl) + logger.error(`Failed to fetch RSS feed ${feedUrl}`) await incrementFeedFailure(feedUrl) - return + throw new Error('Failed to fetch RSS feed') } const feed = await parseFeed(feedUrl, fetchResult.content) if (!feed) { - console.error('Failed to parse RSS feed', feedUrl) + logger.error(`Failed to parse RSS feed ${feedUrl}`) await incrementFeedFailure(feedUrl) - return + throw new Error('Failed to parse RSS feed') } let allowFetchContent = true if (isContentFetchBlocked(feedUrl)) { - console.log('fetching content blocked for feed: ', feedUrl) + logger.info(`fetching content blocked for feed: ${feedUrl}`) allowFetchContent = false } - console.log('Fetched feed', feed.title, new Date()) + logger.info('Fetched feed', { title: feed.title, at: new Date() }) const fetchContentTasks = new Map() // url -> FetchContentTask // process each subscription sequentially for (let i = 0; i < subscriptionIds.length; i++) { - await processSubscription( - fetchContentTasks, - subscriptionIds[i], - userIds[i], - feedUrl, - fetchResult, - lastFetchedTimestamps[i], - scheduledTimestamps[i], - lastFetchedChecksums[i], - fetchContents[i] && allowFetchContent, - folders[i], - feed - ) + const subscriptionId = subscriptionIds[i] + + try { + await processSubscription( + fetchContentTasks, + subscriptionId, + userIds[i], + feedUrl, + fetchResult, + mostRecentItemDates[i], + scheduledTimestamps[i], + lastFetchedChecksums[i], + fetchContents[i] && allowFetchContent, + folders[i], + feed + ) + } catch (error) { + logger.error('Error while processing subscription', { + error, + subscriptionId, + }) + } } // create fetch content tasks @@ -632,7 +681,22 @@ export const _refreshFeed = async (request: RefreshFeedRequest) => { task.item ) } - } catch (e) { - console.error('Error while saving RSS feeds', e) + + return true + } catch (error) { + logger.error('Error while saving RSS feeds', { + feedUrl, + subscriptionIds, + error, + }) + + const now = new Date() + // mark subscriptions as error if we failed to get the feed + await updateSubscriptions(subscriptionIds, { + refreshedAt: now, + failedAt: now, + }) + + return false } } diff --git a/packages/api/src/jobs/save_page.ts b/packages/api/src/jobs/save_page.ts index 9eccf5efb..1f2d276e4 100644 --- a/packages/api/src/jobs/save_page.ts +++ b/packages/api/src/jobs/save_page.ts @@ -1,4 +1,3 @@ -import { Readability } from '@omnivore/readability' import axios from 'axios' import jwt from 'jsonwebtoken' import { promisify } from 'util' @@ -9,14 +8,15 @@ import { } from '../generated/graphql' import { redisDataSource } from '../redis_data_source' import { userRepository } from '../repository/user' +import { saveFile } from '../services/save_file' import { savePage } from '../services/save_page' +import { uploadFile } from '../services/upload_file' import { logger } from '../utils/logger' const signToken = promisify(jwt.sign) const IMPORTER_METRICS_COLLECTOR_URL = env.queue.importerMetricsUrl const JWT_SECRET = env.server.jwtSecret -const REST_BACKEND_ENDPOINT = `${env.server.internalApiUrl}/api` const MAX_ATTEMPTS = 2 const REQUEST_TIMEOUT = 30000 // 30 seconds @@ -35,54 +35,15 @@ interface Data { taskId?: string } -interface UploadFileResponse { - data: { - uploadFileRequest: { - id: string - uploadSignedUrl: string - uploadFileId: string - createdPageId: string - errorCodes?: string[] - } - } -} - -interface CreateArticleResponse { - data: { - createArticle: { - createdArticle: { - id: string - } - errorCodes: string[] - } - } -} - -interface SavePageResponse { - data: { - savePage: { - url: string - clientRequestId: string - errorCodes?: string[] - } - } -} - interface FetchResult { finalUrl: string title?: string content?: string contentType?: string - readabilityResult?: Readability.ParseResult } const isFetchResult = (obj: unknown): obj is FetchResult => { - return ( - typeof obj === 'object' && - obj !== null && - 'finalUrl' in obj && - 'title' in obj - ) + return typeof obj === 'object' && obj !== null && 'finalUrl' in obj } const uploadToSignedUrl = async ( @@ -90,12 +51,18 @@ const uploadToSignedUrl = async ( contentType: string, contentObjUrl: string ) => { + logger.info('uploading to signed url', { + uploadSignedUrl, + contentType, + contentObjUrl, + }) + try { const stream = await axios.get(contentObjUrl, { responseType: 'stream', timeout: REQUEST_TIMEOUT, }) - return axios.put(uploadSignedUrl, stream.data, { + return await axios.put(uploadSignedUrl, stream.data, { headers: { 'Content-Type': contentType, }, @@ -104,65 +71,7 @@ const uploadToSignedUrl = async ( timeout: REQUEST_TIMEOUT, }) } catch (error) { - console.error('error uploading to signed url', error) - return null - } -} - -const getUploadIdAndSignedUrl = async ( - userId: string, - url: string, - articleSavingRequestId: string -) => { - const auth = await signToken({ uid: userId }, JWT_SECRET) - const data = JSON.stringify({ - query: `mutation UploadFileRequest($input: UploadFileRequestInput!) { - uploadFileRequest(input:$input) { - ... on UploadFileRequestError { - errorCodes - } - ... on UploadFileRequestSuccess { - id - uploadSignedUrl - } - } - }`, - variables: { - input: { - url, - contentType: 'application/pdf', - clientRequestId: articleSavingRequestId, - }, - }, - }) - - try { - const response = await axios.post( - `${REST_BACKEND_ENDPOINT}/graphql`, - data, - { - headers: { - Cookie: `auth=${auth as string};`, - 'Content-Type': 'application/json', - }, - timeout: REQUEST_TIMEOUT, - } - ) - - if ( - response.data.data.uploadFileRequest.errorCodes && - response.data.data.uploadFileRequest.errorCodes?.length > 0 - ) { - console.error( - 'Error while getting upload id and signed url', - response.data.data.uploadFileRequest.errorCodes[0] - ) - return null - } - - return response.data.data.uploadFileRequest - } catch (e) { - console.error('error getting upload id and signed url', e) + logger.error('error uploading to signed url', error) return null } } @@ -172,73 +81,31 @@ const uploadPdf = async ( userId: string, articleSavingRequestId: string ) => { - const uploadResult = await getUploadIdAndSignedUrl( - userId, - url, - articleSavingRequestId + const result = await uploadFile( + { + url, + contentType: 'application/pdf', + clientRequestId: articleSavingRequestId, + createPageEntry: true, + }, + userId ) - if (!uploadResult) { + if (!result.uploadSignedUrl || !result.createdPageId) { throw new Error('error while getting upload id and signed url') } + const uploaded = await uploadToSignedUrl( - uploadResult.uploadSignedUrl, + result.uploadSignedUrl, 'application/pdf', url ) if (!uploaded) { throw new Error('error while uploading pdf') } - return uploadResult.id -} -const sendCreateArticleMutation = async (userId: string, input: unknown) => { - const data = JSON.stringify({ - query: `mutation CreateArticle ($input: CreateArticleInput!){ - createArticle(input:$input){ - ... on CreateArticleSuccess{ - createdArticle{ - id - } - } - ... on CreateArticleError{ - errorCodes - } - } - }`, - variables: { - input, - }, - }) - - const auth = await signToken({ uid: userId }, JWT_SECRET) - try { - const response = await axios.post( - `${REST_BACKEND_ENDPOINT}/graphql`, - data, - { - headers: { - Cookie: `auth=${auth as string};`, - 'Content-Type': 'application/json', - }, - timeout: REQUEST_TIMEOUT, - } - ) - - if ( - response.data.data.createArticle.errorCodes && - response.data.data.createArticle.errorCodes.length > 0 - ) { - console.error( - 'error while creating article', - response.data.data.createArticle.errorCodes[0] - ) - return null - } - - return response.data.data.createArticle - } catch (error) { - console.error('error creating article', error) - return null + return { + uploadFileId: result.id, + itemId: result.createdPageId, } } @@ -248,6 +115,7 @@ const sendImportStatusUpdate = async ( isImported?: boolean ) => { try { + logger.info('sending import status update') const auth = await signToken({ uid: userId }, JWT_SECRET) await axios.post( @@ -265,7 +133,7 @@ const sendImportStatusUpdate = async ( } ) } catch (e) { - console.error('error while sending import status update', e) + logger.error('error while sending import status update', e) } } @@ -285,7 +153,7 @@ const getCachedFetchResult = async (url: string) => { throw new Error('fetch result is not valid') } - console.log('fetch result is cached', url) + logger.info('fetch result is cached', url) return fetchResult } @@ -294,7 +162,6 @@ export const savePageJob = async (data: Data, attemptsMade: number) => { const { userId, articleSavingRequestId, - state, labels, source, folder, @@ -304,38 +171,49 @@ export const savePageJob = async (data: Data, attemptsMade: number) => { taskId, url, } = data - let isImported, isSaved + let isImported, + isSaved, + state = data.state try { - console.log(`savePageJob: ${userId} ${url}`) + logger.info(`savePageJob: ${userId} ${url}`) // get the fetch result from cache - const { title, content, contentType, readabilityResult } = - await getCachedFetchResult(url) + const fetchedResult = await getCachedFetchResult(url) + const { title, contentType } = fetchedResult + let content = fetchedResult.content + + const user = await userRepository.findById(userId) + if (!user) { + logger.error('Unable to save job, user can not be found.', { + userId, + url, + }) + // if the user is not found, we do not retry + return false + } // for pdf content, we need to upload the pdf if (contentType === 'application/pdf') { - const encodedUrl = encodeURI(url) + const uploadResult = await uploadPdf(url, userId, articleSavingRequestId) - const uploadFileId = await uploadPdf( - encodedUrl, - userId, - articleSavingRequestId + const result = await saveFile( + { + url, + uploadFileId: uploadResult.uploadFileId, + state: state ? (state as ArticleSavingRequestStatus) : undefined, + labels, + source, + folder, + subscription: rssFeedUrl, + savedAt, + publishedAt, + clientRequestId: uploadResult.itemId, + }, + user ) - const uploadedPdf = await sendCreateArticleMutation(userId, { - url: encodedUrl, - articleSavingRequestId, - uploadFileId, - state, - labels, - source, - folder, - rssFeedUrl, - savedAt, - publishedAt, - }) - if (!uploadedPdf) { - throw new Error('error while saving uploaded pdf') + if (result.__typename == 'SaveError') { + throw new Error(result.message || result.errorCodes[0]) } isSaved = true @@ -344,18 +222,10 @@ export const savePageJob = async (data: Data, attemptsMade: number) => { } if (!content) { - throw new Error( - 'Invalid SavePage job, fetch result missing required data' - ) - } - - const user = await userRepository.findById(userId) - if (!user) { - logger.error('Unable to save job, user can not be found.', { - userId, - url, - }) - throw new Error('Unable to save job, user can not be found.') + logger.info('content is not fetched', url) + // set the state to failed if we don't have content + content = 'Failed to fetch content' + state = ArticleSavingRequestStatus.Failed } // for non-pdf content, we need to save the page @@ -365,7 +235,6 @@ export const savePageJob = async (data: Data, attemptsMade: number) => { clientRequestId: articleSavingRequestId, title, originalContent: content, - parseResult: readabilityResult, state: state ? (state as ArticleSavingRequestStatus) : undefined, labels: labels, rssFeedUrl, @@ -377,26 +246,24 @@ export const savePageJob = async (data: Data, attemptsMade: number) => { user ) - // if (result.__typename == 'SaveError') { - // logger.error('Error saving page', { userId, url, result }) - // throw new Error('Error saving page') - // } + if (result.__typename == 'SaveError') { + throw new Error(result.message || result.errorCodes[0]) + } - // if the readability result is not parsed, the import is failed - isImported = !!readabilityResult + isImported = true isSaved = true } catch (e) { if (e instanceof Error) { - console.error('error while saving page', e.message) + logger.error(`error while saving page: ${e.message}`) } else { - console.error('error while saving page', 'unknown error') + logger.error('error while saving page: unknown error') } throw e } finally { const lastAttempt = attemptsMade === MAX_ATTEMPTS - 1 if (lastAttempt) { - console.log('last attempt reached', data.url) + logger.info(`last attempt reached ${data.url}`) } if (taskId && (isSaved || lastAttempt)) { diff --git a/packages/api/src/jobs/trigger_rule.ts b/packages/api/src/jobs/trigger_rule.ts new file mode 100644 index 000000000..72d902a90 --- /dev/null +++ b/packages/api/src/jobs/trigger_rule.ts @@ -0,0 +1,144 @@ +import { LibraryItem, LibraryItemState } from '../entity/library_item' +import { Rule, RuleAction, RuleActionType, RuleEventType } from '../entity/rule' +import { addLabelsToLibraryItem } from '../services/labels' +import { + SearchArgs, + searchLibraryItems, + updateLibraryItem, +} from '../services/library_item' +import { findEnabledRules } from '../services/rules' +import { sendPushNotifications } from '../services/user' +import { logger } from '../utils/logger' + +export interface TriggerRuleJobData { + libraryItemId: string + userId: string + ruleEventType: RuleEventType +} + +interface RuleActionObj { + userId: string + action: RuleAction + libraryItem: LibraryItem +} + +export const TRIGGER_RULE_JOB_NAME = 'trigger-rule' + +type RuleActionFunc = (obj: RuleActionObj) => Promise + +const addLabels = async (obj: RuleActionObj) => { + const labelIds = obj.action.params + + return addLabelsToLibraryItem( + labelIds, + obj.libraryItem.id, + obj.userId, + 'system' + ) +} + +const archivePage = async (obj: RuleActionObj) => { + return updateLibraryItem( + obj.libraryItem.id, + { archivedAt: new Date(), state: LibraryItemState.Archived }, + obj.userId, + undefined, + true + ) +} + +const markPageAsRead = async (obj: RuleActionObj) => { + return updateLibraryItem( + obj.libraryItem.id, + { + readingProgressTopPercent: 100, + readingProgressBottomPercent: 100, + readAt: new Date(), + }, + obj.userId, + undefined, + true + ) +} + +const sendNotification = async (obj: RuleActionObj) => { + const item = obj.libraryItem + const message = { + title: item.author || item.siteName || 'Omnivore', + body: item.title, + } + + return sendPushNotifications(obj.userId, message, 'rule') +} + +const getRuleAction = (actionType: RuleActionType): RuleActionFunc => { + switch (actionType) { + case RuleActionType.AddLabel: + return addLabels + case RuleActionType.Archive: + return archivePage + case RuleActionType.MarkAsRead: + return markPageAsRead + case RuleActionType.SendNotification: + return sendNotification + } +} + +const triggerActions = async ( + userId: string, + rules: Rule[], + data: TriggerRuleJobData +) => { + const actionPromises: Promise[] = [] + + for (const rule of rules) { + const itemId = data.libraryItemId + const searchArgs: SearchArgs = { + includeContent: false, + includeDeleted: false, + includePending: false, + size: 1, + query: `(${rule.filter}) AND includes:${itemId}`, + } + + const libraryItems = await searchLibraryItems(searchArgs, userId) + if (libraryItems.count === 0) { + logger.info(`No pages found for rule ${rule.id}`) + continue + } + + const libraryItem = libraryItems.libraryItems[0] + + for (const action of rule.actions) { + const actionFunc = getRuleAction(action.type) + const actionObj: RuleActionObj = { + userId, + action, + libraryItem, + } + + actionPromises.push(actionFunc(actionObj)) + } + } + + try { + await Promise.all(actionPromises) + } catch (error) { + logger.error(error) + } +} + +export const triggerRule = async (data: TriggerRuleJobData) => { + const { userId, ruleEventType } = data + + // get rules by calling api + const rules = await findEnabledRules(userId, ruleEventType) + if (rules.length === 0) { + console.log('No rules found') + return false + } + + await triggerActions(userId, rules, data) + + return true +} diff --git a/packages/api/src/jobs/update_pdf_content.ts b/packages/api/src/jobs/update_pdf_content.ts index 60850fd0a..ff346a534 100644 --- a/packages/api/src/jobs/update_pdf_content.ts +++ b/packages/api/src/jobs/update_pdf_content.ts @@ -1,5 +1,4 @@ import { - UpdateContentMessage, isUpdateContentMessage, updateContentForFileItem, } from '../services/update_pdf_content' @@ -9,6 +8,6 @@ export const updatePDFContentJob = async (data: unknown): Promise => { if (isUpdateContentMessage(data)) { return await updateContentForFileItem(data) } - logger.log('update_pdf_content data is not a update message', { data }) + logger.info('update_pdf_content data is not a update message', { data }) return false } diff --git a/packages/api/src/pubsub.ts b/packages/api/src/pubsub.ts index ea1bcf987..02c35f3d4 100644 --- a/packages/api/src/pubsub.ts +++ b/packages/api/src/pubsub.ts @@ -1,7 +1,9 @@ import { PubSub } from '@google-cloud/pubsub' import express from 'express' +import { RuleEventType } from './entity/rule' import { env } from './env' import { ReportType } from './generated/graphql' +import { enqueueTriggerRuleJob } from './utils/createTask' import { deepDelete } from './utils/helpers' import { buildLogger } from './utils/logger' @@ -41,11 +43,21 @@ export const createPubSubClient = (): PubsubClient => { Buffer.from(JSON.stringify({ userId, email, name, username })) ) }, - entityCreated: ( + entityCreated: async ( type: EntityType, data: T, userId: string ): Promise => { + // queue trigger rule job + if (type === EntityType.PAGE) { + const libraryItemId = (data as T & { id: string }).id + await enqueueTriggerRuleJob({ + userId, + ruleEventType: RuleEventType.PageCreated, + libraryItemId, + }) + } + const cleanData = deepDelete( data as T & Record, [...fieldsToDelete] @@ -56,11 +68,21 @@ export const createPubSubClient = (): PubsubClient => { Buffer.from(JSON.stringify({ type, userId, ...cleanData })) ) }, - entityUpdated: ( + entityUpdated: async ( type: EntityType, data: T, userId: string ): Promise => { + // queue trigger rule job + if (type === EntityType.PAGE) { + const libraryItemId = (data as T & { id: string }).id + await enqueueTriggerRuleJob({ + userId, + ruleEventType: RuleEventType.PageUpdated, + libraryItemId, + }) + } + const cleanData = deepDelete( data as T & Record, [...fieldsToDelete] diff --git a/packages/api/src/queue-processor.ts b/packages/api/src/queue-processor.ts index 7ccd5e272..cd89e1c69 100644 --- a/packages/api/src/queue-processor.ts +++ b/packages/api/src/queue-processor.ts @@ -2,17 +2,19 @@ /* eslint-disable @typescript-eslint/restrict-template-expressions */ /* eslint-disable @typescript-eslint/require-await */ /* eslint-disable @typescript-eslint/no-misused-promises */ -import { Job, QueueEvents, Worker, Queue } from 'bullmq' +import { Job, Queue, QueueEvents, Worker, JobType } from 'bullmq' import express, { Express } from 'express' import { SnakeNamingStrategy } from 'typeorm-naming-strategies' import { appDataSource } from './data_source' import { env } from './env' +import { findThumbnail, THUMBNAIL_JOB } from './jobs/find_thumbnail' import { refreshAllFeeds } from './jobs/rss/refreshAllFeeds' import { refreshFeed } from './jobs/rss/refreshFeed' import { savePageJob } from './jobs/save_page' +import { updatePDFContentJob } from './jobs/update_pdf_content' import { redisDataSource } from './redis_data_source' import { CustomTypeOrmLogger } from './utils/logger' -import { updatePDFContentJob } from './jobs/update_pdf_content' +import { triggerRule, TRIGGER_RULE_JOB_NAME } from './jobs/trigger_rule' export const QUEUE_NAME = 'omnivore-backend-queue' @@ -39,8 +41,8 @@ const main = async () => { const port = process.env.PORT || 3002 redisDataSource.setOptions({ - REDIS_URL: env.redis.url, - REDIS_CERT: env.redis.cert, + cache: env.redis.cache, + mq: env.redis.mq, }) appDataSource.setOptions({ @@ -63,6 +65,26 @@ const main = async () => { // respond healthy to auto-scaler. app.get('/_ah/health', (req, res) => res.sendStatus(200)) + app.get('/metrics', async (_, res) => { + const queue = await getBackendQueue() + if (!queue) { + res.sendStatus(400) + return + } + + let output = '' + const metrics: JobType[] = ['active', 'failed', 'completed', 'prioritized'] + const counts = await queue.getJobCounts(...metrics) + console.log('counts: ', counts) + + metrics.forEach((metric, idx) => { + output += `# TYPE omnivore_queue_messages_${metric} gauge\n` + output += `omnivore_queue_messages_${metric}{queue="${QUEUE_NAME}"} ${counts[metric]}\n` + }) + + res.status(200).setHeader('Content-Type', 'text/plain').send(output) + }) + const server = app.listen(port, () => { console.log(`[queue-processor]: started`) }) @@ -78,17 +100,14 @@ const main = async () => { throw '[queue-processor] error redis is not initialized' } - const queue = new Queue(QUEUE_NAME, { - connection: workerRedisClient, - }) - const worker = new Worker( QUEUE_NAME, async (job: Job) => { switch (job.name) { case 'refresh-all-feeds': { - const counts = await queue.getJobCounts('wait') - if (counts.wait > 1000) { + const queue = await getBackendQueue() + const counts = await queue?.getJobCounts('prioritized') + if (counts && counts.wait > 1000) { return } return await refreshAllFeeds(appDataSource) @@ -102,8 +121,11 @@ const main = async () => { case 'update-pdf-content': { return updatePDFContentJob(job.data) } + case THUMBNAIL_JOB: + return findThumbnail(job.data) + case TRIGGER_RULE_JOB_NAME: + return triggerRule(job.data) } - return true }, { connection: workerRedisClient, diff --git a/packages/api/src/readability.d.ts b/packages/api/src/readability.d.ts index 4722588cd..fcfcc1e55 100644 --- a/packages/api/src/readability.d.ts +++ b/packages/api/src/readability.d.ts @@ -166,6 +166,7 @@ declare module '@omnivore/readability' { /** Article published date */ publishedDate?: Date | null language?: string | null + documentElement: HTMLElement } } diff --git a/packages/api/src/redis_data_source.ts b/packages/api/src/redis_data_source.ts index ef7cf55e3..051bcbcc0 100644 --- a/packages/api/src/redis_data_source.ts +++ b/packages/api/src/redis_data_source.ts @@ -1,9 +1,14 @@ import Redis, { RedisOptions } from 'ioredis' import { env } from './env' +import { logger } from './utils/logger' +type RedisClientType = 'cache' | 'mq' +type RedisDataSourceOption = { + url?: string + cert?: string +} export type RedisDataSourceOptions = { - REDIS_URL?: string - REDIS_CERT?: string + [key in RedisClientType]: RedisDataSourceOption } export class RedisDataSource { @@ -22,8 +27,9 @@ export class RedisDataSource { async initialize(): Promise { if (this.isInitialized) throw 'Error already initialized' - this.redisClient = createIORedisClient('app', this.options) - this.workerRedisClient = createIORedisClient('worker', this.options) + this.redisClient = createIORedisClient('cache', this.options) + this.workerRedisClient = + createIORedisClient('mq', this.options) || this.redisClient // if mq is not defined, use cache this.isInitialized = true return Promise.resolve(this) @@ -39,23 +45,27 @@ export class RedisDataSource { await this.workerRedisClient?.quit() await this.redisClient?.quit() } catch (err) { - console.error('error while shutting down redis', err) + logger.error('error while shutting down redis', err) } } } const createIORedisClient = ( - name: string, + name: RedisClientType, options: RedisDataSourceOptions ): Redis | undefined => { - const redisURL = options.REDIS_URL + const option = options[name] + const redisURL = option.url if (!redisURL) { - throw 'Error: no redisURL supplied' + logger.info(`no redisURL supplied: ${name}`) + return undefined } + + const redisCert = option.cert const tls = - redisURL.startsWith('rediss://') && options.REDIS_CERT + redisURL.startsWith('rediss://') && redisCert ? { - ca: options.REDIS_CERT, + ca: redisCert, rejectUnauthorized: false, } : undefined @@ -92,7 +102,6 @@ const createIORedisClient = ( return new Redis(redisURL, redisOptions) } -export const redisDataSource = new RedisDataSource({ - REDIS_URL: env.redis.url, - REDIS_CERT: env.redis.cert, -}) +export const redisDataSource = new RedisDataSource( + env.redis as RedisDataSourceOptions +) diff --git a/packages/api/src/resolvers/article/index.ts b/packages/api/src/resolvers/article/index.ts index 03cce990e..93710f98f 100644 --- a/packages/api/src/resolvers/article/index.ts +++ b/packages/api/src/resolvers/article/index.ts @@ -87,11 +87,13 @@ import { import { parsedContentToLibraryItem } from '../../services/save_page' import { findUploadFileById, + itemTypeForContentType, setFileUploadComplete, } from '../../services/upload_file' import { traceAs } from '../../tracing' import { analytics } from '../../utils/analytics' import { isSiteBlockedForParse } from '../../utils/blocked' +import { authorized } from '../../utils/gql-utils' import { cleanUrl, errorHandler, @@ -102,7 +104,6 @@ import { titleForFilePath, userDataToUser, } from '../../utils/helpers' -import { authorized } from '../../utils/gql-utils' import { contentConverter, getDistillerResult, @@ -111,7 +112,6 @@ import { parsePreparedContent, } from '../../utils/parser' import { getStorageFileDetails } from '../../utils/uploads' -import { itemTypeForContentType } from '../upload_files' export enum ArticleFormat { Markdown = 'markdown', @@ -908,7 +908,12 @@ export const setFavoriteArticleResolver = authorized< const labels = await findOrCreateLabels([label], uid) // adds Favorites label to item - await addLabelsToLibraryItem(labels, id, uid) + await addLabelsToLibraryItem( + labels.map((l) => l.id), + id, + uid, + 'user' + ) return { success: true, diff --git a/packages/api/src/resolvers/function_resolvers.ts b/packages/api/src/resolvers/function_resolvers.ts index 6cff177ca..ad3e3ac96 100644 --- a/packages/api/src/resolvers/function_resolvers.ts +++ b/packages/api/src/resolvers/function_resolvers.ts @@ -477,6 +477,10 @@ export const functionResolvers = { DEFAULT_SUBSCRIPTION_FOLDER ) }, + // for campability with old clients + lastFetchedAt(subscription: Subscription) { + return subscription.refreshedAt + }, }, NewsletterEmail: { subscriptionCount(newsletterEmail: NewsletterEmail) { diff --git a/packages/api/src/resolvers/subscriptions/index.ts b/packages/api/src/resolvers/subscriptions/index.ts index b7e1507e4..a13529325 100644 --- a/packages/api/src/resolvers/subscriptions/index.ts +++ b/packages/api/src/resolvers/subscriptions/index.ts @@ -4,6 +4,8 @@ import { Brackets, In } from 'typeorm' import { DEFAULT_SUBSCRIPTION_FOLDER, Subscription, + SubscriptionStatus, + SubscriptionType, } from '../../entity/subscription' import { env } from '../../env' import { @@ -28,8 +30,6 @@ import { SubscriptionsError, SubscriptionsErrorCode, SubscriptionsSuccess, - SubscriptionStatus, - SubscriptionType, UnsubscribeError, UnsubscribeErrorCode, UnsubscribeSuccess, @@ -41,13 +41,13 @@ import { getRepository } from '../../repository' import { feedRepository } from '../../repository/feed' import { validateUrl } from '../../services/create_page_save_request' import { unsubscribe } from '../../services/subscriptions' +import { updateSubscription } from '../../services/update_subscription' import { Merge } from '../../util' import { analytics } from '../../utils/analytics' import { enqueueRssFeedFetch } from '../../utils/createTask' -import { getAbsoluteUrl, keysToCamelCase } from '../../utils/helpers' import { authorized } from '../../utils/gql-utils' +import { getAbsoluteUrl, keysToCamelCase } from '../../utils/helpers' import { parseFeed, parseOpml, RSS_PARSER_CONFIG } from '../../utils/parser' -import { updateSubscription } from '../../services/update_subscription' type PartialSubscription = Omit @@ -61,8 +61,7 @@ export const subscriptionsResolver = authorized< QuerySubscriptionsArgs >(async (_obj, { sort, type }, { uid, log }) => { try { - const sortBy = - sort?.by === SortBy.UpdatedTime ? 'lastFetchedAt' : 'createdAt' + const sortBy = sort?.by === SortBy.UpdatedTime ? 'refreshedAt' : 'createdAt' const sortOrder = sort?.order === SortOrder.Ascending ? 'ASC' : 'DESC' const queryBuilder = getRepository(Subscription) @@ -239,7 +238,7 @@ export const subscribeResolver = authorized< url: feedUrl, subscriptionIds: [updatedSubscription.id], scheduledDates: [new Date()], // fetch immediately - fetchedDates: [updatedSubscription.lastFetchedAt || null], + mostRecentItemDates: [updatedSubscription.mostRecentItemDate || null], checksums: [updatedSubscription.lastFetchedChecksum || null], fetchContents: [updatedSubscription.fetchContent], folders: [updatedSubscription.folder || DEFAULT_SUBSCRIPTION_FOLDER], @@ -289,7 +288,7 @@ export const subscribeResolver = authorized< url: feedUrl, subscriptionIds: [newSubscription.id], scheduledDates: [new Date()], // fetch immediately - fetchedDates: [null], + mostRecentItemDates: [null], checksums: [null], fetchContents: [newSubscription.fetchContent], folders: [newSubscription.folder || DEFAULT_SUBSCRIPTION_FOLDER], @@ -319,7 +318,7 @@ export const updateSubscriptionResolver = authorized< UpdateSubscriptionSuccessPartial, UpdateSubscriptionError, MutationUpdateSubscriptionArgs ->(async (_, { input }, { authTrx, uid, log }) => { +>(async (_, { input }, { uid, log }) => { try { analytics.track({ userId: uid, diff --git a/packages/api/src/resolvers/upload_files/index.ts b/packages/api/src/resolvers/upload_files/index.ts index b22395458..74caee344 100644 --- a/packages/api/src/resolvers/upload_files/index.ts +++ b/packages/api/src/resolvers/upload_files/index.ts @@ -1,55 +1,17 @@ -/* eslint-disable @typescript-eslint/no-unused-vars */ -import normalizeUrl from 'normalize-url' -import path from 'path' -import { LibraryItemState } from '../../entity/library_item' -import { UploadFile } from '../../entity/upload_file' import { env } from '../../env' import { MutationUploadFileRequestArgs, - PageType, UploadFileRequestError, - UploadFileRequestErrorCode, UploadFileRequestSuccess, - UploadFileStatus, } from '../../generated/graphql' -import { validateUrl } from '../../services/create_page_save_request' -import { - createLibraryItem, - findLibraryItemByUrl, - updateLibraryItem, -} from '../../services/library_item' +import { uploadFile } from '../../services/upload_file' import { analytics } from '../../utils/analytics' -import { generateSlug } from '../../utils/helpers' import { authorized } from '../../utils/gql-utils' - -import { - contentReaderForLibraryItem, - generateUploadFilePathName, - generateUploadSignedUrl, -} from '../../utils/uploads' - -const isFileUrl = (url: string): boolean => { - const parsedUrl = new URL(url) - return parsedUrl.protocol == 'file:' -} - -export const itemTypeForContentType = (contentType: string) => { - if (contentType == 'application/epub+zip') { - return PageType.Book - } - return PageType.File -} - export const uploadFileRequestResolver = authorized< UploadFileRequestSuccess, UploadFileRequestError, MutationUploadFileRequestArgs ->(async (_, { input }, ctx) => { - const { authTrx, uid, log } = ctx - let uploadFileData: { id: string | null } = { - id: null, - } - +>(async (_, { input }, { uid }) => { analytics.track({ userId: uid, event: 'file_upload_request', @@ -59,112 +21,5 @@ export const uploadFileRequestResolver = authorized< }, }) - let title: string - let fileName: string - try { - const url = normalizeUrl(new URL(input.url).href, { - stripHash: true, - stripWWW: false, - }) - title = decodeURI(path.basename(new URL(url).pathname, '.pdf')) - fileName = decodeURI(path.basename(new URL(url).pathname)).replace( - /[^a-zA-Z0-9-_.]/g, - '' - ) - - if (!fileName) { - fileName = 'content.pdf' - } - - if (!isFileUrl(url)) { - try { - validateUrl(url) - } catch (error) { - log.info('illegal file input url', error) - return { - errorCodes: [UploadFileRequestErrorCode.BadInput], - } - } - } - } catch { - return { errorCodes: [UploadFileRequestErrorCode.BadInput] } - } - - uploadFileData = await authTrx((t) => - t.getRepository(UploadFile).save({ - url: input.url, - user: { id: uid }, - fileName, - status: UploadFileStatus.Initialized, - contentType: input.contentType, - }) - ) - - if (uploadFileData.id) { - const uploadFileId = uploadFileData.id - const uploadFilePathName = generateUploadFilePathName( - uploadFileId, - fileName - ) - const uploadSignedUrl = await generateUploadSignedUrl( - uploadFilePathName, - input.contentType - ) - - // If this is a file URL, we swap in a special URL - const attachmentUrl = `https://omnivore.app/attachments/${uploadFilePathName}` - if (isFileUrl(input.url)) { - await authTrx(async (tx) => { - await tx.getRepository(UploadFile).update(uploadFileId, { - url: attachmentUrl, - status: UploadFileStatus.Initialized, - }) - }) - } - - let createdItemId: string | undefined = undefined - if (input.createPageEntry) { - // If we have a file:// URL, don't try to match it - // and create a copy of the item, just create a - // new item. - const item = await findLibraryItemByUrl(input.url, uid) - if (item) { - await updateLibraryItem( - item.id, - { - state: LibraryItemState.Processing, - }, - uid - ) - createdItemId = item.id - } else { - const itemType = itemTypeForContentType(input.contentType) - const uploadFileId = uploadFileData.id - const item = await createLibraryItem( - { - id: input.clientRequestId || undefined, - originalUrl: isFileUrl(input.url) ? attachmentUrl : input.url, - user: { id: uid }, - title, - readableContent: '', - itemType, - uploadFile: { id: uploadFileData.id }, - slug: generateSlug(uploadFilePathName), - state: LibraryItemState.Processing, - contentReader: contentReaderForLibraryItem(itemType, uploadFileId), - }, - uid - ) - createdItemId = item.id - } - } - - return { - id: uploadFileData.id, - uploadSignedUrl, - createdPageId: createdItemId, - } - } else { - return { errorCodes: [UploadFileRequestErrorCode.FailedCreate] } - } + return uploadFile(input, uid) }) diff --git a/packages/api/src/routers/svc/content.ts b/packages/api/src/routers/svc/content.ts index f32d4078b..c545b4f32 100644 --- a/packages/api/src/routers/svc/content.ts +++ b/packages/api/src/routers/svc/content.ts @@ -13,7 +13,6 @@ export function contentServiceRouter() { const router = express.Router() router.post('/search', async (req, res) => { - logger.info('search req', req) const { message: msgStr, expired } = readPushSubscription(req) logger.info('read pubsub message', { msgStr, expired }) diff --git a/packages/api/src/routers/svc/following.ts b/packages/api/src/routers/svc/following.ts index 261dbf4ee..834d6c531 100644 --- a/packages/api/src/routers/svc/following.ts +++ b/packages/api/src/routers/svc/following.ts @@ -53,15 +53,13 @@ export function followingServiceRouter() { const router = express.Router() router.post('/save', async (req, res) => { - logger.info('save following item request', req.body) - if (req.query.token !== process.env.PUBSUB_VERIFICATION_TOKEN) { - console.log('query does not include valid token') + logger.info('query does not include valid token') return res.sendStatus(403) } if (!isSaveFollowingItemRequest(req.body)) { - console.error('Invalid request body', req.body) + logger.error('Invalid request body', req.body) return res.status(400).send('INVALID_REQUEST_BODY') } diff --git a/packages/api/src/routers/svc/links.ts b/packages/api/src/routers/svc/links.ts index 7d6e1d0db..05d69225d 100644 --- a/packages/api/src/routers/svc/links.ts +++ b/packages/api/src/routers/svc/links.ts @@ -29,7 +29,7 @@ const getPruneMessage = (msgStr: string): PruneMessage => { return obj } } catch (err) { - console.log('error deserializing event: ', { msgStr, err }) + logger.error('error deserializing event: ', { msgStr, err }) } // default to prune following folder items older than 30 days @@ -43,7 +43,6 @@ export function linkServiceRouter() { const router = express.Router() router.post('/create', async (req, res) => { - logger.info('create link req', req) const { message: msgStr, expired } = readPushSubscription(req) logger.info('read pubsub message', { msgStr, expired }) @@ -71,7 +70,6 @@ export function linkServiceRouter() { userId: msg.userId, url: msg.url, }) - logger.info('create link request', request) res.status(200).send(request) } catch (err) { @@ -81,8 +79,6 @@ export function linkServiceRouter() { }) router.post('/prune', async (req, res) => { - logger.info('prune expired items in folder') - const { message: msgStr, expired } = readPushSubscription(req) if (!msgStr) { diff --git a/packages/api/src/routers/svc/rss_feed.ts b/packages/api/src/routers/svc/rss_feed.ts index 7b2ef2ccb..4f7b345d8 100644 --- a/packages/api/src/routers/svc/rss_feed.ts +++ b/packages/api/src/routers/svc/rss_feed.ts @@ -23,11 +23,11 @@ export function rssFeedRouter() { if (redisDataSource.workerRedisClient) { await queueRSSRefreshAllFeedsJob() } else { - console.log('unable to fetchAll feeds, redis is not configured') + logger.info('unable to fetchAll feeds, redis is not configured') return res.status(500).send('Expired') } } catch (error) { - logger.info('error fetching rss feeds', error) + logger.error('error fetching rss feeds', error) return res.status(500).send('Internal Server Error') } diff --git a/packages/api/src/routers/svc/user.ts b/packages/api/src/routers/svc/user.ts index cf9519c69..ec6857ff0 100644 --- a/packages/api/src/routers/svc/user.ts +++ b/packages/api/src/routers/svc/user.ts @@ -23,7 +23,7 @@ const getCleanupMessage = (msgStr: string): CleanupMessage => { return obj } } catch (err) { - console.log('error deserializing event: ', { msgStr, err }) + logger.error('error deserializing event: ', { msgStr, err }) } return { diff --git a/packages/api/src/schema.ts b/packages/api/src/schema.ts index 47720b676..d18b91012 100755 --- a/packages/api/src/schema.ts +++ b/packages/api/src/schema.ts @@ -545,6 +545,9 @@ const schema = gql` state: ArticleSavingRequestStatus labels: [CreateLabelInput!] folder: String + savedAt: Date + publishedAt: Date + subscription: String } input ParseResult { @@ -1686,6 +1689,9 @@ const schema = gql` autoAddToLibrary: Boolean fetchContent: Boolean! folder: String! + mostRecentItemDate: Date + refreshedAt: Date + failedAt: Date } enum SubscriptionStatus { @@ -2597,7 +2603,6 @@ const schema = gql` id: ID! name: String description: String - lastFetchedAt: Date lastFetchedChecksum: String status: SubscriptionStatus scheduledAt: Date @@ -2605,6 +2610,9 @@ const schema = gql` autoAddToLibrary: Boolean fetchContent: Boolean folder: String + refreshedAt: Date + mostRecentItemDate: Date + failedAt: Date } union UpdateSubscriptionResult = diff --git a/packages/api/src/server.ts b/packages/api/src/server.ts index e52b0312b..58a7e4d2b 100755 --- a/packages/api/src/server.ts +++ b/packages/api/src/server.ts @@ -159,7 +159,7 @@ const main = async (): Promise => { await appDataSource.initialize() // redis is optional for the API server - if (env.redis.url) { + if (env.redis.cache.url) { await redisDataSource.initialize() } diff --git a/packages/api/src/services/labels.ts b/packages/api/src/services/labels.ts index 46ec8eb0a..564a1e2da 100644 --- a/packages/api/src/services/labels.ts +++ b/packages/api/src/services/labels.ts @@ -5,7 +5,6 @@ import { Label } from '../entity/label' import { createPubSubClient, EntityType, PubsubClient } from '../pubsub' import { authTrx } from '../repository' import { CreateLabelInput, labelRepository } from '../repository/label' -import { libraryItemRepository } from '../repository/library_item' type AddLabelsToLibraryItemEvent = { pageId: string @@ -124,43 +123,28 @@ export const saveLabelsInLibraryItem = async ( } export const addLabelsToLibraryItem = async ( - labels: Label[], + labelIds: string[], libraryItemId: string, userId: string, - source: LabelSource = 'user', - pubsub = createPubSubClient() + source: LabelSource = 'user' ) => { await authTrx( async (tx) => { - const libraryItem = await tx - .withRepository(libraryItemRepository) - .findOneByOrFail({ id: libraryItemId, user: { id: userId } }) - - if (libraryItem.labels) { - labels.push(...libraryItem.labels) - } - - // save new labels - await tx.getRepository(EntityLabel).save( - labels.map((l) => ({ - labelId: l.id, - libraryItemId, - source, - })) + await tx.query( + `INSERT INTO omnivore.entity_labels (label_id, library_item_id, source) + SELECT id, $1, $2 FROM omnivore.labels + WHERE id = ANY($3) + AND NOT EXISTS ( + SELECT 1 FROM omnivore.entity_labels + WHERE label_id = labels.id + AND library_item_id = $1 + )`, + [libraryItemId, source, labelIds] ) }, undefined, userId ) - - if (source === 'user') { - // create pubsub event - await pubsub.entityCreated( - EntityType.LABEL, - { pageId: libraryItemId, labels, source }, - userId - ) - } } export const saveLabelsInHighlight = async ( diff --git a/packages/api/src/services/library_item.ts b/packages/api/src/services/library_item.ts index 11a7ee92a..73e9fde77 100644 --- a/packages/api/src/services/library_item.ts +++ b/packages/api/src/services/library_item.ts @@ -698,7 +698,8 @@ export const updateLibraryItem = async ( id: string, libraryItem: QueryDeepPartialEntity, userId: string, - pubsub = createPubSubClient() + pubsub = createPubSubClient(), + skipPubSub = false ): Promise => { const updatedLibraryItem = await authTrx( async (tx) => { @@ -726,6 +727,10 @@ export const updateLibraryItem = async ( userId ) + if (skipPubSub) { + return updatedLibraryItem + } + await pubsub.entityUpdated>( EntityType.PAGE, { diff --git a/packages/api/src/services/reports.ts b/packages/api/src/services/reports.ts index f7829dadf..e2aa573d5 100644 --- a/packages/api/src/services/reports.ts +++ b/packages/api/src/services/reports.ts @@ -33,18 +33,19 @@ export const saveContentDisplayReport = async ( ${report.user.id} for URL: ${report.originalUrl} ${report.reportComment}` - logger.info(message) - - if (!env.dev.isLocal) { - // If we are in the local environment, just log a message, otherwise email the report - await sendEmail({ - to: env.sender.feedback, - subject: 'New content display report', - text: message, - from: env.sender.message, - }) + // If we are in the local environment, just log a message, otherwise email the report + if (env.dev.isLocal) { + logger.info(message) + return !!report } + await sendEmail({ + to: env.sender.feedback, + subject: 'New content display report', + text: message, + from: env.sender.message, + }) + return !!report } diff --git a/packages/api/src/services/rules.ts b/packages/api/src/services/rules.ts index 01f86c8ce..5f27a3839 100644 --- a/packages/api/src/services/rules.ts +++ b/packages/api/src/services/rules.ts @@ -1,6 +1,6 @@ -import { ILike } from 'typeorm' -import { Rule, RuleAction } from '../entity/rule' -import { authTrx } from '../repository' +import { ArrayContainedBy, ArrayContains, ILike } from 'typeorm' +import { Rule, RuleAction, RuleEventType } from '../entity/rule' +import { authTrx, getRepository } from '../repository' export const createRule = async ( userId: string, @@ -53,3 +53,14 @@ export const deleteRules = async (userId: string) => { userId ) } + +export const findEnabledRules = async ( + userId: string, + eventType: RuleEventType +) => { + return getRepository(Rule).findBy({ + user: { id: userId }, + enabled: true, + eventTypes: ArrayContainedBy([eventType]), + }) +} diff --git a/packages/api/src/services/save_email.ts b/packages/api/src/services/save_email.ts index 092c2b98f..8ecd25d53 100644 --- a/packages/api/src/services/save_email.ts +++ b/packages/api/src/services/save_email.ts @@ -1,5 +1,5 @@ import { LibraryItem, LibraryItemState } from '../entity/library_item' -import { enqueueThumbnailTask } from '../utils/createTask' +import { enqueueThumbnailJob } from '../utils/createTask' import { cleanUrl, generateSlug, @@ -53,7 +53,6 @@ export const saveEmail = async ( // can leave this empty for now }, }, - null, true ) @@ -76,7 +75,6 @@ export const saveEmail = async ( existingLibraryItem.id, input.userId ) - logger.info('updated page from email', updatedLibraryItem) return updatedLibraryItem } @@ -133,12 +131,14 @@ export const saveEmail = async ( await updateReceivedEmail(input.receivedEmailId, 'article', input.userId) - // create a task to update thumbnail and pre-cache all images - try { - const taskId = await enqueueThumbnailTask(input.userId, slug) - logger.info('Created thumbnail task', { taskId }) - } catch (e) { - logger.error('Failed to create thumbnail task', e) + if (!newLibraryItem.thumbnail) { + // create a task to update thumbnail and pre-cache all images + try { + const job = await enqueueThumbnailJob(input.userId, newLibraryItem.id) + logger.info('Created thumbnail job', { taskId: job }) + } catch (e) { + logger.error('Failed to create thumbnail job', e) + } } return newLibraryItem diff --git a/packages/api/src/services/save_file.ts b/packages/api/src/services/save_file.ts index e6c58148b..a004f1558 100644 --- a/packages/api/src/services/save_file.ts +++ b/packages/api/src/services/save_file.ts @@ -14,6 +14,7 @@ export const saveFile = async ( const uploadFile = await findUploadFileById(input.uploadFileId) if (!uploadFile) { return { + __typename: 'SaveError', errorCodes: [SaveErrorCode.Unauthorized], } } @@ -24,26 +25,30 @@ export const saveFile = async ( if (!uploadFileData) { return { + __typename: 'SaveError', errorCodes: [SaveErrorCode.Unknown], } } - if (input.state || input.folder) { - await updateLibraryItem( - input.clientRequestId, - { - state: (input.state as unknown as LibraryItemState) || undefined, - folder: input.folder || undefined, - }, - user.id - ) - } + await updateLibraryItem( + input.clientRequestId, + { + state: + (input.state as unknown as LibraryItemState) || + LibraryItemState.Succeeded, + folder: input.folder || undefined, + savedAt: input.savedAt ? new Date(input.savedAt) : undefined, + publishedAt: input.publishedAt ? new Date(input.publishedAt) : undefined, + }, + user.id + ) // add labels to item await createAndSaveLabelsInLibraryItem( input.clientRequestId, user.id, - input.labels + input.labels, + input.subscription ) return { diff --git a/packages/api/src/services/save_page.ts b/packages/api/src/services/save_page.ts index bb887fd83..52c814acf 100644 --- a/packages/api/src/services/save_page.ts +++ b/packages/api/src/services/save_page.ts @@ -13,12 +13,11 @@ import { SaveResult, } from '../generated/graphql' import { authTrx } from '../repository' -import { enqueueThumbnailTask } from '../utils/createTask' +import { enqueueThumbnailJob } from '../utils/createTask' import { cleanUrl, generateSlug, stringToHash, - TWEET_URL_REGEX, validatedDate, wordsCount, } from '../utils/helpers' @@ -32,7 +31,7 @@ import { createLibraryItem, updateLibraryItem } from './library_item' // where we can use APIs to fetch their underlying content. const FORCE_PUPPETEER_URLS = [ - TWEET_URL_REGEX, + /twitter\.com\/(?:#!\/)?(\w+)\/status(?:es)?\/(\d+)(?:\/.*)?/, /^((?:https?:)?\/\/)?((?:www|m)\.)?((?:youtube\.com|youtu.be))(\/(?:[\w-]+\?v=|embed\/|v\/)?)([\w-]+)(\S+)?$/, ] const ALREADY_PARSED_SOURCES = [ @@ -58,7 +57,9 @@ const createSlug = (url: string, title?: string | null | undefined) => { const shouldParseInBackend = (input: SavePageInput): boolean => { return ( ALREADY_PARSED_SOURCES.indexOf(input.source) === -1 && - FORCE_PUPPETEER_URLS.some((regex) => regex.test(input.url)) + FORCE_PUPPETEER_URLS.some((regex) => { + return regex.test(input.url) + }) ) } @@ -66,17 +67,13 @@ export const savePage = async ( input: SavePageInput, user: User ): Promise => { - const parseResult = await parsePreparedContent( - input.url, - { - document: input.originalContent, - pageInfo: { - title: input.title, - canonicalUrl: input.url, - }, + const parseResult = await parsePreparedContent(input.url, { + document: input.originalContent, + pageInfo: { + title: input.title, + canonicalUrl: input.url, }, - input.parseResult - ) + }) const [newSlug, croppedPathname] = createSlug(input.url, input.title) let slug = newSlug let clientRequestId = input.clientRequestId @@ -114,6 +111,7 @@ export const savePage = async ( }) } catch (e) { return { + __typename: 'SaveError', errorCodes: [SaveErrorCode.Unknown], message: 'Failed to create page save request', } @@ -171,10 +169,10 @@ export const savePage = async ( if (!isImported && !parseResult.parsedContent?.previewImage) { try { // create a task to update thumbnail and pre-cache all images - const taskId = await enqueueThumbnailTask(user.id, slug) - logger.info('Created thumbnail task', { taskId }) + const job = await enqueueThumbnailJob(user.id, clientRequestId) + logger.info('Created thumbnail job', { job }) } catch (e) { - logger.error('Failed to create thumbnail task', e) + logger.error('Failed to enqueue thumbnail job', e) } } @@ -185,11 +183,14 @@ export const savePage = async ( libraryItem: { id: clientRequestId }, } - if (!(await createHighlight(highlight, clientRequestId, user.id))) { - return { - errorCodes: [SaveErrorCode.EmbeddedHighlightFailed], - message: 'Failed to save highlight', - } + try { + await createHighlight(highlight, clientRequestId, user.id) + } catch (error) { + logger.error('Failed to create highlight', { + highlight, + clientRequestId, + userId: user.id, + }) } } @@ -239,7 +240,7 @@ export const parsedContentToLibraryItem = ({ rssFeedUrl?: string | null folder?: string | null }): DeepPartial & { originalUrl: string } => { - console.log('save_page: state', { url, state, itemId }) + logger.info('save_page: state', { url, state, itemId }) return { id: itemId || undefined, slug, diff --git a/packages/api/src/services/subscriptions.ts b/packages/api/src/services/subscriptions.ts index fcf25af01..22be8c2f4 100644 --- a/packages/api/src/services/subscriptions.ts +++ b/packages/api/src/services/subscriptions.ts @@ -103,7 +103,7 @@ export const saveSubscription = async ({ unsubscribeHttpUrl, unsubscribeMailTo, icon, - lastFetchedAt: new Date(), + refreshedAt: new Date(), } const existingSubscription = await getSubscriptionByName(name, userId) @@ -199,7 +199,7 @@ export const createSubscription = async ( newsletterEmail, status, unsubscribeMailTo, - lastFetchedAt: new Date(), + refreshedAt: new Date(), type: subscriptionType, url, }) diff --git a/packages/api/src/services/update_subscription.ts b/packages/api/src/services/update_subscription.ts index 1106e3043..bcc077291 100644 --- a/packages/api/src/services/update_subscription.ts +++ b/packages/api/src/services/update_subscription.ts @@ -1,8 +1,4 @@ -import { Subscription } from '../entity/subscription' -import { - SubscriptionStatus, - UpdateSubscriptionInput, -} from '../generated/graphql' +import { Subscription, SubscriptionStatus } from '../entity/subscription' import { getRepository } from '../repository' const ensureOwns = async (userId: string, subscriptionId: string) => { @@ -23,11 +19,13 @@ type UpdateSubscriptionData = { fetchContent?: boolean | null folder?: string | null isPrivate?: boolean | null - lastFetchedAt?: Date | null + mostRecentItemDate?: Date | null lastFetchedChecksum?: string | null name?: string | null scheduledAt?: Date | null status?: SubscriptionStatus | null + refreshedAt?: Date | null + failedAt?: Date | null } export const updateSubscription = async ( @@ -42,22 +40,43 @@ export const updateSubscription = async ( id: subscriptionId, name: newData.name || undefined, description: newData.description || undefined, - lastFetchedAt: newData.lastFetchedAt - ? new Date(newData.lastFetchedAt) - : undefined, + mostRecentItemDate: newData.mostRecentItemDate || undefined, + refreshedAt: newData.refreshedAt || undefined, lastFetchedChecksum: newData.lastFetchedChecksum || undefined, status: newData.status || undefined, - scheduledAt: newData.scheduledAt - ? new Date(newData.scheduledAt) - : undefined, + scheduledAt: newData.scheduledAt || undefined, + failedAt: newData.failedAt || undefined, autoAddToLibrary: newData.autoAddToLibrary ?? undefined, isPrivate: newData.isPrivate ?? undefined, fetchContent: newData.fetchContent ?? undefined, folder: newData.folder ?? undefined, }) - return await getRepository(Subscription).findOneByOrFail({ + return await repo.findOneByOrFail({ id: subscriptionId, user: { id: userId }, }) } + +export const updateSubscriptions = async ( + subscriptionIds: string[], + newData: UpdateSubscriptionData +) => { + return getRepository(Subscription).save( + subscriptionIds.map((id) => ({ + id, + name: newData.name || undefined, + description: newData.description || undefined, + mostRecentItemDate: newData.mostRecentItemDate || undefined, + refreshedAt: newData.refreshedAt || undefined, + lastFetchedChecksum: newData.lastFetchedChecksum || undefined, + status: newData.status || undefined, + scheduledAt: newData.scheduledAt || undefined, + failedAt: newData.failedAt || undefined, + autoAddToLibrary: newData.autoAddToLibrary ?? undefined, + isPrivate: newData.isPrivate ?? undefined, + fetchContent: newData.fetchContent ?? undefined, + folder: newData.folder ?? undefined, + })) + ) +} diff --git a/packages/api/src/services/upload_file.ts b/packages/api/src/services/upload_file.ts index c281a3384..1df0ab97f 100644 --- a/packages/api/src/services/upload_file.ts +++ b/packages/api/src/services/upload_file.ts @@ -1,5 +1,35 @@ +import normalizeUrl from 'normalize-url' +import path from 'path' +import { LibraryItemState } from '../entity/library_item' import { UploadFile } from '../entity/upload_file' +import { + PageType, + UploadFileRequestErrorCode, + UploadFileRequestInput, + UploadFileStatus, +} from '../generated/graphql' import { authTrx, getRepository } from '../repository' +import { generateSlug } from '../utils/helpers' +import { logger } from '../utils/logger' +import { + contentReaderForLibraryItem, + generateUploadFilePathName, + generateUploadSignedUrl, +} from '../utils/uploads' +import { validateUrl } from './create_page_save_request' +import { createLibraryItem } from './library_item' + +const isFileUrl = (url: string): boolean => { + const parsedUrl = new URL(url) + return parsedUrl.protocol == 'file:' +} + +export const itemTypeForContentType = (contentType: string) => { + if (contentType == 'application/epub+zip') { + return PageType.Book + } + return PageType.File +} export const findUploadFileById = async (id: string) => { return getRepository(UploadFile).findOne({ @@ -22,3 +52,100 @@ export const setFileUploadComplete = async (id: string, userId?: string) => { userId ) } + +export const uploadFile = async ( + input: UploadFileRequestInput, + uid: string +) => { + let title: string + let fileName: string + try { + const url = normalizeUrl(new URL(input.url).href, { + stripHash: true, + stripWWW: false, + }) + title = decodeURI(path.basename(new URL(url).pathname, '.pdf')) + fileName = decodeURI(path.basename(new URL(url).pathname)).replace( + /[^a-zA-Z0-9-_.]/g, + '' + ) + + if (!fileName) { + fileName = 'content.pdf' + } + + if (!isFileUrl(url)) { + try { + validateUrl(url) + } catch (error) { + logger.info('illegal file input url', error) + return { + errorCodes: [UploadFileRequestErrorCode.BadInput], + } + } + } + } catch { + return { + errorCodes: [UploadFileRequestErrorCode.BadInput], + } + } + + const uploadFileData = await authTrx((t) => + t.getRepository(UploadFile).save({ + url: input.url, + user: { id: uid }, + fileName, + status: UploadFileStatus.Initialized, + contentType: input.contentType, + }) + ) + const uploadFileId = uploadFileData.id + const uploadFilePathName = generateUploadFilePathName(uploadFileId, fileName) + const uploadSignedUrl = await generateUploadSignedUrl( + uploadFilePathName, + input.contentType + ) + + // If this is a file URL, we swap in a special URL + const attachmentUrl = `https://omnivore.app/attachments/${uploadFilePathName}` + if (isFileUrl(input.url)) { + await authTrx(async (tx) => { + await tx.getRepository(UploadFile).update(uploadFileId, { + url: attachmentUrl, + status: UploadFileStatus.Initialized, + }) + }) + } + + const itemType = itemTypeForContentType(input.contentType) + if (input.createPageEntry) { + // If we have a file:// URL, don't try to match it + // and create a copy of the item, just create a + // new item. + const item = await createLibraryItem( + { + id: input.clientRequestId || undefined, + originalUrl: isFileUrl(input.url) ? attachmentUrl : input.url, + user: { id: uid }, + title, + readableContent: '', + itemType, + uploadFile: { id: uploadFileData.id }, + slug: generateSlug(uploadFilePathName), + state: LibraryItemState.Processing, + contentReader: contentReaderForLibraryItem(itemType, uploadFileId), + }, + uid + ) + return { + id: uploadFileId, + uploadSignedUrl, + createdPageId: item.id, + } + } + + return { + id: uploadFileId, + uploadSignedUrl, + } +} diff --git a/packages/api/src/services/user.ts b/packages/api/src/services/user.ts index 1a4dc58d1..1a74500bb 100644 --- a/packages/api/src/services/user.ts +++ b/packages/api/src/services/user.ts @@ -1,9 +1,15 @@ +import { Notification } from 'firebase-admin/messaging' import { DeepPartial, FindOptionsWhere, In } from 'typeorm' import { Profile } from '../entity/profile' import { StatusType, User } from '../entity/user' import { authTrx, getRepository, queryBuilderToRawSql } from '../repository' import { userRepository } from '../repository/user' import { SetClaimsRole } from '../utils/dictionary' +import { + PushNotificationType, + sendMulticastPushNotifications, +} from '../utils/sendNotification' +import { findDeviceTokensByUserId } from './user_device_tokens' export const deleteUser = async (userId: string) => { await authTrx( @@ -120,3 +126,23 @@ export const batchDelete = async (criteria: FindOptionsWhere) => { SetClaimsRole.ADMIN ) } + +export const sendPushNotifications = async ( + userId: string, + notification: Notification, + notificationType: PushNotificationType, + data?: { [key: string]: string } +) => { + const tokens = await findDeviceTokensByUserId(userId) + if (tokens.length === 0) { + throw new Error('No device tokens found') + } + + const message = { + notification, + data, + tokens: tokens.map((token) => token.token), + } + + return sendMulticastPushNotifications(userId, message, notificationType) +} diff --git a/packages/api/src/util.ts b/packages/api/src/util.ts index 691b58063..3f1570c26 100755 --- a/packages/api/src/util.ts +++ b/packages/api/src/util.ts @@ -4,6 +4,11 @@ import * as dotenv from 'dotenv' import os from 'os' +interface redisConfig { + url?: string + cert?: string +} + export interface BackendEnv { pg: { host: string @@ -105,8 +110,8 @@ export interface BackendEnv { } } redis: { - url?: string - cert?: string + mq: redisConfig + cache: redisConfig } } @@ -156,6 +161,8 @@ const nullableEnvVars = [ 'SUBSCRIPTION_FEED_MAX', 'REDIS_URL', 'REDIS_CERT', + 'MQ_REDIS_URL', + 'MQ_REDIS_CERT', 'IMPORTER_METRICS_COLLECTOR_URL', 'INTERNAL_API_URL', ] // Allow some vars to be null/empty @@ -295,8 +302,14 @@ export function getEnv(): BackendEnv { }, } const redis = { - url: parse('REDIS_URL'), - cert: parse('REDIS_CERT')?.replace(/\\n/g, '\n'), // replace \n with new line + mq: { + url: parse('MQ_REDIS_URL'), + cert: parse('MQ_REDIS_CERT')?.replace(/\\n/g, '\n'), // replace \n with new line + }, + cache: { + url: parse('REDIS_URL'), + cert: parse('REDIS_CERT')?.replace(/\\n/g, '\n'), // replace \n with new line + }, } return { diff --git a/packages/api/src/utils/createTask.ts b/packages/api/src/utils/createTask.ts index 410fe7fc7..4e3ed31ce 100644 --- a/packages/api/src/utils/createTask.ts +++ b/packages/api/src/utils/createTask.ts @@ -6,23 +6,25 @@ import { google } from '@google-cloud/tasks/build/protos/protos' import axios from 'axios' import { nanoid } from 'nanoid' import { DeepPartial } from 'typeorm' +import { v4 as uuid } from 'uuid' import { ImportItemState } from '../entity/integration' import { Recommendation } from '../entity/recommendation' -import { DEFAULT_SUBSCRIPTION_FOLDER } from '../entity/subscription' import { env } from '../env' import { ArticleSavingRequestStatus, CreateLabelInput, } from '../generated/graphql' +import { THUMBNAIL_JOB } from '../jobs/find_thumbnail' +import { queueRSSRefreshFeedJob } from '../jobs/rss/refreshAllFeeds' +import { TriggerRuleJobData, TRIGGER_RULE_JOB_NAME } from '../jobs/trigger_rule' +import { getBackendQueue } from '../queue-processor' +import { redisDataSource } from '../redis_data_source' import { signFeatureToken } from '../services/features' -import { generateVerificationToken, OmnivoreAuthorizationHeader } from './auth' +import { OmnivoreAuthorizationHeader } from './auth' import { CreateTaskError } from './errors' +import { stringToHash } from './helpers' import { logger } from './logger' import View = google.cloud.tasks.v2.Task.View -import { stringToHash } from './helpers' -import { queueRSSRefreshFeedJob } from '../jobs/rss/refreshAllFeeds' -import { redisDataSource } from '../redis_data_source' -import { v4 as uuid } from 'uuid' // Instantiates a client. const client = new CloudTasksClient() @@ -65,7 +67,7 @@ const createHttpTaskWithToken = async ({ > => { // If there is no Google Cloud Project Id exposed, it means that we are in local environment if (env.dev.isLocal || !project) { - console.error( + logger.error( 'error: attempting to create a cloud task but not running in google cloud.' ) return null @@ -112,7 +114,7 @@ const createHttpTaskWithToken = async ({ } try { - return client.createTask({ parent, task }) + return await client.createTask({ parent, task }) } catch (error) { logError(error) return null @@ -170,7 +172,6 @@ export const createAppEngineTask = async ({ } logger.info('Sending task:') - logger.info(task) // Send create task request. const request = { parent: parent, task: task } const [response] = await client.createTask(request) @@ -578,59 +579,29 @@ export const enqueueExportToIntegration = async ( return createdTasks[0].name } -export const enqueueThumbnailTask = async ( +export const enqueueThumbnailJob = async ( userId: string, - slug: string -): Promise => { - const { GOOGLE_CLOUD_PROJECT } = process.env + libraryItemId: string +) => { + const queue = await getBackendQueue() + if (!queue) { + return undefined + } const payload = { userId, - slug, + libraryItemId, } - - const headers = { - Cookie: `auth=${generateVerificationToken({ id: userId })}`, - } - - // If there is no Google Cloud Project Id exposed, it means that we are in local environment - if (env.dev.isLocal || !GOOGLE_CLOUD_PROJECT) { - if (env.queue.thumbnailTaskHandlerUrl) { - // Calling the handler function directly. - setTimeout(() => { - axios - .post(env.queue.thumbnailTaskHandlerUrl, payload, { - headers, - }) - .catch((error) => { - logError(error) - }) - }, 0) - } - return '' - } - - const createdTasks = await createHttpTaskWithToken({ - payload, - taskHandlerUrl: env.queue.thumbnailTaskHandlerUrl, - requestHeaders: headers, - queue: 'omnivore-thumbnail-queue', + return queue.add(THUMBNAIL_JOB, payload, { + priority: 100, + attempts: 1, }) - - if (!createdTasks || !createdTasks[0].name) { - logger.error(`Unable to get the name of the task`, { - payload, - createdTasks, - }) - throw new CreateTaskError(`Unable to get the name of the task`) - } - return createdTasks[0].name } export interface RssSubscriptionGroup { url: string subscriptionIds: string[] userIds: string[] - fetchedDates: (Date | null)[] + mostRecentItemDates: (Date | null)[] scheduledDates: Date[] checksums: (string | null)[] fetchContents: boolean[] @@ -648,7 +619,7 @@ export const enqueueRssFeedFetch = async ( }, subscriptionIds: subscriptionGroup.subscriptionIds, feedUrl: subscriptionGroup.url, - lastFetchedTimestamps: subscriptionGroup.fetchedDates.map( + mostRecentItemDates: subscriptionGroup.mostRecentItemDates.map( (timestamp) => timestamp?.getTime() || 0 ), // unix timestamp in milliseconds lastFetchedChecksums: subscriptionGroup.checksums, @@ -677,4 +648,16 @@ export const enqueueRssFeedFetch = async ( } } +export const enqueueTriggerRuleJob = async (data: TriggerRuleJobData) => { + const queue = await getBackendQueue() + if (!queue) { + return undefined + } + + return queue.add(TRIGGER_RULE_JOB_NAME, data, { + removeOnComplete: true, + removeOnFail: true, + }) +} + export default createHttpTaskWithToken diff --git a/packages/api/src/utils/helpers.ts b/packages/api/src/utils/helpers.ts index 5b7ca9b83..c53b1f630 100644 --- a/packages/api/src/utils/helpers.ts +++ b/packages/api/src/utils/helpers.ts @@ -22,11 +22,9 @@ import { PageType, Profile, Recommendation, - ResolverFn, SearchItem, } from '../generated/graphql' import { createPubSubClient } from '../pubsub' -import { Claims, WithDataSourcesContext } from '../resolvers/types' import { validateUrl } from '../services/create_page_save_request' import { updateLibraryItem } from '../services/library_item' import { Merge } from '../util' @@ -391,17 +389,10 @@ export const setRecentlySavedItemInRedis = async ( url: string ) => { // save the url in redis for 26 hours so rss-feeder won't try to re-save it - if (!redisClient) { - console.info( - 'not setting recently saved item because redis is not configured' - ) - return - } - // save the url in redis for 8 hours so rss-feeder won't try to re-save it const redisKey = `recent-saved-item:${userId}:${url}` const ttlInSeconds = 60 * 60 * 26 try { - return redisClient.set(redisKey, 1, 'EX', ttlInSeconds, 'NX') + return await redisClient.set(redisKey, 1, 'EX', ttlInSeconds, 'NX') } catch (error) { logger.error('error setting recently saved item in redis', { redisKey, diff --git a/packages/api/src/utils/logger.ts b/packages/api/src/utils/logger.ts index 99daf5a7b..f4019893d 100644 --- a/packages/api/src/utils/logger.ts +++ b/packages/api/src/utils/logger.ts @@ -34,11 +34,9 @@ export class CustomTypeOrmLogger } logQuery(query: string, parameters?: any[], queryRunner?: QueryRunner) { - this.logger.info( - `query: ${query} -- PARAMETERS: ${super.stringifyParams( - parameters || [] - )}` - ) + this.logger.info(query, { + parameters, + }) } log( @@ -133,10 +131,8 @@ const truncateObjectDeep = (object: any, length: number): any => { class GcpLoggingTransport extends LoggingWinston { log(info: any, callback: (err: Error | null, apiResponse?: any) => void) { - const sizeInfo = jsonStringify(info).length - if (sizeInfo > MAX_LOG_SIZE) { - info = truncateObjectDeep(info, 500) as never // the max length for string values is 500 - } + // reduce the size of the log entry by truncating any string values to 500 characters + info = truncateObjectDeep(info, 500) as never super.log(info, callback) } } diff --git a/packages/api/src/utils/parser.ts b/packages/api/src/utils/parser.ts index 54373baea..a52d5968e 100644 --- a/packages/api/src/utils/parser.ts +++ b/packages/api/src/utils/parser.ts @@ -223,7 +223,6 @@ const getReadabilityResult = async ( export const parsePreparedContent = async ( url: string, preparedDocument: PreparedDocumentInput, - parseResult?: Readability.ParseResult | null, isNewsletter?: boolean, allowRetry = true ): Promise => { @@ -232,12 +231,8 @@ export const parsePreparedContent = async ( labels: { source: 'parsePreparedContent' }, } - // If we have a parse result, use it - let article = parseResult || null - let highlightData = undefined - const { document, pageInfo } = preparedDocument - - if (!document) { + const { document: domContent, pageInfo } = preparedDocument + if (!domContent) { logger.info('No document') return { canonicalUrl: url, @@ -257,142 +252,147 @@ export const parsePreparedContent = async ( return { canonicalUrl: url, parsedContent: null, - domContent: document, + domContent, pageType: PageType.Unknown, } } - let dom: Document | null = null + const { title: pageInfoTitle, canonicalUrl } = pageInfo + + let parsedContent: Readability.ParseResult | null = null + let pageType = PageType.Unknown + let highlightData = undefined try { - dom = parseHTML(document).document + const document = parseHTML(domContent).document + pageType = parseOriginalContent(document) - if (!article) { - // Attempt to parse the article - // preParse content - dom = (await preParseContent(url, dom)) || dom + // Run readability + await preParseContent(url, document) - article = await getReadabilityResult(url, document, dom, isNewsletter) - } + parsedContent = await getReadabilityResult( + url, + domContent, + document, + isNewsletter + ) - if (!article?.textContent && allowRetry) { - const newDocument = { - ...preparedDocument, - document: '' + document + '', // wrap in body + if (!parsedContent || !parsedContent.content) { + logger.info('No parsed content') + + if (allowRetry) { + logger.info('Retrying with content wrapped in html body') + + const newDocument = { + ...preparedDocument, + document: '' + domContent + '', // wrap in body + } + return parsePreparedContent(url, newDocument, isNewsletter, false) + } + + return { + canonicalUrl, + parsedContent, + domContent, + pageType, } - return parsePreparedContent( - url, - newDocument, - parseResult, - isNewsletter, - false - ) } + // use title if not found after running readability + if (!parsedContent.title && pageInfoTitle) { + parsedContent.title = pageInfoTitle + } + + const newDocumentElement = parsedContent.documentElement // Format code blocks // TODO: we probably want to move this type of thing // to the handlers, and have some concept of postHandle - if (article?.content) { - const articleDom = parseHTML(article.content).document - const codeBlocks = articleDom.querySelectorAll( - 'code, pre[class^="prism-"], pre[class^="language-"]' - ) - if (codeBlocks.length > 0) { - codeBlocks.forEach((e) => { - if (e.textContent) { - const att = hljs.highlightAuto(e.textContent) - const code = articleDom.createElement('code') - const langClass = - `hljs language-${att.language}` + - (att.second_best?.language - ? ` language-${att.second_best?.language}` - : '') - code.setAttribute('class', langClass) - code.innerHTML = att.value - e.replaceWith(code) - } + const codeBlocks = newDocumentElement.querySelectorAll( + 'pre[class^="prism-"], pre[class^="language-"], code' + ) + codeBlocks.forEach((e) => { + if (!e.textContent) { + return e.parentNode?.removeChild(e) + } + + // replace
or

or

with \n + e.innerHTML = e.innerHTML.replace(/<(br|p|\/p)>/g, '\n') + + const att = hljs.highlightAuto(e.textContent) + const code = document.createElement('code') + const langClass = + `hljs language-${att.language}` + + (att.second_best?.language + ? ` language-${att.second_best?.language}` + : '') + code.setAttribute('class', langClass) + code.innerHTML = att.value + e.replaceWith(code) + }) + + highlightData = findEmbeddedHighlight(newDocumentElement) + + const ANCHOR_ELEMENTS_BLOCKED_ATTRIBUTES = [ + 'omnivore-highlight-id', + 'data-twitter-tweet-id', + 'data-instagram-id', + ] + + // Get the top level element? + // const pageNode = newDocumentElement.firstElementChild as HTMLElement + const nodesToVisitStack: [HTMLElement] = [newDocumentElement] + const visitedNodeList = [] + + while (nodesToVisitStack.length > 0) { + const currentNode = nodesToVisitStack.pop() + if ( + currentNode?.nodeType !== 1 || + // Avoiding dynamic elements from being counted as anchor-allowed elements + ANCHOR_ELEMENTS_BLOCKED_ATTRIBUTES.some((attrib) => + currentNode.hasAttribute(attrib) + ) + ) { + continue + } + visitedNodeList.push(currentNode) + ;[].slice + .call(currentNode.childNodes) + .reverse() + .forEach(function (node) { + nodesToVisitStack.push(node) }) - article.content = articleDom.documentElement.outerHTML - } - - highlightData = findEmbeddedHighlight(articleDom.documentElement) - - const ANCHOR_ELEMENTS_BLOCKED_ATTRIBUTES = [ - 'omnivore-highlight-id', - 'data-twitter-tweet-id', - 'data-instagram-id', - ] - - // Get the top level element? - const pageNode = articleDom.firstElementChild as HTMLElement - const nodesToVisitStack: [HTMLElement] = [pageNode] - const visitedNodeList = [] - - while (nodesToVisitStack.length > 0) { - const currentNode = nodesToVisitStack.pop() - if ( - currentNode?.nodeType !== 1 || - // Avoiding dynamic elements from being counted as anchor-allowed elements - ANCHOR_ELEMENTS_BLOCKED_ATTRIBUTES.some((attrib) => - currentNode.hasAttribute(attrib) - ) - ) { - continue - } - visitedNodeList.push(currentNode) - ;[].slice - .call(currentNode.childNodes) - .reverse() - .forEach(function (node) { - nodesToVisitStack.push(node) - }) - } - - visitedNodeList.shift() - visitedNodeList.forEach((node, index) => { - // start from index 1, index 0 reserved for anchor unknown. - node.setAttribute('data-omnivore-anchor-idx', (index + 1).toString()) - }) - - article.content = articleDom.documentElement.outerHTML } + visitedNodeList.shift() + visitedNodeList.forEach((node, index) => { + // start from index 1, index 0 reserved for anchor unknown. + node.setAttribute('data-omnivore-anchor-idx', (index + 1).toString()) + }) + + const newHtml = newDocumentElement.outerHTML const newWindow = parseHTML('') const DOMPurify = createDOMPurify(newWindow) DOMPurify.addHook('uponSanitizeElement', domPurifySanitizeHook) - const clean = DOMPurify.sanitize(article?.content || '', DOM_PURIFY_CONFIG) + const cleanHtml = DOMPurify.sanitize(newHtml, DOM_PURIFY_CONFIG) + parsedContent.content = cleanHtml - Object.assign(article || {}, { - content: clean, - title: article?.title, - previewImage: article?.previewImage, - siteName: article?.siteName, - siteIcon: article?.siteIcon, - byline: article?.byline, - language: article?.language, - }) logRecord.parseSuccess = true } catch (error) { - logger.info('Error parsing content', error) + logger.error('Error parsing content', error) + Object.assign(logRecord, { parseSuccess: false, parseError: error, }) } - const { title, canonicalUrl } = pageInfo - - Object.assign(article || {}, { - title: article?.title || title, - }) - - logger.info('parse-article completed') + logger.info('parse-article completed', logRecord) return { - domContent: document, - parsedContent: article, canonicalUrl, - pageType: dom ? parseOriginalContent(dom) : PageType.Unknown, + parsedContent, + domContent, + pageType, highlightData, } } diff --git a/packages/api/src/utils/sendNotification.ts b/packages/api/src/utils/sendNotification.ts index 9c6550653..26adf675c 100644 --- a/packages/api/src/utils/sendNotification.ts +++ b/packages/api/src/utils/sendNotification.ts @@ -60,7 +60,7 @@ export const sendMulticastPushNotifications = async ( }) logger.info('sending multicast message: ', message) - const res = await getMessaging().sendMulticast(message) + const res = await getMessaging().sendEachForMulticast(message) logger.info('send notification result: ', res.responses) return res @@ -75,7 +75,7 @@ export const sendBatchPushNotifications = async ( messages: Message[] ): Promise => { try { - const res = await getMessaging().sendAll(messages) + const res = await getMessaging().sendEach(messages) logger.info(`success count: ${res.successCount}`) return res diff --git a/packages/api/test/global-setup.ts b/packages/api/test/global-setup.ts index dce893a86..31f9a3d86 100644 --- a/packages/api/test/global-setup.ts +++ b/packages/api/test/global-setup.ts @@ -7,7 +7,7 @@ export const mochaGlobalSetup = async () => { await createTestConnection() console.log('db connection created') - if (env.redis.url) { + if (env.redis.cache.url) { await redisDataSource.initialize() console.log('redis connection created') } diff --git a/packages/api/test/global-teardown.ts b/packages/api/test/global-teardown.ts index d76129414..2e476c55e 100644 --- a/packages/api/test/global-teardown.ts +++ b/packages/api/test/global-teardown.ts @@ -10,7 +10,7 @@ export const mochaGlobalTeardown = async () => { await appDataSource.destroy() console.log('db connection closed') - if (env.redis.url) { + if (env.redis.cache.url) { await redisDataSource.shutdown() console.log('redis connection closed') } diff --git a/packages/api/test/resolvers/article.test.ts b/packages/api/test/resolvers/article.test.ts index 601b2a498..c25d1447f 100644 --- a/packages/api/test/resolvers/article.test.ts +++ b/packages/api/test/resolvers/article.test.ts @@ -218,14 +218,18 @@ const savePageQuery = ( ` } -const saveFileQuery = (url: string, uploadFileId: string) => { +const saveFileQuery = ( + clientRequestId: string, + url: string, + uploadFileId: string +) => { return ` mutation { saveFile ( input: { url: "${url}", source: "test", - clientRequestId: "${generateFakeUuid()}", + clientRequestId: "${clientRequestId}", uploadFileId: "${uploadFileId}", } ) { @@ -832,8 +836,23 @@ describe('Article API', () => { let query = '' let url = '' let uploadFileId = '' + let itemId = '' + + before(async () => { + const item = await createLibraryItem( + { + user: { id: user.id }, + originalUrl: 'https://blog.omnivore.app/setBookmarkArticle', + slug: 'test-with-omnivore', + readableContent: '

test

', + title: 'test title', + readingProgressBottomPercent: 100, + readingProgressTopPercent: 80, + }, + user.id + ) + itemId = item.id - before(() => { sinon.replace( uploads, 'getStorageFileDetails', @@ -842,7 +861,7 @@ describe('Article API', () => { }) beforeEach(() => { - query = saveFileQuery(url, uploadFileId) + query = saveFileQuery(itemId, url, uploadFileId) }) after(() => { diff --git a/packages/content-fetch/src/redis_data_source.ts b/packages/content-fetch/src/redis_data_source.ts index 1a95f9d6e..aa985348a 100644 --- a/packages/content-fetch/src/redis_data_source.ts +++ b/packages/content-fetch/src/redis_data_source.ts @@ -1,8 +1,12 @@ import Redis, { RedisOptions } from 'ioredis' +type RedisClientType = 'cache' | 'mq' +type RedisDataSourceOption = { + url?: string + cert?: string +} export type RedisDataSourceOptions = { - REDIS_URL?: string - REDIS_CERT?: string + [key in RedisClientType]: RedisDataSourceOption } export class RedisDataSource { @@ -14,12 +18,12 @@ export class RedisDataSource { constructor(options: RedisDataSourceOptions) { this.options = options - this.cacheClient = createRedisClient('cache', this.options) - this.queueRedisClient = createRedisClient('queue', this.options) - } + const cacheClient = createIORedisClient('cache', this.options) + if (!cacheClient) throw 'Error initializing cache redis client' - setOptions(options: RedisDataSourceOptions): void { - this.options = options + this.cacheClient = cacheClient + this.queueRedisClient = + createIORedisClient('mq', this.options) || this.cacheClient // if mq is not defined, use cache } async shutdown(): Promise { @@ -32,46 +36,45 @@ export class RedisDataSource { } } -const createRedisClient = (name: string, options: RedisDataSourceOptions) => { - const redisURL = options.REDIS_URL - const cert = options.REDIS_CERT?.replace(/\\n/g, '\n') // replace \n with new line +const createIORedisClient = ( + name: RedisClientType, + options: RedisDataSourceOptions +): Redis | undefined => { + const option = options[name] + const redisURL = option.url if (!redisURL) { - throw 'Error: no redisURL supplied' + console.log(`no redisURL supplied: ${name}`) + return undefined } - const redisOptions: RedisOptions = { - name, - connectTimeout: 10000, // 10 seconds - tls: cert + const redisCert = option.cert + const tls = + redisURL.startsWith('rediss://') && redisCert ? { - cert, - rejectUnauthorized: false, // for self-signed certs + ca: redisCert, + rejectUnauthorized: false, } - : undefined, + : undefined + + const redisOptions: RedisOptions = { + tls, + name, + connectTimeout: 10000, maxRetriesPerRequest: null, offlineQueue: false, } - - const redis = new Redis(redisURL, redisOptions) - - redis.on('connect', () => { - console.log('Redis connected', name) - }) - - redis.on('error', (err) => { - console.error('Redis error', err, name) - }) - - redis.on('close', () => { - console.log('Redis closed', name) - }) - - return redis + return new Redis(redisURL, redisOptions) } export const redisDataSource = new RedisDataSource({ - REDIS_URL: process.env.REDIS_URL, - REDIS_CERT: process.env.REDIS_CERT, + cache: { + url: process.env.REDIS_URL, + cert: process.env.REDIS_CERT, + }, + mq: { + url: process.env.MQ_REDIS_URL, + cert: process.env.MQ_REDIS_CERT, + }, }) // eslint-disable-next-line @typescript-eslint/no-misused-promises diff --git a/packages/content-fetch/src/request_handler.ts b/packages/content-fetch/src/request_handler.ts index 0106d8058..5fb1d0066 100644 --- a/packages/content-fetch/src/request_handler.ts +++ b/packages/content-fetch/src/request_handler.ts @@ -50,12 +50,11 @@ interface FetchResult { title?: string content?: string contentType?: string - readabilityResult?: unknown } export const cacheFetchResult = async (fetchResult: FetchResult) => { - // cache the fetch result for 4 hours - const ttl = 4 * 60 * 60 + // cache the fetch result for 24 hours + const ttl = 24 * 60 * 60 const key = `fetch-result:${fetchResult.finalUrl}` const value = JSON.stringify(fetchResult) return redisDataSource.cacheClient.set(key, value, 'EX', ttl, 'NX') @@ -69,7 +68,6 @@ export const contentFetchRequestHandler: RequestHandler = async (req, res) => { // users is used when saving article for multiple users let users = body.users || [] const userId = body.userId - const folder = body.folder // userId is used when saving article for a single user if (userId) { users = [ @@ -105,7 +103,6 @@ export const contentFetchRequestHandler: RequestHandler = async (req, res) => { rssFeedUrl, savedAt, publishedAt, - folder, users, } diff --git a/packages/content-handler/src/redis.ts b/packages/content-handler/src/redis.ts index e6e657e2b..5bc90decc 100644 --- a/packages/content-handler/src/redis.ts +++ b/packages/content-handler/src/redis.ts @@ -5,7 +5,7 @@ export const createRedisClient = (url?: string, cert?: string) => { connectTimeout: 10000, // 10 seconds tls: cert ? { - cert, + cert: cert.replace(/\\n/g, '\n'), // replace \n with new line rejectUnauthorized: false, // for self-signed certs } : undefined, diff --git a/packages/content-handler/src/websites/nitter-handler.ts b/packages/content-handler/src/websites/nitter-handler.ts index 36ebfd8c2..f8d927d6f 100644 --- a/packages/content-handler/src/websites/nitter-handler.ts +++ b/packages/content-handler/src/websites/nitter-handler.ts @@ -31,7 +31,7 @@ interface Tweet { export class NitterHandler extends ContentHandler { // matches twitter.com and nitter.net urls URL_MATCH = - /((twitter\.com)|(nitter\.net))\/(?:#!\/)?(\w+)\/status(?:es)?\/(\d+)(?:\/.*)?/ + /((x\.com)|(twitter\.com)|(nitter\.net))\/(?:#!\/)?(\w+)\/status(?:es)?\/(\d+)(?:\/.*)?/ INSTANCES = [ { value: 'https://nitter.moomoo.me', score: 0 }, { value: 'https://nitter.net', score: 1 }, // the official instance @@ -316,7 +316,7 @@ export class NitterHandler extends ContentHandler { parseTweetUrl = (url: string) => { const match = url.match(this.URL_MATCH) return { - domain: match?.[1], + domain: match?.[1]?.replace('x', 'twitter'), username: match?.[4], tweetId: match?.[5], } diff --git a/packages/db/migrations/0159.do.alter_subscriptions.sql b/packages/db/migrations/0159.do.alter_subscriptions.sql new file mode 100755 index 000000000..e4050eec5 --- /dev/null +++ b/packages/db/migrations/0159.do.alter_subscriptions.sql @@ -0,0 +1,17 @@ +-- Type: DO +-- Name: alter_subscriptions +-- Description: Alter omnivore.subscriptions table to add a new state and date column + +BEGIN; + +ALTER TABLE omnivore.subscriptions + ADD COLUMN failed_at timestamptz, + ADD COLUMN refreshed_at timestamptz; +UPDATE omnivore.subscriptions + SET refreshed_at = last_fetched_at + WHERE last_fetched_at IS NOT NULL; + +ALTER TABLE omnivore.subscriptions + RENAME COLUMN last_fetched_at TO most_recent_item_date; + +COMMIT; diff --git a/packages/db/migrations/0159.undo.alter_subscriptions.sql b/packages/db/migrations/0159.undo.alter_subscriptions.sql new file mode 100755 index 000000000..6c9f8c3ca --- /dev/null +++ b/packages/db/migrations/0159.undo.alter_subscriptions.sql @@ -0,0 +1,14 @@ +-- Type: UNDO +-- Name: alter_subscriptions +-- Description: Alter omnivore.subscriptions table to add a new state and date column + +BEGIN; + +ALTER TABLE omnivore.subscriptions + RENAME COLUMN most_recent_item_date TO last_fetched_at; + +ALTER TABLE omnivore.subscriptions + DROP COLUMN failed_at, + DROP COLUMN refreshed_at; + +COMMIT; diff --git a/packages/inbound-email-handler/src/index.ts b/packages/inbound-email-handler/src/index.ts index d6874d866..eefadb6a3 100644 --- a/packages/inbound-email-handler/src/index.ts +++ b/packages/inbound-email-handler/src/index.ts @@ -117,8 +117,6 @@ export const inboundEmailHandler = Sentry.GCPFunction.wrapHttpFunction( } } const headers = parseHeaders(parsed.headers) - console.log('parsed: ', parsed) - console.log('headers: ', headers) // original sender email address const from = parsed['from'] diff --git a/packages/puppeteer-parse/src/index.ts b/packages/puppeteer-parse/src/index.ts index 2629689c2..a02a3595b 100644 --- a/packages/puppeteer-parse/src/index.ts +++ b/packages/puppeteer-parse/src/index.ts @@ -1,10 +1,7 @@ /* eslint-disable @typescript-eslint/no-unsafe-member-access */ /* eslint-disable @typescript-eslint/no-unsafe-assignment */ -import { preHandleContent, preParseContent } from '@omnivore/content-handler' -import { Readability } from '@omnivore/readability' +import { preHandleContent } from '@omnivore/content-handler' import axios from 'axios' -import crypto from 'crypto' -import createDOMPurify, { SanitizeElementHookEvent } from 'dompurify' // const { Storage } = require('@google-cloud/storage'); import { parseHTML } from 'linkedom' import path from 'path' @@ -13,7 +10,6 @@ import puppeteer from 'puppeteer-extra' import AdblockerPlugin from 'puppeteer-extra-plugin-adblocker' import StealthPlugin from 'puppeteer-extra-plugin-stealth' import Url from 'url' -import { encode } from 'urlsafe-base64' // Add stealth plugin to hide puppeteer usage puppeteer.use(StealthPlugin()) @@ -28,12 +24,12 @@ puppeteer.use(AdblockerPlugin({ blockTrackers: true })) // const filePath = `${os.tmpdir()}/previewImage.png` -const MOBILE_USER_AGENT = - 'Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.62 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)' +// const MOBILE_USER_AGENT = +// 'Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.62 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)' const DESKTOP_USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11_6_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4372.0 Safari/537.36' -const BOT_DESKTOP_USER_AGENT = - 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11_6_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4372.0 Safari/537.36' +// const BOT_DESKTOP_USER_AGENT = +// 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11_6_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4372.0 Safari/537.36' const NON_BOT_DESKTOP_USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11_6_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4372.0 Safari/537.36' const NON_BOT_HOSTS = ['bloomberg.com', 'forbes.com'] @@ -156,8 +152,8 @@ export const fetchContent = async ( page: Page | undefined, title: string | undefined, content: string | undefined, - contentType: string | undefined, - readabilityResult: Readability.ParseResult | null | undefined + contentType: string | undefined + try { url = getUrl(url) if (!url) { @@ -230,34 +226,26 @@ export const fetchContent = async ( console.info('fallback to scrapingbee', url) const sbResult = await fetchContentWithScrapingBee(url) - content = sbResult.domContent - title = sbResult.title - } else { - throw e + + return { + finalUrl: url, + title: sbResult.title, + content: sbResult.domContent, + contentType, + } } + + throw e } finally { // close browser context if it was opened if (context) { await context.close() } - // save non pdf content - if (url && contentType !== 'application/pdf') { - // parse content if it is not empty - if (content) { - let document = parseHTML(content).document - // preParse content - const preParsedDom = await preParseContent(url, document) - if (preParsedDom) { - document = preParsedDom - } - readabilityResult = await getReadabilityResult(url, document) - } - } console.info(`content-fetch result`, logRecord) } - return { finalUrl: url, title, content, readabilityResult, contentType } + return { finalUrl: url, title, content, contentType } } function validateUrlString(url: string) { @@ -741,99 +729,3 @@ async function retrieveHtml(page: Page, logRecord: Record) { // console.info(`preview-image`, logRecord); // return res.redirect(`${process.env.PREVIEW_IMAGE_CDN_ORIGIN}/${destination}`); // } - -const DOM_PURIFY_CONFIG = { - ADD_TAGS: ['iframe'], - ADD_ATTR: ['allow', 'allowfullscreen', 'frameborder', 'scrolling'], - FORBID_ATTR: [ - 'data-ml-dynamic', - 'data-ml-dynamic-type', - 'data-orig-url', - 'data-ml-id', - 'data-ml', - 'data-xid', - 'data-feature', - ], -} - -function domPurifySanitizeHook(node: Element, data: SanitizeElementHookEvent) { - if (data.tagName === 'iframe') { - const urlRegex = /^(https?:)?\/\/www\.youtube(-nocookie)?\.com\/embed\//i - const src = node.getAttribute('src') || '' - const dataSrc = node.getAttribute('data-src') || '' - - if (src && urlRegex.test(src)) { - return - } - - if (dataSrc && urlRegex.test(dataSrc)) { - node.setAttribute('src', dataSrc) - return - } - - node.parentNode?.removeChild(node) - } -} - -function getPurifiedContent(html: Document) { - const newWindow = parseHTML('') - const DOMPurify = createDOMPurify(newWindow) - DOMPurify.addHook('uponSanitizeElement', domPurifySanitizeHook) - const clean = DOMPurify.sanitize(html, DOM_PURIFY_CONFIG) - return parseHTML(clean).document -} - -function signImageProxyUrl(url: string) { - return encode( - crypto - .createHmac('sha256', process.env.IMAGE_PROXY_SECRET || '') - .update(url) - .digest() - ) -} - -function createImageProxyUrl(url: string, width = 0, height = 0) { - if (!process.env.IMAGE_PROXY_URL || !process.env.IMAGE_PROXY_SECRET) { - return url - } - - const urlWithOptions = `${url}#${width}x${height}` - const signature = signImageProxyUrl(urlWithOptions) - - return `${process.env.IMAGE_PROXY_URL}/${width}x${height},s${signature}/${url}` -} - -async function getReadabilityResult(url: string, document: Document) { - // First attempt to read the article as is. - // if that fails attempt to purify then read - const sources = [ - () => { - return document - }, - () => { - return getPurifiedContent(document) - }, - ] - - for (const source of sources) { - const document = source() - if (!document) { - continue - } - - try { - const article = await new Readability(document, { - createImageProxyUrl, - url, - }).parse() - - if (article) { - return article - } - } catch (error) { - console.log('parsing error for url', url, error) - } - } - - return null -} diff --git a/packages/readabilityjs/Readability.js b/packages/readabilityjs/Readability.js index 375b3a6ee..2a6aced84 100644 --- a/packages/readabilityjs/Readability.js +++ b/packages/readabilityjs/Readability.js @@ -206,7 +206,7 @@ Readability.prototype = { unlikelyCandidates: /\bad\b|ai2html|banner|breadcrumbs|breadcrumb|combx|comment|community|cover-wrap|disqus|extra|footer|gdpr|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager(?!ow)|popup|yom-remote|copyright|keywords|outline|infinite-list|beta|recirculation|site-index|hide-for-print|post-end-share-cta|post-end-cta-full|post-footer|post-head|post-tag|li-date|main-navigation|programtic-ads|outstream_article|hfeed|comment-holder|back-to-top|show-up-next|onward-journey|topic-tracker|list-nav|block-ad-entity|adSpecs|gift-article-button|modal-title|in-story-masthead|share-tools|standard-dock|expanded-dock|margins-h|subscribe-dialog|icon|bumped|dvz-social-media-buttons|post-toc|mobile-menu|mobile-navbar|tl_article_header|mvp(-post)*-(add-story|soc(-mob)*-wrap)|w-condition-invisible|rich-text-block main w-richtext|rich-text-block_ataglance at-a-glance test w-richtext|PostsPage-commentsSection|hide-text/i, // okMaybeItsACandidate: /and|article(?!-breadcrumb)|body|column|content|main|shadow|post-header/i, get okMaybeItsACandidate() { - return new RegExp(`and|(? 0) { code = languages[0].code; } - console.log('Getting language name from code: ', code); + this.log('Getting language name from code: ', code); let lang = new Intl.DisplayNames(['en'], {type: 'language'}); return lang.of(code); } catch (error) { - console.error('Failed to get language', error); + this.log('Failed to get language', error); return 'English'; } }, @@ -3135,6 +3135,7 @@ Readability.prototype = { previewImage: metadata.previewImage, publishedDate, language, + documentElement: articleContent, }; } }; diff --git a/packages/readabilityjs/test/index.html b/packages/readabilityjs/test/index.html index 3b0a9e2c8..cfa8c53ef 100644 --- a/packages/readabilityjs/test/index.html +++ b/packages/readabilityjs/test/index.html @@ -80,6 +80,12 @@ [dom-distiller] +
  • realpython
    + [source] + [readability] + [dom-distiller] +
    • +
  • josephg
    [source] [readability] diff --git a/packages/readabilityjs/test/test-pages/realpython/distiller.html b/packages/readabilityjs/test/test-pages/realpython/distiller.html new file mode 100644 index 000000000..1c34bc3f0 --- /dev/null +++ b/packages/readabilityjs/test/test-pages/realpython/distiller.html @@ -0,0 +1,932 @@ +
    Python 3.10: Cool New Features for You to Try

    + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    + Python 3.10 is out! Volunteers have been working on the new version since May 2020 to bring you a better, faster, and more secure Python. As of October 4, 2021, the first official version is available. +

    + Each new version of Python brings a host of changes. You can read about all of them in the documentation. Here, you’ll get to learn about the coolest new features. +

    + In this tutorial, you’ll learn about: +

    • Debugging with more helpful and precise error messages
    • Using structural pattern matching to work with data structures
    • Adding more readable and more specific type hints
    • Checking the length of sequences when using zip()
    • Calculating multivariable statistics

    + To try out the new features yourself, you need to run Python 3.10. You can get it from the Python homepage. Alternatively, you can use Docker with the latest Python image. +

    + Better Error Messages +

    + Python is often lauded for being a user-friendly programming language. While this is true, there are certain parts of Python that could be friendlier. Python 3.10 comes with a host of more precise and constructive error messages. In this section, you’ll see some of the newest improvements. The full list is available in the documentation. +

    + Think back to writing your first Hello World program in Python: +

    + Python + +

    + Maybe you created a file, added the famous call to print(), and saved it as hello.py. You then ran the program, eager to call yourself a proper Pythonista. However, something went wrong: +

    + Shell +

    + There was a SyntaxError in the code. EOL, what does that even mean? You went back to your code, and after a bit of staring and searching, you realized that there was a missing quotation mark at the end of your string. +

    + One of the more impactful improvements in Python 3.10 is better and more precise error messages for many common issues. If you run your buggy Hello World in Python 3.10, you’ll get a bit more help than in earlier versions of Python: +

    + Shell +

    + The error message is still a bit technical, but gone is the mysterious EOL. Instead, the message tells you that you need to terminate your string! There are similar improvements to many different error messages, as you’ll see below. +

    + A SyntaxError is an error raised when your code is parsed, before it even starts to execute. Syntax errors can be tricky to debug because the interpreter provides imprecise or sometimes even misleading error messages. The following code is missing a curly brace to terminate the dictionary: +

    + Python + +

    + The missing closing curly brace that should have been on line 7 is an error. If you run this code with Python 3.9 or earlier, you’ll see the following error message: +

    + Python Traceback + +

    + The error message highlights line 8, but there are no syntactical problems in line 8! If you’ve experienced your share of syntax errors in Python, you might already know that the trick is to look at the lines before the one Python complains about. In this case, you’re looking for the missing closing brace on line 7. +

    + In Python 3.10, the same code shows a much more helpful and precise error message: +

    + Python Traceback + +

    + This points you straight to the offending dictionary and allows you to fix the issue in no time. +

    + There are a few other ways to mess up dictionary syntax. A typical one is forgetting a comma after one of the items: +

    + Python + +

    + In this code, a comma is missing at the end of line 4. Python 3.10 gives you a clear suggestion on how to fix your code: +

    + Python Traceback + +

    + You can add the missing comma and have your code back up and running in no time. +

    + Another common mistake is using the assignment operator (=) instead of the equality comparison operator (==) when you’re comparing values. Previously, this would just cause another invalid syntax message. In the newest version of Python, you get some more advice: +

    + Python +

    + The parser suggests that you maybe meant to use a comparison operator or an assignment expression operator instead. +

    + Take note of another nifty improvement in Python 3.10 error messages. The last two examples show how carets (^^^) highlight the whole offending expression. Previously, a single caret symbol (^) indicated just an approximate location. +

    + The final error message improvement that you’ll play with for now is that attribute and name errors can now offer suggestions if you misspell an attribute or a name: +

    + Python +

    + Note that the suggestions work for both built-in names and names that you define yourself, although they may not be available in all environments. If you like these kinds of suggestions, check out BetterErrorMessages, which offers similar suggestions in even more contexts. +

    + The improvements you’ve seen in this section are just some of the many error messages that have gotten a face-lift. The new Python will be even more user-friendly than before, and hopefully, the new error messages will save you both time and frustration going forward. +

    + Structural Pattern Matching +

    + The biggest new feature in Python 3.10, probably both in terms of controversy and potential impact, is structural pattern matching. Its introduction has sometimes been referred to as switch ... case coming to Python, but you’ll see that structural pattern matching is much more powerful than that. +

    + You’ll see three different examples that together highlight why this feature is called structural pattern matching and show you how you can use this new feature: +

    1. Detecting and deconstructing different structures in your data
    2. Using different kinds of patterns
    3. Matching literal patterns

    + Structural pattern matching is a comprehensive addition to the Python language. To give you a taste of how you can take advantage of it in your own projects, the next three subsections will dive into some of the details. You’ll also see some links that can help you explore in even more depth if you want. +

    + Deconstructing Data Structures +

    + At its core, structural pattern matching is about defining patterns to which your data structures can be matched. In this section, you’ll study a practical example where you’ll work with data that are structured differently, even though the meaning is the same. You’ll define several patterns, and depending on which pattern matches your data, you’ll process your data appropriately. +

    + This section will be a bit light on explanations of the possible patterns. Instead, it will try to give you an impression of the possibilities. The next section will step back and explain the patterns in more detail. +

    + Time to match your first pattern! The following example uses a match ... case block to find the first name of a user by extracting it from a user data structure: +

    + Python +

    + You can see structural pattern matching at work in the highlighted lines. user is a small dictionary with user information. The case line specifies a pattern that user is matched against. In this case, you’re looking for a dictionary with a "name" key whose value is a new dictionary. This nested dictionary has a key called "first". The corresponding value is bound to the variable first_name. +

    + For a practical example, say that you’re processing user data where the underlying data model changes over time. Therefore, you need to be able to process different versions of the same data. +

    + In the next example, you’ll use data from randomuser.me. This is a great API for generating random user data that you can use during testing and development. The API is also an example of an API that has changed over time. You can still access the old versions of the API. +

    + You may expand the collapsed section below to see how you can use requests to obtain different versions of the user data using the API: +

    + You can get a random user from the API using requests as follows: +

    + Python + +

    + get_user() gets one random user in JSON format. Note the version parameter. The structure of the returned data has changed quite a bit between earlier versions like "1.1" and the current version "1.3", but in each case, the actual user data are contained in a list inside the "results" array. The function returns the first—and only—user in this list. +

    + At the time of writing, the latest version of the API is 1.3 and the data has the following structure: +

    + JSON + +

    + One of the members that changed between different versions is "dob", the date of birth. Note that in version 1.3, this is a JSON object with two members, "date" and "age". +

    + Compare the result above with a version 1.1 random user: +

    + JSON + +

    + Observe that in this older format, the value of the "dob" member is a plain string. +

    + In this example, you’ll work with the information about the date of birth (dob) for each user. The structure of these data has changed between different versions of the Random User API: +

    + JSON + +

    + Note that in version 1.1, the date of birth is represented as a simple string, while in version 1.3, it’s a JSON object with two members: "date" and "age". Say that you want to find the age of a user. Depending on the structure of your data, you’d either need to calculate the age based on the date of birth or look up the age if it’s already available. +

    + Traditionally, you would detect the structure of the data with an if test, maybe based on the type of the "dob" field. You can approach this differently in Python 3.10. Now, you can use structural pattern matching instead: +

    + Python + +

    + The match ... case construct is new in Python 3.10 and is how you perform structural pattern matching. You start with a match statement that specifies what you want to match. In this example, that’s the user data structure. +

    + One or several case statements follow match. Each case describes one pattern, and the indented block beneath it says what should happen if there’s a match. In this example: +

    • + Line 8 matches a dictionary with a "dob" key whose value is another dictionary with an integer (int) item named "age". The name age captures its value. +

    • + Line 10 matches any dictionary with a "dob" key. The name dob captures its value. +

    + One important feature of pattern matching is that at most one pattern will be matched. Since the pattern on line 10 matches any dictionary with "dob", it’s important that the more specific pattern on line 8 comes first. +

    + Before looking closer at the details of the patterns and how they work, try calling get_age() with different data structures to see the result: +

    + Python +

    + Your code can calculate the age correctly for both versions of the user data, which have different dates of birth. +

    + Look closer at those patterns. The first pattern, {"dob": {"age": int(age)}}, matches version 1.3 of the user data: +

    + Python + +

    + The first pattern is a nested pattern. The outer curly braces say that a dictionary with the key "dob" is required. The corresponding value should be a dictionary. This nested dictionary must match the subpattern {"age": int(age)}. In other words, it needs to have an "age" key with an integer value. That value is bound to the name age. +

    + The second pattern, {"dob": dob}, matches the older version 1.1 of the user data: +

    + Python + +

    + This second pattern is a simpler pattern than the first one. Again, the curly braces indicate that it will match a dictionary. However, any dictionary with a "dob" key is matched because there are no other restrictions specified. The value of that key is bound to the name dob. +

    + The main takeaway is that you can describe the structure of your data using mostly familiar notation. One striking change, though, is that you can use names like dob and age, which aren’t yet defined. Instead, values from your data are bound to these names when a pattern matches. +

    + You’ve explored some of the power of structural pattern matching in this example. In the next section, you’ll dive a bit more into the details. +

    + These documents give you a lot of background and detail if you’re interested in a deeper dive than what follows. +

    + Patterns are at the center of structural pattern matching. In this section, you’ll learn about some of the different kinds of patterns that exist: +

    • Mapping patterns match mapping structures like dictionaries.
    • Sequence patterns match sequence structures like tuples and lists.
    • Capture patterns bind values to names.
    • AS patterns bind the value of subpatterns to names.
    • OR patterns match one of several different subpatterns.
    • Wildcard patterns match anything.
    • Class patterns match class structures.
    • Value patterns match values stored in attributes.
    • Literal patterns match literal values.

    + You already used several of them in the example in the previous section. In particular, you used mapping patterns to unravel data stored in dictionaries. In this section, you’ll learn more about how some of these work. All the details are available in the PEPs mentioned above. +

    + A capture pattern is used to capture a match to a pattern and bind it to a name. Consider the following recursive function that sums a list of numbers: +

    + Python + +

    + The first case on line 3 matches the empty list and returns 0 as its sum. The second case on line 5 uses a sequence pattern with two capture patterns to match lists with one or more elements. The first element in the list is captured and bound to the name first. The second capture pattern, *rest, uses unpacking syntax to match any number of elements. rest will bind to a list containing all elements of numbers except the first one. +

    + sum_list() calculates the sum of a list of numbers by recursively adding the first number in the list and the sum of the rest of the numbers. You can use it as follows: +

    + Python +

    + The sum of 4 + 5 + 9 + 4 is correctly calculated to be 22. As an exercise for yourself, you can try to trace the recursive calls to sum_list() to make sure you understand how the code sums the whole list. +

    + sum_list() handles summing up a list of numbers. Observe what happens if you try to sum anything that isn’t a list: +

    + Python +

    + Passing a string or a number to sum_list() returns None. This occurs because none of the patterns match, and the execution continues after the match block. That happens to be the end of the function, so sum_list() implicitly returns None. +

    + Often, though, you want to be alerted about failed matches. You can add a catchall pattern as the final case that handles this by raising an error, for example. You can use the underscore (_) as a wildcard pattern that matches anything without binding it to a name. You can add some error handling to sum_list() as follows: +

    + Python + +

    + The final case will match anything that doesn’t match the first two patterns. This will raise a descriptive error, for instance, if you try to calculate sum_list(4594). This is useful when you need to alert your users that some input was not matched as expected. +

    + Your patterns are still not foolproof, though. Consider what happens if you try to sum a list of strings: +

    + Python +

    + The base case returns 0, so therefore the summing only works for types that you can add with numbers. Python doesn’t know how to add numbers and text strings together. You can restrict your pattern to only match integers using a class pattern: +

    + Python + +

    + Adding int() around first makes sure that the pattern only matches if the value is an integer. This might be too restrictive, though. Your function should be able to sum both integers and floating-point numbers, so how can you allow this in your pattern? +

    + To check whether at least one out of several subpatterns match, you can use an OR pattern. OR patterns consist of two or more subpatterns, and the pattern matches if at least one of the subpatterns does. You can use this to match when the first element is either of type int or type float: +

    + Python + +

    + You use the pipe symbol (|) to separate the subpatterns in an OR pattern. Your function now allows summing a list of floating-point numbers: +

    + Python +

    + There’s a lot of power and flexibility within structural pattern matching, even more than what you’ve seen so far. Some things that aren’t covered in this overview are: +

    + If you’re interested, have a look in the documentation to learn more about these features as well. In the next section, you’ll learn about literal patterns and value patterns. +

    + Matching Literal Patterns +

    + A literal pattern is a pattern that matches a literal object like an explicit string or number. In a sense, this is the most basic kind of pattern and allows you to emulate switch ... case statements seen in other languages. The following example matches a specific name: +

    + Python + +

    + The first case matches the literal string "Guido". In this case, you use _ as a wildcard to print a generic greeting whenever name is not "Guido". Such literal patterns can sometimes take the place of if ... elif ... else constructs and can play the same role that switch ... case does in some other languages. +

    + One limitation with structural pattern matching is that you can’t directly match values stored in variables. Say that you’ve defined bdfl = "Guido". A pattern like case bdfl: will not match "Guido". Instead, this will be interpreted as a capture pattern that matches anything and binds that value to bdfl, effectively overwriting the old value. +

    + You can, however, use a value pattern to match stored values. A value pattern looks a bit like a capture pattern but uses a previously defined dotted name that holds the value that will be matched against. +

    + You can, for example, use an enumeration to create such dotted names: +

    + Python + +

    + The first case now uses a value pattern to match Pythonista.BDFL, which is "Guido". Note that you can use any dotted name in a value pattern. You could, for example, have used a regular class or a module instead of the enumeration. +

    + To see a bigger example of how to use literal patterns, consider the game of FizzBuzz. This is a counting game where you should replace some numbers with words according to the following rules: +

    • You replace numbers divisible by 3 with fizz.
    • You replace numbers divisible by 5 with buzz.
    • You replace numbers divisible by both 3 and 5 with fizzbuzz.

    + FizzBuzz is sometimes used to introduce conditionals in programming education and as a screening problem in interviews. Even though a solution is quite straightforward, Joel Grus has written a full book about different ways to program the game. +

    + A typical solution in Python will use if ... elif ... else as follows: +

    + Python + +

    + The % operator calculates the modulus, which you can use to test divisibility. Namely, if a modulus b is 0 for two numbers a and b, then a is divisible by b. +

    + In fizzbuzz(), you calculate number % 3 and number % 5, which you then use to test for divisibility with 3 and 5. Note that you must do the test for divisibility with both 3 and 5 first. If not, numbers that are divisible by both 3 and 5 will be covered by either the "fizz" or the "buzz" cases instead. +

    + You can check that your implementation gives the expected result: +

    + Python +

    + You can confirm for yourself that 3 is divisible by 3, 65 is divisible by 5, and 15 is divisible by both 3 and 5, while 14 and 92 aren’t divisible by either 3 or 5. +

    + An if ... elif ... else structure where you’re comparing one or a few variables several times over is quite straightforward to rewrite using pattern matching instead. For example, you can do the following: +

    + Python + +

    + You match on both mod_3 and mod_5. Each case pattern then matches either the literal number 0 or the wildcard _ on the corresponding values. +

    + Compare and contrast this version with the previous one. Note how the pattern (0, 0) corresponds to the test mod_3 == 0 and mod_5 == 0, while (0, _) corresponds to mod_3 == 0. +

    + As you saw earlier, you can use an OR pattern to match on several different patterns. For example, since mod_3 can only take the values 0, 1, and 2, you can replace case (_, 0) with case (1, 0) | (2, 0). Remember that (0, 0) has already been covered. +

    + The Python core developers have consciously chosen not to include switch ... case statements in the language earlier. However, there are some third-party packages that do, like switchlang, which adds a switch command that also works on earlier versions of Python. +

    + Type Unions, Aliases, and Guards +

    + Reliably, each new Python release brings some improvements to the static typing system. Python 3.10 is no exception. In fact, four different PEPs about typing accompany this new release: +

    + PEP 604 will probably be the most widely used of these changes going forward, but you’ll get a brief overview of each of the features in this section. +

    + You can use union types to declare that a variable can have one of several different types. For example, you’ve been able to type hint a function calculating the mean of a list of numbers, floats, or integers as follows: +

    + Python + +

    + The annotation List[Union[float, int]] means that numbers should be a list where each element is either a floating-point number or an integer. This works well, but the notation is a bit verbose. Also, you need to import both List and Union from typing. +

    + In Python 3.10, you can replace Union[float, int] with the more succinct float | int. Combine this with the ability to use list instead of typing.List in type hints, which Python 3.9 introduced. You can then simplify your code while keeping all the type information: +

    + Python + +

    + The annotation of numbers is easier to read now, and as an added bonus, you didn’t need to import anything from typing. +

    + A special case of union types is when a variable can have either a specific type or be None. You can annotate such optional types either as Union[None, T] or, equivalently, Optional[T] for some type T. There is no new, special syntax for optional types, but you can use the new union syntax to avoid importing typing.Optional: +

    + Python + +

    + In this example, address is allowed to be either None or a string. +

    + You can also use the new union syntax at runtime in isinstance() or issubclass() tests: +

    + Python +

    + Traditionally, you’ve used tuples to test for several types at once—for example, (str, int) instead of str | int. This old syntax will still work. +

    + Type aliases allow you to quickly define new aliases that can stand in for more complicated type declarations. For example, say that you’re representing a playing card using a tuple of suit and rank strings and a deck of cards by a list of such playing card tuples. A deck of cards is then type hinted as list[tuple[str, str]]. +

    + To simplify type annotation, you define type aliases as follows: +

    + Python + +

    + This usually works okay. However, it’s often not possible for the type checker to know whether such a statement is a type alias or just the definition of a regular global variable. To help the type checker—or really, help the type checker help you—you can now explicitly annotate type aliases: +

    + Python + +

    + Adding the TypeAlias annotation clarifies the intention, both to a type checker and to anyone reading your code. +

    + Type guards are used to narrow down union types. The following function takes in either a string or None but always returns a tuple of strings representing a playing card: +

    + Python + +

    + The highlighted line works as a type guard, and static type checkers are able to realize that suit is necessarily a string when it’s returned. +

    + Currently, the type checkers can only use a few different constructs to narrow down union types in this way. With the new typing.TypeGuard, you can annotate custom functions that can be used to narrow down union types: +

    + Python + +

    + is_deck_of_cards() should return True or False depending on whether obj represents a Deck object or not. You can then use your guard function, and the type checker will be able to narrow down the types correctly: +

    + Python + +

    + Inside of the if block, the type checker knows that card_or_deck is, in fact, of the type Deck. See PEP 647 for more details. +

    + The final new typing feature is Parameter Specification Variables, which is related to type variables. Consider the definition of a decorator. In general, it looks something like the following: +

    + Python + +

    + The annotations mean that the function returned by the decorator is a callable with some parameters and the same return type, R, as the function passed into the decorator. The ellipsis (...) in the function header correctly allows any number of parameters, and each of those parameters can be of any type. However, there’s no validation that the returned callable has the same parameters as the function that was passed in. In practice, this means that type checkers aren’t able to check decorated functions properly. +

    + Unfortunately, you can’t use TypeVar for the parameters because you don’t know how many parameters the function will have. In Python 3.10, you’ll have access to ParamSpec in order to type hint these kinds of callables properly. ParamSpec works similarly to TypeVar but stands in for several parameters at once. You can rewrite your decorator as follows to take advantage of ParamSpec: +

    + Python + +

    + Note that you also use P when you annotate wrapper(). You can also use the new typing.Concatenate to add types to ParamSpec. See the documentation and PEP 612 for details and examples. +

    + Stricter Zipping of Sequences +

    + zip() is a built-in function in Python that can combine elements from several sequences. Python 3.10 introduces the new strict parameter, which adds a runtime test to check that all sequences being zipped have the same length. +

    + As an example, consider the following table of Lego sets: +

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Name + + Set Number + + Pieces +
    + Louvre + + 21024 + + 695 +
    + Diagon Alley + + 75978 + + 5544 +
    + NASA Apollo Saturn V + + 92176 + + 1969 +
    + Millennium Falcon + + 75192 + + 7541 +
    + New York City + + 21028 + + 598 +

    + One way to represent these data in plain Python would be with each column as a list. It could look something like this: +

    + Python +

    + Note that you have three independent lists, but there’s an implicit correspondence between their elements. The first name ("Louvre"), the first set number ("21024"), and the first number of pieces (695) all describe the first Lego set. +

    + zip() can be used to iterate over these three lists in parallel: +

    + Python +

    + Note how each line collects information from all three lists and shows information about one particular set. This is a very common pattern that’s used in a lot of different Python code, including in the standard library. +

    + You can also add list() to collect the contents of all three lists in a single, nested list of tuples: +

    + Python +

    + Note how the nested list closely resembles the original table. +

    + The dark side of using zip() is that it’s quite easy to introduce a subtle bug that can be hard to discover. Note what happens if there’s a missing item in one of your lists: +

    + Python +

    + All the information about the New York City set disappeared! Additionally, the set numbers for Saturn V and Millennium Falcon are wrong. If your datasets are bigger, these kinds of errors can be very hard to discover. And even when you observe that something’s wrong, it’s not always easy to diagnose and fix. +

    + The issue is that you assumed that the three lists have the same number of elements and that the information is in the same order in each list. After set_numbers gets corrupted, this assumption is no longer true. +

    + PEP 618 introduces a new strict keyword parameter to zip() that you can use to confirm all sequences have the same length. In your example, it would raise an error alerting you to the corrupted list: +

    + Python +

    + When the iteration reaches the New York City Lego set, the second argument set_numbers is already exhausted, while there are still elements left in the first argument names. Instead of silently giving the wrong result, your code fails with an error, and you can take action to find and fix the mistake. +

    + There are use cases when you want to combine sequences of unequal length. Expand the box below to see how zip() and itertools.zip_longest() handle these: +

    + The following idiom divides the Lego sets into pairs: +

    + Python +

    + There are five sets, a number that doesn’t divide evenly into pairs. In this case, the default behavior of zip(), where the last element is dropped, might make sense. You could use strict=True here as well, but that would raise an error when your list can’t be split into pairs. A third option, which could be the best in this case, is to use zip_longest() from the itertools standard library. +

    + As the name suggests, zip_longest() combines sequences until the longest sequence is exhausted. If you use zip_longest() to divide the Lego sets, it becomes more explicit that New York City doesn’t have any pairing: +

    + Python +

    + Note that 'NYC' shows up in the last tuple together with an empty string. You can control what’s filled in for missing values with the fillvalue parameter. +

    + While strict is not really adding any new functionality to zip(), it can help you avoid those hard-to-find bugs. +

    + New Functions in the statistics Module +

    + The statistics module was added to the standard library all the way back in 2014 with the release of Python 3.4. The intent of statistics is to make statistical calculations at the level of graphing calculators available in Python. +

    + Python 3.10 adds a few multivariable functions to statistics: +

    • correlation() to calculate Pearson’s correlation coefficient for two variables
    • covariance() to calculate sample covariance for two variables
    • linear_regression() to calculate the slope and intercept in a linear regression

    + You can use each function to describe a certain aspect of the relationship between two variables. As an example, say that you have data from a set of blog posts—the number of words in each blog post and the number of views each post has had over some time period: +

    + Python +

    + You now want to investigate whether there’s any (linear) relationship between the number of words and number of views. In Python 3.10, you can calculate the correlation between words and views with the new correlation() function: +

    + Python +

    + The correlation between two variables is always a number between -1 and 1. If it’s close to 0, then there’s little correspondence between them, while a correlation close to -1 or 1 indicates that the behaviors of the two variables tend to follow each other. In this example, a correlation of 0.45 indicates that there’s a tendency for posts with more words to have more views, although it’s not a strong connection. +

    + You can also calculate the covariance between words and views. The covariance is another measure of the joint variability between two variables. You can calculate it with covariance(): +

    + Python +

    + In contrast to correlation, covariance is an absolute measure. It should be interpreted in the context of the variability within the variables themselves. In fact, you can normalize the covariance by the standard deviation of each variable to recover Pearson’s correlation coefficient: +

    + Python +

    + Note that this matches your earlier correlation coefficient exactly. +

    + A third way of looking at the linear correspondence between the two variables is through simple linear regression. You do the linear regression by calculating two numbers, slope and intercept, so that the (squared) error is minimized in the approximation number of views = slope × number of words + intercept. +

    + In Python 3.10, you can use linear_regression(): +

    + Python +

    + Based on this regression, a post with 10,074 words could expect about 0.2424 × 10074 + 1104 = 3546 views. However, as you saw earlier, the correlation between the number of words and the number of views is quite weak. Therefore, you shouldn’t expect this prediction to be very accurate. +

    + The LinearRegression object is a named tuple. This means that you can unpack the slope and intercept directly: +

    + Python +

    + Here, you use slope and intercept to predict the number of views on a blog post with 10,074 words. +

    + You still want to use some of the more advanced packages like pandas and statsmodels if you do a lot of statistical analysis. With the new additions to statistics in Python 3.10, however, you have the chance to do basic analysis more easily without bringing in third-party dependencies. +

    + Other Pretty Cool Features +

    + So far, you’ve seen the biggest and most impactful new features in Python 3.10. In this section, you’ll get a glimpse of a few of the other changes that the new version brings along. If you’re curious about all the changes made for this new version, check out the documentation. +

    + Default Text Encodings +

    + When you open a text file, the default encoding used to interpret the characters is system dependent. In particular, locale.getpreferredencoding() is used. On Mac and Linux, this usually returns "UTF-8", while the result on Windows is more varied. +

    + You should therefore always specify an encoding when you attempt to open a text file: +

    + Python + +

    + If you don’t explicitly specify an encoding, the preferred locale encoding is used, and you could experience that a file that can be read on one computer fails to open on another. +

    + Python 3.7 introduced UTF-8 mode, which allows you to force your programs to use UTF-8 encoding independent of the locale encoding. You can enable UTF-8 mode by giving the -X utf8 command-line option to the python executable or by setting the PYTHONUTF8 environment variable. +

    + In Python 3.10, you can activate a warning that will tell you when a text file is opened without a specified encoding. Consider the following script, which doesn’t specify an encoding: +

    + Python + +

    + The program will echo one or more text files back to the console, but with each line reversed. Run the program on itself with the encoding warning enabled: +

    + Shell +

    + Note the EncodingWarning printed to the console. The command-line option -X warn_default_encoding activates it. The warning will disappear if you specify an encoding—for example, encoding="utf-8"—when you open the file. +

    + There are times when you want to use the user-defined local encoding. You can still do so by explicitly using encoding="locale". However, it’s recommended to use UTF-8 whenever possible. You can check out PEP 597 for more information. +

    + Asynchronous Iteration +

    + Asynchronous programming is a powerful programming paradigm that’s been available in Python since version 3.5. You can recognize an asynchronous program by its use of the async keyword or special methods that start with .__a like .__aiter__() or .__aenter__(). +

    + In Python 3.10, two new asynchronous built-in functions are added: aiter() and anext(). In practice, these functions call the .__aiter__() and .__anext__() special methods—analogous to the regular iter() and next()—so no new functionality is added. These are convenience functions that make your code more readable. +

    + In other words, in the newest version of Python, the following statements—where things is an asynchronous iterable—are equivalent: +

    + Python +

    + In either case, it ends up as an asynchronous iterator. Expand the following box to see a complete example using aiter() and anext(): +

    + The following program counts the number of lines in several files. In practice, you use Python’s ability to iterate over files to count the number of lines. The script uses asynchronous iteration in order to handle several files concurrently. +

    + Note that you need to install the third-party aiofiles package with pip before running this code: +

    + Python + +

    + asyncio is used to create and run one asynchronous task per filename. count_lines() opens one file asynchronously and iterates through it using aiter() and anext() in order to count the number of lines. +

    + See PEP 525 to learn more about asynchronous iteration. +

    + Context Manager Syntax +

    + Context managers are great for managing resources in your programs. Until recently, though, their syntax has included an uncommon wart. You haven’t been allowed to use parentheses to break long with statements like this: +

    + Python + +

    + In earlier versions of Python, this causes an invalid syntax error message. Instead, you need to use a backslash (\) if you want to control where you break your lines: +

    + Python + +

    + While explicit line continuation with backslashes is possible in Python, PEP 8 discourages it. The Black formatting tool avoids backslashes completely. +

    + In Python 3.10, you’re now allowed to add parentheses around with statements to your heart’s content. Especially if you’re employing several context managers at once, like in the example above, this can help improve the readability of your code. Python’s documentation shows a few other possibilities with this new syntax. +

    + One small fun fact: parenthesized with statements actually work in version 3.9 of CPython. Their implementation came almost for free with the introduction of the PEG parser in Python 3.9. The reason that this is called a Python 3.10 feature is that using the PEG parser is voluntary in Python 3.9, while Python 3.9, with the old LL(1) parser, doesn’t support parenthesized with statements. +

    + Modern and Secure SSL +

    + Security can be challenging! A good rule of thumb is to avoid rolling your own security algorithms and instead rely on established packages. +

    + Python uses OpenSSL for different cryptographic features that are exposed in the hashlib, hmac, and ssl standard library modules. Your system can manage OpenSSL, or a Python installer can include OpenSSL. +

    + Python 3.9 supports using any of the OpenSSL versions 1.0.2 LTS, 1.1.0, and 1.1.1 LTS. Both OpenSSL 1.0.2 LTS and OpenSSL 1.1.0 are past their lifetime, so Python 3.10 will only support OpenSSL 1.1.1 LTS, as described in the following table: +

    + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Open SSL version + + Python 3.9 + + Python 3.10 + + End-of-life +
    + 1.0.2 LTS + + ✔ + + ✖ + + December 20, 2019 +
    + 1.1.0 + + ✔ + + ✖ + + September 10, 2019 +
    + 1.1.1 LTS + + ✔ + + ✔ + + September 11, 2023 +

    + This end of support for older versions will only affect you if you need to upgrade the system Python on an older operating system. If you use macOS or Windows, or if you install Python from python.org or use (Ana)Conda, you’ll see no change. +

    + However, Ubuntu 18.04 LTS uses OpenSSL 1.1.0, while Red Hat Enterprise Linux (RHEL) 7 and CentOS 7 both use OpenSSL 1.0.2 LTS. If you need to run Python 3.10 on these systems, you should look at installing it yourself using either the python.org or Conda installer. +

    + Dropping support for older versions of OpenSSL will make Python more secure. It’ll also help the Python developers in that code will be easier to maintain. Ultimately, this helps you because your Python experience will be more robust. See PEP 644 for more details. +

    + More Information About Your Python Interpreter +

    + The sys module contains a lot of information about your system, the current Python runtime, and the script currently being executed. You can, for example, inquire about the paths where Python looks for modules with sys.path and see all modules that have been imported in the current session with sys.modules. +

    + In Python 3.10, sys has two new attributes. First, you can now get a list of the names of all modules in the standard library: +

    + Python +

    + Here, you can see that there are around 300 modules in the standard library, several of which start with the letter z. Note that only top-level modules and packages are listed. Subpackages like importlib.metadata don’t get a separate entry. +

    + You will probably not be using sys.stdlib_module_names all that often. Still, the list ties in nicely with similar introspection features like keyword.kwlist and sys.builtin_module_names. +

    + One possible use case for the new attribute is to identify which of the currently imported modules are third-party dependencies: +

    + Python +

    + You find the imported top-level modules by looking at names in sys.modules that don’t have a dot in their name. By comparing them to the standard library module names, you find that numpy, dateutil, and pandas are some of the imported third-party modules in this example. +

    + The other new attribute is sys.orig_argv. This is related to sys.argv, which holds the command-line arguments given to your program when it was started. In contrast, sys.orig_argv lists the command-line arguments passed to the python executable itself. Consider the following example: +

    + Python + +

    + This script echoes back the orig_argv and argv lists. Run it to see how the information is captured: +

    + Shell +

    + Essentially, all arguments—including the name of the Python executable—end up in orig_argv. This is in contrast to argv, which only contains the arguments that aren’t handled by python itself. +

    + Again, this is not a feature that you’ll use a lot. If your program needs to concern itself with how it’s being run, you’re usually better off relying on information that’s already exposed instead of trying to parse this list. For example, you can choose to use the strict zip() mode only when your script is not running with the optimized flag, -O, like this: +

    + Python + +

    + The __debug__ flag is set when the interpreter starts. It’ll be False if you’re running python with -O or -OO specified, and True otherwise. Using __debug__ is usually preferable to "-O" not in sys.orig_argv or some similar construct. +

    + One of the motivating use cases for sys.orig_argv is that you can use it to spawn a new Python process with the same or modified command-line arguments as your current process. +

    + Future Annotations +

    + Annotations were introduced in Python 3 to give you a way to attach metadata to variables, function parameters, and return values. They are most commonly used to add type hints to your code. +

    + One challenge with annotations is that they must be valid Python code. For one thing, this makes it hard to type hint recursive classes. PEP 563 introduced postponed evaluation of annotations, making it possible to annotate with names that haven’t yet been defined. Since Python 3.7, you can activate postponed evaluation of annotations with a __future__ import: +

    + Python + +

    + The intention was that postponed evaluation would become the default at some point in the future. After the 2020 Python Language Summit, it was decided to make this happen in Python 3.10. +

    + However, after more testing, it became clear that postponed evaluation didn’t work well for projects that use annotations at runtime. Key people in the FastAPI and the Pydantic projects voiced their concerns. At the last minute, it was decided to reschedule these changes for Python 3.11. +

    + To ease the transition into future behavior, a few changes have been made in Python 3.10 as well. Most importantly, a new inspect.get_annotations() function has been added. You should call this to access annotations at runtime: +

    + Python +

    + Check out Annotations Best Practices for details. +

    + How to Detect Python 3.10 at Runtime +

    + Python 3.10 is the first version of Python with a two-digit minor version number. While this is mostly an interesting fun fact and an indication that Python 3 has been around for quite some time, it does also have some practical consequences. +

    + When your code needs to do something specific based on the version of Python at runtime, you’ve gotten away with doing a lexicographical comparison of version strings until now. While it’s never been good practice, it’s been possible to do the following: +

    + Python + +

    + In Python 3.10, this code will raise SystemExit and stop your program. This happens because, as strings, "3.10" is less than "3.6". +

    + The correct way to compare version numbers is to use tuples of numbers: +

    + Python + +

    + sys.version_info is a tuple object you can use for comparisons. +

    + If you’re doing these kinds of comparisons in your code, you should check your code with flake8-2020 to make sure you’re handling versions correctly: +

    + Shell +

    + With the flake8-2020 extension activated, you’ll get a recommendation about replacing sys.version with sys.version_info. +

    + So, Should You Upgrade to Python 3.10? +

    + You’ve now seen the coolest features of the newest and latest version of Python. The question now is whether you should upgrade to Python 3.10, and if yes, when you should do so. There are two different aspects to consider when thinking about upgrading to Python 3.10: +

    1. Should you upgrade your environment so that you run your code with the Python 3.10 interpreter?
    2. Should you write your code using the new Python 3.10 features?

    + Clearly, if you want to test out structural pattern matching or any of the other cool new features you’ve read about here, you need Python 3.10. It’s possible to install the latest version side by side with your current Python version. A straightforward way to do this is to use an environment manager like pyenv or Conda. You can also use Docker to run Python 3.10 without installing it locally. +

    + Python 3.10 has been through about five months of beta testing, so there shouldn’t be any big issues with starting to use it for your own development. You may find that some of your dependencies don’t immediately have wheels for Python 3.10 available, which makes them more cumbersome to install. But in general, using the newest Python for local development is fairly safe. +

    + As always, you should be careful before upgrading your production environment. Be vigilant about testing that your code runs well on the new version. In particular, you want to be on the lookout for features that are deprecated or removed. +

    + Whether you can start using the new features in your code or not depends on your user base and the environment where your code is running. If you can guarantee that Python 3.10 is available, then there’s no danger in using the new union type syntax or any other new feature. +

    + If you’re distributing an app or a library that’s used by others instead, you may want to be a bit more conservative. Currently, Python 3.6 is the oldest officially supported Python version. It reaches end-of-life in December 2021, after which Python 3.7 will be the minimum supported version. +

    + The documentation includes a useful guide about porting your code to Python 3.10. Check it out for more details! +

    + Conclusion +

    + The release of a new Python version is always worth celebrating. Even if you can’t start using the new features right away, they’ll become broadly available and part of your daily life within a few years. +

    + In this tutorial, you’ve seen new features like: +

    • Friendlier error messages
    • Powerful structural pattern matching
    • Type hint improvements
    • Safer combination of sequences
    • New statistics functions

    + For more Python 3.10 tips and a discussion with members of the Real Python team, check out Real Python Podcast Episode #81. +

    + Have fun trying out the new features! Share your experiences in the comments below. +

    + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    + Get a short & sweet Python Trick delivered to your inbox every couple of days. No spam ever. Unsubscribe any time. Curated by the Real Python team. +

    Python Tricks Dictionary MergeGeir Arne HjelleGeir Arne Hjelle

    + Geir Arne is an avid Pythonista and a member of the Real Python tutorial team. +

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You went back to your code, and after a bit of staring and searching, you realized that there was a missing quotation mark at the end of your string.\n ", + -1, + 1, + "p", + 3, + "\n One of the more impactful improvements in Python 3.10 is better and more precise error messages for many common issues. If you run your buggy Hello World in Python 3.10, you’ll get a bit more help than in earlier versions of Python:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "console", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "$ ", + -1, + 3, + "python", + 1, + "span", + -1, + 3, + "hello.py\n", + 1, + "span", + 3, + " File \"/home/rp/hello.py\", line 3", + -1, + 1, + "span", + 3, + " print(\"Hello, World!)", + -1, + 1, + "span", + 3, + " ^", + -1, + 1, + "span", + 3, + "SyntaxError: unterminated string literal (detected at line 3)", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The error message is still a bit technical, but gone is the mysterious ", + 1, + "code", + 3, + "EOL", + -1, + 3, + ". Instead, the message tells you that you need to terminate your string! There are similar improvements to many different error messages, as you’ll see below.\n ", + -1, + 1, + "p", + 3, + "\n A ", + 1, + "a", + 2, + "href", + "https://realpython.com/invalid-syntax-python/", + 1, + "code", + 3, + "SyntaxError", + -2, + 3, + " is an error raised when your code is parsed, before it even starts to execute. Syntax errors can be tricky to debug because the interpreter provides imprecise or sometimes even misleading error messages. The following code is missing a curly brace to terminate the dictionary:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + " 1", + -1, + 1, + "span", + 3, + "# unterminated_dict.py", + -1, + 1, + "span", + 3, + " 2", + -1, + 1, + "span", + 3, + " 3", + -1, + 1, + "span", + 3, + "months", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + " 4", + -1, + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"October\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + " 5", + -1, + 1, + "span", + 3, + "11", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"November\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + " 6", + -1, + 1, + "span", + 3, + "12", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"December\"", + -1, + 1, + "span", + 3, + " 7", + -1, + 1, + "span", + 3, + " 8", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "months", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + " is the tenth month\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The missing closing curly brace that should have been on line 7 is an error. If you run this code with Python 3.9 or earlier, you’ll see the following error message:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "pytb", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 3, + " File ", + 1, + "span", + 3, + "\"/home/rp/unterminated_dict.py\"", + -1, + 3, + ", line ", + 1, + "span", + 3, + "8", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "months", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + " is the tenth month\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "^", + -1, + 1, + "span", + 3, + "SyntaxError", + -1, + 3, + ": ", + 1, + "span", + 3, + "invalid syntax", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The error message highlights line 8, but there are no syntactical problems in line 8! If you’ve experienced your share of syntax errors in Python, you might already know that the trick is to look at the lines ", + 1, + "em", + 3, + "before", + -1, + 3, + " the one Python complains about. In this case, you’re looking for the missing closing brace on line 7.\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, the same code shows a much more helpful and precise error message:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "pytb", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 3, + " File ", + 1, + "span", + 3, + "\"/home/rp/unterminated_dict.py\"", + -1, + 3, + ", line ", + 1, + "span", + 3, + "3", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "months", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "^", + -1, + 1, + "span", + 3, + "SyntaxError", + -1, + 3, + ": ", + 1, + "span", + 3, + "'{' was never closed", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n This points you straight to the offending dictionary and allows you to fix the issue in no time.\n ", + -1, + 1, + "p", + 3, + "\n There are a few other ways to mess up dictionary syntax. A typical one is forgetting a comma after one of the items:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + " 1", + -1, + 1, + "span", + 3, + "# missing_comma.py", + -1, + 1, + "span", + 3, + " 2", + -1, + 1, + "span", + 3, + " 3", + -1, + 1, + "span", + 3, + "months", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 1, + "span", + 3, + " 4", + -1, + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"October\"", + -2, + 1, + "span", + 3, + " 5", + -1, + 1, + "span", + 3, + "11", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"November\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + " 6", + -1, + 1, + "span", + 3, + "12", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"December\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + " 7", + -1, + 1, + "span", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n In this code, a comma is missing at the end of line 4. Python 3.10 gives you a clear suggestion on how to fix your code:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "pytb", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 3, + " File ", + 1, + "span", + 3, + "\"/home/real_python/missing_comma.py\"", + -1, + 3, + ", line ", + 1, + "span", + 3, + "4", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"October\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "^^^^^^^^^", + -1, + 1, + "span", + 3, + "SyntaxError", + -1, + 3, + ": ", + 1, + "span", + 3, + "invalid syntax. Perhaps you forgot a comma?", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You can add the missing comma and have your code back up and running in no time.\n ", + -1, + 1, + "p", + 3, + "\n Another common mistake is using the ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-assignment-operator/", + 3, + "assignment operator", + -1, + 3, + " (", + 1, + "code", + 3, + "=", + -1, + 3, + ") instead of the equality comparison operator (", + 1, + "code", + 3, + "==", + -1, + 3, + ") when you’re comparing values. Previously, this would just cause another ", + 1, + "code", + 3, + "invalid syntax", + -1, + 3, + " message. In the newest version of Python, you get some more advice:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "month", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"October\"", + -1, + 1, + "span", + 3, + ":", + -1, + 3, + "\n File ", + 1, + "span", + 3, + "\"", + 3, + "<", + 3, + "stdin", + 3, + ">", + 3, + "\"", + -1, + 3, + ", line ", + 1, + "span", + 3, + "1", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "month", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"October\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "^^^^^^^^^^^^^^^^^", + -1, + 1, + "span", + 3, + "SyntaxError", + -1, + 3, + ": ", + 1, + "span", + 3, + "invalid syntax. Maybe you meant '==' or ':=' instead of '='?", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The parser suggests that you maybe meant to use a ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-operators-expressions/#comparison-operators", + 3, + "comparison operator", + -1, + 3, + " or an ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-walrus-operator/", + 3, + "assignment expression operator", + -1, + 3, + " instead.\n ", + -1, + 1, + "p", + 3, + "\n Take note of another nifty improvement in Python 3.10 error messages. The last two examples show how carets (", + 1, + "code", + 3, + "^^^", + -1, + 3, + ") highlight the whole offending expression. Previously, a single caret symbol (", + 1, + "code", + 3, + "^", + -1, + 3, + ") indicated just an approximate location.\n ", + -1, + 1, + "p", + 3, + "\n The final error message improvement that you’ll play with for now is that attribute and name errors can now offer suggestions if you misspell an attribute or a name:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "math", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "math", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "py", + -1, + 1, + "span", + 1, + "span", + 3, + "AttributeError: module 'math' has no attribute 'py'. Did you mean: 'pi'?", + -2, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "pint", + -1, + 1, + "span", + 1, + "span", + 3, + "NameError: name 'pint' is not defined. Did you mean: 'print'?", + -2, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "release", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"3.10\"", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "relaese", + -1, + 1, + "span", + 1, + "span", + 3, + "NameError: name 'relaese' is not defined. Did you mean: 'release'?", + -5, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that the suggestions work for both built-in names and names that you define yourself, although they may ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#attributeerrors", + 3, + "not be available", + -1, + 3, + " in all environments. If you like these kinds of suggestions, check out ", + 1, + "a", + 2, + "href", + "https://github.com/SylvainDe/DidYouMean-Python", + 3, + "BetterErrorMessages", + -1, + 3, + ", which offers similar suggestions in even more contexts.\n ", + -1, + 1, + "p", + 3, + "\n The improvements you’ve seen in this section are just some of the ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#better-error-messages", + 3, + "many error messages", + -1, + 3, + " that have gotten a face-lift. The new Python will be even more user-friendly than before, and hopefully, the new error messages will save you both time and frustration going forward.\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "structural-pattern-matching", + 3, + "\n Structural Pattern Matching", + 1, + "a", + 2, + "href", + "#structural-pattern-matching", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n The biggest new feature in Python 3.10, probably both in terms of ", + 1, + "a", + 2, + "href", + "https://lwn.net/Articles/845480/", + 3, + "controversy", + -1, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Pattern_matching", + 3, + "potential impact", + -1, + 3, + ", is ", + 1, + "strong", + 3, + "structural pattern matching", + -1, + 3, + ". Its introduction has sometimes been referred to as ", + 1, + "code", + 3, + "switch ... case", + -1, + 3, + " coming to Python, but you’ll see that structural pattern matching is much more powerful than that.\n ", + -1, + 1, + "p", + 3, + "\n You’ll see three different examples that together highlight why this feature is called structural pattern matching and show you how you can use this new feature:\n ", + -1, + 1, + "ol", + 1, + "li", + 3, + "Detecting and deconstructing different ", + 1, + "strong", + 3, + "structures", + -1, + 3, + " in your data\n ", + -1, + 1, + "li", + 3, + "Using different kinds of ", + 1, + "strong", + 3, + "patterns", + -2, + 1, + "li", + 1, + "strong", + 3, + "Matching", + -1, + 3, + " literal patterns\n ", + -2, + 1, + "p", + 3, + "\n Structural pattern matching is a comprehensive addition to the Python language. To give you a taste of how you can take advantage of it in your own projects, the next three subsections will dive into some of the details. You’ll also see some links that can help you explore in even more depth if you want.\n ", + -1, + 1, + "section", + 1, + "h3", + 2, + "id", + "deconstructing-data-structures", + 3, + "\n Deconstructing Data Structures", + 1, + "a", + 2, + "href", + "#deconstructing-data-structures", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n At its core, structural pattern matching is about defining patterns to which your data structures can be matched. In this section, you’ll study a practical example where you’ll work with data that are structured differently, even though the meaning is the same. You’ll define several patterns, and depending on which pattern matches your data, you’ll process your data appropriately.\n ", + -1, + 1, + "p", + 3, + "\n This section will be a bit light on explanations of the possible patterns. Instead, it will try to give you an impression of the possibilities. The next section will step back and explain the patterns in more detail.\n ", + -1, + 1, + "p", + 3, + "\n Time to match your first pattern! The following example uses a ", + 1, + "code", + 3, + "match ... case", + -1, + 3, + " block to find the first name of a user by extracting it from a ", + 1, + "code", + 3, + "user", + -1, + 3, + " data structure:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "user", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"first\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"Pablo\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"last\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"Galindo Salgado\"", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "\"title\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "\"Python 3.10 release manager\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "user", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"first\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "first_name", + -1, + 1, + "span", + 3, + "}}:", + -2, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "pass", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "first_name", + -1, + 1, + "span", + 3, + "'Pablo'", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You can see structural pattern matching at work in the highlighted lines. ", + 1, + "code", + 3, + "user", + -1, + 3, + " is a small dictionary with user information. The ", + 1, + "code", + 3, + "case", + -1, + 3, + " line specifies a pattern that ", + 1, + "code", + 3, + "user", + -1, + 3, + " is matched against. In this case, you’re looking for a dictionary with a ", + 1, + "code", + 3, + "\"name\"", + -1, + 3, + " key whose value is a new dictionary. This nested dictionary has a key called ", + 1, + "code", + 3, + "\"first\"", + -1, + 3, + ". The corresponding value is bound to the variable ", + 1, + "code", + 3, + "first_name", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n For a practical example, say that you’re processing user data where the underlying data model changes over time. Therefore, you need to be able to process different versions of the same data.\n ", + -1, + 1, + "p", + 3, + "\n In the next example, you’ll use data from ", + 1, + "a", + 2, + "href", + "https://randomuser.me/", + 3, + "randomuser.me", + -1, + 3, + ". This is a great API for generating random user data that you can use during testing and development. The API is also an example of an API that has changed over time. You can still access the ", + 1, + "a", + 2, + "href", + "https://randomuser.me/documentation#previous", + 3, + "old versions", + -1, + 3, + " of the API.\n ", + -1, + 1, + "p", + 3, + "\n You may expand the collapsed section below to see how you can use ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-requests/", + 1, + "code", + 3, + "requests", + -2, + 3, + " to obtain different versions of the user data using the API:\n ", + -1, + 1, + "div", + 2, + "id", + "collapse_cardbb4757", + 2, + "data-parent", + "#collapse_cardbb4757", + 1, + "p", + 3, + "\n You can get a random user from the API using ", + 1, + "code", + 3, + "requests", + -1, + 3, + " as follows:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# random_user.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "requests", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "get_user", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "version", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"1.3\"", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"\"\"Get random users\"\"\"", + -1, + 1, + "span", + 3, + "url", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "version", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "/?results=1\"", + -1, + 1, + "span", + 3, + "response", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "requests", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "url", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "response", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "response", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "json", + -1, + 1, + "span", + 3, + "()[", + -1, + 1, + "span", + 3, + "\"results\"", + -1, + 1, + "span", + 3, + "][", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 1, + "code", + 3, + "get_user()", + -1, + 3, + " gets one random user in ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-json/", + 3, + "JSON", + -1, + 3, + " format. Note the ", + 1, + "code", + 3, + "version", + -1, + 3, + " parameter. The structure of the returned data has changed quite a bit between earlier versions like ", + 1, + "code", + 3, + "\"1.1\"", + -1, + 3, + " and the current version ", + 1, + "code", + 3, + "\"1.3\"", + -1, + 3, + ", but in each case, the actual user data are contained in a list inside the ", + 1, + "code", + 3, + "\"results\"", + -1, + 3, + " array. The function returns the first—and only—user in this list.\n ", + -1, + 1, + "p", + 3, + "\n At the time of writing, the latest version of the API is 1.3 and the data has the following structure:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "json", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"gender\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"female\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"title\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Miss\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"first\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Ilona\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"last\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Jokela\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"location\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"street\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"number\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "4473", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Mannerheimintie\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"city\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Harjavalta\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"state\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Ostrobothnia\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"country\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Finland\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"postcode\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "44879", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"coordinates\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"latitude\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"-6.0321\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"longitude\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"123.2213\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"timezone\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"offset\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"+5:30\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"description\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"Bombay, Calcutta, Madras, New Delhi\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"email\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"ilona.jokela@example.com\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"login\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"uuid\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"632b7617-6312-4edf-9c24-d6334a6af52d\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"username\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"brownsnake482\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"password\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"biatch\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"salt\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"ofk518ZW\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"md5\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"6d589615ca44f6e583c85d45bf431c54\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"sha1\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"cd87c931d579bdff77af96c09e0eea82d1edfc19\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"sha256\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"6038ede83d4ce74116faa67fb3b1b2e6f6898e5749b57b5a0312bd46a539214a\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + 1, + "span", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -2, + 1, + "span", + 1, + "span", + -1, + 1, + "span", + 3, + "\"age\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "64", + -2, + 1, + "span", + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -2, + 1, + "span", + -1, + 1, + "span", + 3, + "\"registered\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"date\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"age\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "15", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"phone\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"07-369-318\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"cell\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"048-284-01-59\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"id\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"HETU\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"value\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"NaNNA204undefined\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"picture\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"large\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/women/28.jpg\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"medium\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/med/women/28.jpg\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"thumbnail\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/thumb/women/28.jpg\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"nat\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"FI\"", + -1, + 1, + "span", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n One of the members that changed between different versions is ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + ", the date of birth. Note that in version 1.3, this is a JSON object with two members, ", + 1, + "code", + 3, + "\"date\"", + -1, + 3, + " and ", + 1, + "code", + 3, + "\"age\"", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n Compare the result above with a version 1.1 random user:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "json", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"gender\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"female\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"title\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"miss\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"first\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"ilona\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"last\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"jokela\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"location\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"street\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"7336 myllypuronkatu\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"city\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"kurikka\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"state\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"central ostrobothnia\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"postcode\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "53740", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"email\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"ilona.jokela@example.com\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"login\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"username\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"blackelephant837\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"password\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"sand\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"salt\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"yofk518Z\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"md5\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"b26367ea967600d679ee3e0b9bda012f\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"sha1\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"87d2910595acba5b8e8aa8b00a841bab08580e2f\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"sha256\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"73bd0d205d0dc83ae184ae222ff2e9de5ea4039119a962c4f97fabd5bbfa7aca\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"registered\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"phone\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"04-636-931\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"cell\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"048-828-40-15\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"id\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"name\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"HETU\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"value\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"366-9204\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"picture\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"large\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/women/24.jpg\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"medium\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/med/women/24.jpg\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"thumbnail\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"https://randomuser.me/api/portraits/thumb/women/24.jpg\"", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"nat\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"FI\"", + -1, + 1, + "span", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Observe that in this older format, the value of the ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " member is a plain string.\n ", + -2, + 1, + "p", + 3, + "\n In this example, you’ll work with the information about the date of birth (", + 1, + "code", + 3, + "dob", + -1, + 3, + ") for each user. The structure of these data has changed between different versions of the Random User API:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "json", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "#", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "Versio", + -1, + 1, + "span", + 3, + "n", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "1.1", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "#", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "Versio", + -1, + 1, + "span", + 3, + "n", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "1.3", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"date\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"age\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "64", + -1, + 1, + "span", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that in version 1.1, the date of birth is represented as a simple string, while in version 1.3, it’s a JSON object with two members: ", + 1, + "code", + 3, + "\"date\"", + -1, + 3, + " and ", + 1, + "code", + 3, + "\"age\"", + -1, + 3, + ". Say that you want to find the age of a user. Depending on the structure of your data, you’d either need to calculate the age based on the date of birth or look up the age if it’s already available.\n ", + -1, + 1, + "p", + 3, + "\n Traditionally, you would detect the structure of the data with an ", + 1, + "code", + 3, + "if", + -1, + 3, + " test, maybe based on the type of the ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " field. You can approach this differently in Python 3.10. Now, you can use structural pattern matching instead:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + " 1", + -1, + 1, + "span", + 3, + "# random_user.py (continued)", + -1, + 1, + "span", + 3, + " 2", + -1, + 1, + "span", + 3, + " 3", + -1, + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "datetime", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "datetime", + -1, + 1, + "span", + 3, + " 4", + -1, + 1, + "span", + 3, + " 5", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "get_age", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "user", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + " 6", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"\"\"Get the age of a user\"\"\"", + -1, + 1, + "span", + 1, + "span", + 3, + " 7", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "user", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 1, + "span", + 3, + " 8", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"age\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "age", + -1, + 1, + "span", + 3, + ")}}:", + -2, + 1, + "span", + 3, + " 9", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "age", + -1, + 1, + "span", + 1, + "span", + 3, + "10", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "dob", + -1, + 1, + "span", + 3, + "}:", + -2, + 1, + "span", + 3, + "11", + -1, + 1, + "span", + 3, + "now", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "datetime", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "now", + -1, + 1, + "span", + 3, + "()", + -1, + 1, + "span", + 3, + "12", + -1, + 1, + "span", + 3, + "dob_date", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "datetime", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "strptime", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "dob", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"%Y-%m-", + -1, + 1, + "span", + 3, + "%d", + -1, + 1, + "span", + 3, + " %H:%M:%S\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "13", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "now", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "year", + -1, + 1, + "span", + 3, + "-", + -1, + 1, + "span", + 3, + "dob_date", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "year", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The ", + 1, + "code", + 3, + "match ... case", + -1, + 3, + " construct is new in Python 3.10 and is how you perform structural pattern matching. You start with a ", + 1, + "code", + 3, + "match", + -1, + 3, + " statement that specifies what you want to match. In this example, that’s the ", + 1, + "code", + 3, + "user", + -1, + 3, + " data structure.\n ", + -1, + 1, + "p", + 3, + "\n One or several ", + 1, + "code", + 3, + "case", + -1, + 3, + " statements follow ", + 1, + "code", + 3, + "match", + -1, + 3, + ". Each ", + 1, + "code", + 3, + "case", + -1, + 3, + " describes one pattern, and the indented block beneath it says what should happen if there’s a match. In this example:\n ", + -1, + 1, + "ul", + 1, + "li", + 1, + "p", + 1, + "strong", + 3, + "Line 8", + -1, + 3, + " matches a dictionary with a ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " key whose value is another dictionary with an integer (", + 1, + "code", + 3, + "int", + -1, + 3, + ") item named ", + 1, + "code", + 3, + "\"age\"", + -1, + 3, + ". The name ", + 1, + "code", + 3, + "age", + -1, + 3, + " captures its value.\n ", + -2, + 1, + "li", + 1, + "p", + 1, + "strong", + 3, + "Line 10", + -1, + 3, + " matches any dictionary with a ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " key. The name ", + 1, + "code", + 3, + "dob", + -1, + 3, + " captures its value.\n ", + -3, + 1, + "p", + 3, + "\n One important feature of pattern matching is that at most one pattern will be matched. Since the pattern on line 10 matches any dictionary with ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + ", it’s important that the more specific pattern on line 8 comes first.\n ", + -1, + 1, + "p", + 3, + "\n Before looking closer at the details of the patterns and how they work, try calling ", + 1, + "code", + 3, + "get_age()", + -1, + 3, + " with different data structures to see the result:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "random_user", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "users11", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "random_user", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get_user", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "version", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"1.1\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "random_user", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get_age", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "users11", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "55", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "users13", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "random_user", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get_user", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "version", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"1.3\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "random_user", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get_age", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "users13", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "64", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Your code can calculate the age correctly for both versions of the user data, which have different dates of birth.\n ", + -1, + 1, + "p", + 3, + "\n Look closer at those patterns. The first pattern, ", + 1, + "code", + 3, + "{\"dob\": {\"age\": int(age)}}", + -1, + 3, + ", matches version 1.3 of the user data:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "\"dob\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "\"date\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"age\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "64", + -1, + 1, + "span", + 3, + "},", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The first pattern is a nested pattern. The outer curly braces say that a dictionary with the key ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " is required. The corresponding value should be a dictionary. This nested dictionary must match the subpattern ", + 1, + "code", + 3, + "{\"age\": int(age)}", + -1, + 3, + ". In other words, it needs to have an ", + 1, + "code", + 3, + "\"age\"", + -1, + 3, + " key with an integer value. That value is bound to the name ", + 1, + "code", + 3, + "age", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n The second pattern, ", + 1, + "code", + 3, + "{\"dob\": dob}", + -1, + 3, + ", matches the older version 1.1 of the user data:\n ", + -1, + 1, + "p", + 3, + "\n This second pattern is a simpler pattern than the first one. Again, the curly braces indicate that it will match a dictionary. However, any dictionary with a ", + 1, + "code", + 3, + "\"dob\"", + -1, + 3, + " key is matched because there are no other restrictions specified. The value of that key is bound to the name ", + 1, + "code", + 3, + "dob", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n The main takeaway is that you can describe the structure of your data using mostly familiar notation. One striking change, though, is that you can use names like ", + 1, + "code", + 3, + "dob", + -1, + 3, + " and ", + 1, + "code", + 3, + "age", + -1, + 3, + ", which aren’t yet defined. Instead, values from your data are ", + 1, + "strong", + 3, + "bound", + -1, + 3, + " to these names when a pattern matches.\n ", + -1, + 1, + "p", + 3, + "\n You’ve explored some of the power of structural pattern matching in this example. In the next section, you’ll dive a bit more into the details.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "using-different-kinds-of-patterns", + 3, + "\n Using Different Kinds of Patterns", + 1, + "a", + 2, + "href", + "#using-different-kinds-of-patterns", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n You’ve seen an example of how you can use patterns to effectively unravel complicated data structures. Now, you’ll take a step back and look at the building blocks that make up this new feature. Many things come together to make it work. In fact, there are three ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0001/#what-is-a-pep", + 3, + "Python Enhancement Proposals", + -1, + 3, + " (PEPs) that describe structural pattern matching:\n ", + -1, + 1, + "ol", + 1, + "li", + 1, + "strong", + 3, + "PEP 634:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0634/", + 3, + "Specification", + -2, + 1, + "li", + 1, + "strong", + 3, + "PEP 635:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0635/", + 3, + "Motivation and Rationale", + -2, + 1, + "li", + 1, + "strong", + 3, + "PEP 636:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0636/", + 3, + "Tutorial", + -3, + 1, + "p", + 3, + "\n These documents give you a lot of background and detail if you’re interested in a deeper dive than what follows.\n ", + -1, + 1, + "p", + 3, + "\n Patterns are at the center of structural pattern matching. In this section, you’ll learn about some of the different kinds of patterns that exist:\n ", + -1, + 1, + "ul", + 1, + "li", + 1, + "strong", + 3, + "Mapping patterns", + -1, + 3, + " match mapping structures like dictionaries.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Sequence patterns", + -1, + 3, + " match sequence structures like tuples and lists.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Capture patterns", + -1, + 3, + " bind values to names.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "AS patterns", + -1, + 3, + " bind the value of subpatterns to names.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "OR patterns", + -1, + 3, + " match one of several different subpatterns.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Wildcard patterns", + -1, + 3, + " match anything.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Class patterns", + -1, + 3, + " match class structures.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Value patterns", + -1, + 3, + " match values stored in attributes.\n ", + -1, + 1, + "li", + 1, + "strong", + 3, + "Literal patterns", + -1, + 3, + " match literal values.\n ", + -2, + 1, + "p", + 3, + "\n You already used several of them in the example in the previous section. In particular, you used ", + 1, + "strong", + 3, + "mapping patterns", + -1, + 3, + " to unravel data stored in dictionaries. In this section, you’ll learn more about how some of these work. All the details are available in the PEPs mentioned above.\n ", + -1, + 1, + "p", + 3, + "\n A ", + 1, + "strong", + 3, + "capture pattern", + -1, + 3, + " is used to capture a match to a pattern and bind it to a name. Consider the following ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-recursion/", + 3, + "recursive", + -1, + 3, + " function that sums a list of numbers:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + " 1", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + " 2", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + " 3", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[]:", + -1, + 1, + "span", + 3, + " 4", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 1, + "span", + 3, + " 5", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + "]:", + -2, + 1, + "span", + 3, + " 6", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "+", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The first ", + 1, + "code", + 3, + "case", + -1, + 3, + " on line 3 matches the empty list and returns ", + 1, + "code", + 3, + "0", + -1, + 3, + " as its sum. The second ", + 1, + "code", + 3, + "case", + -1, + 3, + " on line 5 uses a ", + 1, + "strong", + 3, + "sequence pattern", + -1, + 3, + " with two capture patterns to match lists with one or more elements. The first element in the list is captured and bound to the name ", + 1, + "code", + 3, + "first", + -1, + 3, + ". The second capture pattern, ", + 1, + "code", + 3, + "*rest", + -1, + 3, + ", uses ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-kwargs-and-args/#unpacking-with-the-asterisk-operators", + 3, + "unpacking syntax", + -1, + 3, + " to match any number of elements. ", + 1, + "code", + 3, + "rest", + -1, + 3, + " will bind to a list containing all elements of ", + 1, + "code", + 3, + "numbers", + -1, + 3, + " except the first one.\n ", + -1, + 1, + "p", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " calculates the sum of a list of numbers by recursively adding the first number in the list and the sum of the rest of the numbers. You can use it as follows:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "([", + -1, + 1, + "span", + 3, + "4", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "5", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "9", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "4", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "22", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The sum of 4 + 5 + 9 + 4 is correctly calculated to be 22. As an exercise for yourself, you can try to trace the recursive calls to ", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " to make sure you understand how the code sums the whole list.\n ", + -1, + 1, + "p", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " handles summing up a list of numbers. Observe what happens if you try to sum anything that isn’t a list:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"4594\"", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "None", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "4594", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "None", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Passing a string or a number to ", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " returns ", + 1, + "code", + 3, + "None", + -1, + 3, + ". This occurs because none of the patterns match, and the execution continues after the ", + 1, + "code", + 3, + "match", + -1, + 3, + " block. That happens to be the end of the function, so ", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " implicitly ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-return-statement/#implicit-return-statements", + 3, + "returns ", + 1, + "code", + 3, + "None", + -2, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n Often, though, you want to be alerted about failed matches. You can add a catchall pattern as the final case that handles this by raising an error, for example. You can use the underscore (", + 1, + "code", + 3, + "_", + -1, + 3, + ") as a ", + 1, + "strong", + 3, + "wildcard pattern", + -1, + 3, + " that matches anything without binding it to a name. You can add some error handling to ", + 1, + "code", + 3, + "sum_list()", + -1, + 3, + " as follows:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[]:", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + "]:", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "+", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "wrong_type", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "__class__", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "__name__", + -1, + 1, + "span", + 3, + "raise", + -1, + 1, + "span", + 3, + "ValueError", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"Can only sum lists, not ", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "wrong_type", + -1, + 1, + "span", + 3, + "!r}", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The final ", + 1, + "code", + 3, + "case", + -1, + 3, + " will match anything that doesn’t match the first two patterns. This will raise a descriptive error, for instance, if you try to calculate ", + 1, + "code", + 3, + "sum_list(4594)", + -1, + 3, + ". This is useful when you need to alert your users that some input was not matched as expected.\n ", + -1, + 1, + "p", + 3, + "\n Your patterns are still not foolproof, though. Consider what happens if you try to sum a list of strings:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "([", + -1, + 1, + "span", + 3, + "\"45\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"94\"", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "TypeError: can only concatenate str (not \"int\") to str", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The base case returns ", + 1, + "code", + 3, + "0", + -1, + 3, + ", so therefore the summing only works for types that you can add with numbers. Python doesn’t know how to add numbers and text strings together. You can restrict your pattern to only match integers using a ", + 1, + "strong", + 3, + "class pattern", + -1, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[]:", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "),", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + "]:", + -2, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "+", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "raise", + -1, + 1, + "span", + 3, + "ValueError", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"Can only sum lists of numbers\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Adding ", + 1, + "code", + 3, + "int()", + -1, + 3, + " around ", + 1, + "code", + 3, + "first", + -1, + 3, + " makes sure that the pattern only matches if the value is an integer. This might be too restrictive, though. Your function should be able to sum both ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-numbers/#integers", + 3, + "integers", + -1, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-numbers/#floating-point-numbers", + 3, + "floating-point numbers", + -1, + 3, + ", so how can you allow this in your pattern?\n ", + -1, + 1, + "p", + 3, + "\n To check whether at least one out of several subpatterns match, you can use an ", + 1, + "strong", + 3, + "OR pattern", + -1, + 3, + ". OR patterns consist of two or more subpatterns, and the pattern matches if at least one of the subpatterns does. You can use this to match when the first element is either of type ", + 1, + "code", + 3, + "int", + -1, + 3, + " or type ", + 1, + "code", + 3, + "float", + -1, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[]:", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "),", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + "]:", + -2, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "first", + -1, + 1, + "span", + 3, + "+", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "rest", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "raise", + -1, + 1, + "span", + 3, + "ValueError", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"Can only sum lists of numbers\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You use the pipe symbol (", + 1, + "code", + 3, + "|", + -1, + 3, + ") to separate the subpatterns in an OR pattern. Your function now allows summing a list of floating-point numbers:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "sum_list", + -1, + 1, + "span", + 3, + "([", + -1, + 1, + "span", + 3, + "45.94", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "46.17", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "46.72", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "138.82999999999998", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n There’s a lot of power and flexibility within structural pattern matching, even more than what you’ve seen so far. Some things that aren’t covered in this overview are:\n ", + -1, + 1, + "ul", + 1, + "li", + 3, + "Using ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0635/#guards", + 3, + "guards", + -1, + 3, + " to restrict patterns\n ", + -1, + 1, + "li", + 3, + "Using ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0635/#as-patterns", + 3, + "AS patterns", + -1, + 3, + " to capture the value of subpatterns\n ", + -1, + 1, + "li", + 3, + "Using ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0636/#matching-positional-attributes", + 3, + "class patterns", + -1, + 3, + " to match custom ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/enum.html", + 3, + "enums", + -1, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-data-classes/", + 3, + "data classes", + -3, + 1, + "p", + 3, + "\n If you’re interested, have a look in the documentation to learn more about these features as well. In the next section, you’ll learn about literal patterns and value patterns.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "matching-literal-patterns", + 3, + "\n Matching Literal Patterns", + 1, + "a", + 2, + "href", + "#matching-literal-patterns", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n A ", + 1, + "strong", + 3, + "literal pattern", + -1, + 3, + " is a pattern that matches a literal object like an explicit string or number. In a sense, this is the most basic kind of pattern and allows you to emulate ", + 1, + "code", + 3, + "switch ... case", + -1, + 3, + " statements seen in other languages. The following example matches a specific name:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "greet", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "\"Guido\"", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Hi, Guido!\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Howdy, stranger!\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The first ", + 1, + "code", + 3, + "case", + -1, + 3, + " matches the literal string ", + 1, + "code", + 3, + "\"Guido\"", + -1, + 3, + ". In this case, you use ", + 1, + "code", + 3, + "_", + -1, + 3, + " as a wildcard to print a generic greeting whenever ", + 1, + "code", + 3, + "name", + -1, + 3, + " is not ", + 1, + "code", + 3, + "\"Guido\"", + -1, + 3, + ". Such literal patterns can sometimes take the place of ", + 1, + "code", + 3, + "if ... elif ... else", + -1, + 3, + " constructs and can play the same role that ", + 1, + "code", + 3, + "switch ... case", + -1, + 3, + " does in some other languages.\n ", + -1, + 1, + "p", + 3, + "\n One limitation with structural pattern matching is that you can’t directly match values stored in variables. Say that you’ve defined ", + 1, + "code", + 3, + "bdfl = \"Guido\"", + -1, + 3, + ". A pattern like ", + 1, + "code", + 3, + "case bdfl:", + -1, + 3, + " will not match ", + 1, + "code", + 3, + "\"Guido\"", + -1, + 3, + ". Instead, this will be interpreted as a capture pattern that matches anything and binds that value to ", + 1, + "code", + 3, + "bdfl", + -1, + 3, + ", effectively overwriting the old value.\n ", + -1, + 1, + "p", + 3, + "\n You can, however, use a ", + 1, + "strong", + 3, + "value pattern", + -1, + 3, + " to match stored values. A value pattern looks a bit like a capture pattern but uses a previously defined dotted name that holds the value that will be matched against.\n ", + -1, + 1, + "p", + 3, + "\n You can, for example, use an ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/enum.html", + 3, + "enumeration", + -1, + 3, + " to create such dotted names:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "enum", + -1, + 1, + "span", + 3, + "class", + -1, + 1, + "span", + 3, + "Pythonista", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "enum", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "Enum", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "BDFL", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"Guido\"", + -1, + 1, + "span", + 3, + "FLUFL", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"Barry\"", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "greet", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "Pythonista", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "BDFL", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Hi, Guido!\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Howdy, stranger!\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The first case now uses a value pattern to match ", + 1, + "code", + 3, + "Pythonista.BDFL", + -1, + 3, + ", which is ", + 1, + "code", + 3, + "\"Guido\"", + -1, + 3, + ". Note that you can use any dotted name in a value pattern. You could, for example, have used a regular class or a module instead of the enumeration.\n ", + -1, + 1, + "p", + 3, + "\n To see a bigger example of how to use literal patterns, consider the game of ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Fizz_buzz", + 3, + "FizzBuzz", + -1, + 3, + ". This is a counting game where you should replace some numbers with words according to the following rules:\n ", + -1, + 1, + "ul", + 1, + "li", + 3, + "You replace numbers divisible by ", + 1, + "strong", + 3, + "3", + -1, + 3, + " with ", + 1, + "strong", + 3, + "fizz", + -1, + 3, + ".\n ", + -1, + 1, + "li", + 3, + "You replace numbers divisible by ", + 1, + "strong", + 3, + "5", + -1, + 3, + " with ", + 1, + "strong", + 3, + "buzz", + -1, + 3, + ".\n ", + -1, + 1, + "li", + 3, + "You replace numbers divisible by both ", + 1, + "strong", + 3, + "3", + -1, + 3, + " and ", + 1, + "strong", + 3, + "5", + -1, + 3, + " with ", + 1, + "strong", + 3, + "fizzbuzz", + -1, + 3, + ".\n ", + -2, + 1, + "p", + 3, + "\n FizzBuzz is sometimes used to introduce conditionals in programming education and as a screening problem in interviews. Even though a solution is quite straightforward, ", + 1, + "a", + 2, + "href", + "https://twitter.com/joelgrus", + 3, + "Joel Grus", + -1, + 3, + " has written a full ", + 1, + "a", + 2, + "href", + "https://fizzbuzzbook.com/", + 3, + "book", + -1, + 3, + " about different ways to program the game.\n ", + -1, + 1, + "p", + 3, + "\n A typical solution in Python will use ", + 1, + "code", + 3, + "if ... elif ... else", + -1, + 3, + " as follows:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "mod_3", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "%", + -1, + 1, + "span", + 3, + "3", + -1, + 1, + "span", + 3, + "mod_5", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "%", + -1, + 1, + "span", + 3, + "5", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "mod_3", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "and", + -1, + 1, + "span", + 3, + "mod_5", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"fizzbuzz\"", + -1, + 1, + "span", + 3, + "elif", + -1, + 1, + "span", + 3, + "mod_3", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"fizz\"", + -1, + 1, + "span", + 3, + "elif", + -1, + 1, + "span", + 3, + "mod_5", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"buzz\"", + -1, + 1, + "span", + 3, + "else", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-modulo-operator/", + 1, + "code", + 3, + "%", + -1, + 3, + " operator", + -1, + 3, + " calculates the modulus, which you can use to ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-modulo-operator/#python-modulo-operator-in-practice", + 3, + "test divisibility", + -1, + 3, + ". Namely, if ", + 1, + "em", + 3, + "a", + -1, + 3, + " modulus ", + 1, + "em", + 3, + "b", + -1, + 3, + " is 0 for two numbers ", + 1, + "em", + 3, + "a", + -1, + 3, + " and ", + 1, + "em", + 3, + "b", + -1, + 3, + ", then ", + 1, + "em", + 3, + "a", + -1, + 3, + " is divisible by ", + 1, + "em", + 3, + "b", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n In ", + 1, + "code", + 3, + "fizzbuzz()", + -1, + 3, + ", you calculate ", + 1, + "code", + 3, + "number % 3", + -1, + 3, + " and ", + 1, + "code", + 3, + "number % 5", + -1, + 3, + ", which you then use to test for divisibility with 3 and 5. Note that you must do the test for divisibility with both 3 and 5 first. If not, numbers that are divisible by both 3 and 5 will be covered by either the ", + 1, + "code", + 3, + "\"fizz\"", + -1, + 3, + " or the ", + 1, + "code", + 3, + "\"buzz\"", + -1, + 3, + " cases instead.\n ", + -1, + 1, + "p", + 3, + "\n You can check that your implementation gives the expected result:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "3", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "fizz", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "14", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "14", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "15", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "92", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "92", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "65", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "buzz", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You can confirm for yourself that 3 is divisible by 3, 65 is divisible by 5, and 15 is divisible by both 3 and 5, while 14 and 92 aren’t divisible by either 3 or 5.\n ", + -1, + 1, + "p", + 3, + "\n An ", + 1, + "code", + 3, + "if ... elif ... else", + -1, + 3, + " structure where you’re comparing one or a few variables several times over is quite straightforward to rewrite using pattern matching instead. For example, you can do the following:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "fizzbuzz", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "mod_3", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "%", + -1, + 1, + "span", + 3, + "3", + -1, + 1, + "span", + 3, + "mod_5", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + "%", + -1, + 1, + "span", + 3, + "5", + -1, + 1, + "span", + 3, + "match", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mod_3", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "mod_5", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"fizzbuzz\"", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"fizz\"", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "\"buzz\"", + -1, + 1, + "span", + 3, + "case", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "_", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "number", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You match on both ", + 1, + "code", + 3, + "mod_3", + -1, + 3, + " and ", + 1, + "code", + 3, + "mod_5", + -1, + 3, + ". Each ", + 1, + "code", + 3, + "case", + -1, + 3, + " pattern then matches either the literal number ", + 1, + "code", + 3, + "0", + -1, + 3, + " or the wildcard ", + 1, + "code", + 3, + "_", + -1, + 3, + " on the corresponding values.\n ", + -1, + 1, + "p", + 3, + "\n Compare and contrast this version with the previous one. Note how the pattern ", + 1, + "code", + 3, + "(0, 0)", + -1, + 3, + " corresponds to the test ", + 1, + "code", + 3, + "mod_3 == 0 and mod_5 == 0", + -1, + 3, + ", while ", + 1, + "code", + 3, + "(0, _)", + -1, + 3, + " corresponds to ", + 1, + "code", + 3, + "mod_3 == 0", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n As you saw earlier, you can use an OR pattern to match on several different patterns. For example, since ", + 1, + "code", + 3, + "mod_3", + -1, + 3, + " can only take the values ", + 1, + "code", + 3, + "0", + -1, + 3, + ", ", + 1, + "code", + 3, + "1", + -1, + 3, + ", and ", + 1, + "code", + 3, + "2", + -1, + 3, + ", you can replace ", + 1, + "code", + 3, + "case (_, 0)", + -1, + 3, + " with ", + 1, + "code", + 3, + "case (1, 0) | (2, 0)", + -1, + 3, + ". Remember that ", + 1, + "code", + 3, + "(0, 0)", + -1, + 3, + " has already been covered.\n ", + -1, + 1, + "p", + 3, + "\n The Python core developers have ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-3103/", + 3, + "consciously chosen", + -1, + 3, + " not to include ", + 1, + "code", + 3, + "switch ... case", + -1, + 3, + " statements in the language earlier. However, there are some third-party packages that do, like ", + 1, + "a", + 2, + "href", + "https://pypi.org/project/switchlang/", + 3, + "switchlang", + -1, + 3, + ", which adds a ", + 1, + "code", + 3, + "switch", + -1, + 3, + " command that also works on earlier versions of Python.\n ", + -3, + 1, + "section", + 1, + "h2", + 2, + "id", + "type-unions-aliases-and-guards", + 3, + "\n Type Unions, Aliases, and Guards", + 1, + "a", + 2, + "href", + "#type-unions-aliases-and-guards", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n Reliably, each new Python release brings some improvements to the ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/", + 3, + "static typing", + -1, + 3, + " system. Python 3.10 is no exception. In fact, four different PEPs about typing accompany this new release:\n ", + -1, + 1, + "ol", + 1, + "li", + 1, + "strong", + 3, + "PEP 604:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0604", + 3, + "Allow writing union types as ", + 1, + "code", + 3, + "X | Y", + -3, + 1, + "li", + 1, + "strong", + 3, + "PEP 613:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0613", + 3, + "Explicit Type Aliases", + -2, + 1, + "li", + 1, + "strong", + 3, + "PEP 647:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0647/", + 3, + "User-Defined Type Guards", + -2, + 1, + "li", + 1, + "strong", + 3, + "PEP 612:", + -1, + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0612/", + 3, + "Parameter Specification Variables", + -3, + 1, + "p", + 3, + "\n PEP 604 will probably be the most widely used of these changes going forward, but you’ll get a brief overview of each of the features in this section.\n ", + -1, + 1, + "p", + 3, + "\n You can use ", + 1, + "strong", + 3, + "union types", + -1, + 3, + " to declare that a variable can have one of several different types. For example, you’ve been able to type hint a function calculating the mean of a list of numbers, floats, or integers as follows:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "typing", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "List", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "Union", + -1, + 1, + "span", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "mean", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "List", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "Union", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "]])", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "sum", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "/", + -1, + 1, + "span", + 3, + "len", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The annotation ", + 1, + "code", + 3, + "List[Union[float, int]]", + -1, + 3, + " means that ", + 1, + "code", + 3, + "numbers", + -1, + 3, + " should be a list where each element is either a floating-point number or an integer. This works well, but the notation is a bit verbose. Also, you need to import both ", + 1, + "code", + 3, + "List", + -1, + 3, + " and ", + 1, + "code", + 3, + "Union", + -1, + 3, + " from ", + 1, + "code", + 3, + "typing", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, you can replace ", + 1, + "code", + 3, + "Union[float, int]", + -1, + 3, + " with the more succinct ", + 1, + "code", + 3, + "float | int", + -1, + 3, + ". Combine this with the ability to use ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-list/", + 1, + "code", + 3, + "list", + -2, + 3, + " instead of ", + 1, + "code", + 3, + "typing.List", + -1, + 3, + " in type hints, which ", + 1, + "a", + 2, + "href", + "https://realpython.com/python39-new-features/#type-hint-lists-and-dictionaries-directly", + 3, + "Python 3.9", + -1, + 3, + " introduced. You can then simplify your code while keeping all the type information:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "mean", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "sum", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "/", + -1, + 1, + "span", + 3, + "len", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The annotation of ", + 1, + "code", + 3, + "numbers", + -1, + 3, + " is easier to read now, and as an added bonus, you didn’t need to import anything from ", + 1, + "code", + 3, + "typing", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n A special case of union types is when a variable can have either a specific type or be ", + 1, + "code", + 3, + "None", + -1, + 3, + ". You can annotate such ", + 1, + "strong", + 3, + "optional types", + -1, + 3, + " either as ", + 1, + "code", + 3, + "Union[None, T]", + -1, + 3, + " or, equivalently, ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/#the-optional-type", + 1, + "code", + 3, + "Optional[T]", + -2, + 3, + " for some type ", + 1, + "code", + 3, + "T", + -1, + 3, + ". There is no new, special syntax for optional types, but you can use the new union syntax to avoid importing ", + 1, + "code", + 3, + "typing.Optional", + -1, + 3, + ":\n ", + -1, + 1, + "p", + 3, + "\n In this example, ", + 1, + "code", + 3, + "address", + -1, + 3, + " is allowed to be either ", + 1, + "code", + 3, + "None", + -1, + 3, + " or a string.\n ", + -1, + 1, + "p", + 3, + "\n You can also use the new union syntax at runtime in ", + 1, + "code", + 3, + "isinstance()", + -1, + 3, + " or ", + 1, + "code", + 3, + "issubclass()", + -1, + 3, + " tests:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "isinstance", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"mypy\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "True", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "issubclass", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "bytes", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "False", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Traditionally, you’ve used tuples to test for several types at once—for example, ", + 1, + "code", + 3, + "(str, int)", + -1, + 3, + " instead of ", + 1, + "code", + 3, + "str | int", + -1, + 3, + ". This old syntax will still work.\n ", + -1, + 1, + "p", + 1, + "strong", + 3, + "Type aliases", + -1, + 3, + " allow you to quickly ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/#type-aliases", + 3, + "define new aliases", + -1, + 3, + " that can stand in for more complicated type declarations. For example, say that you’re ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/#example-a-deck-of-cards", + 3, + "representing a playing card", + -1, + 3, + " using a tuple of suit and rank strings and a deck of cards by a list of such playing card tuples. A deck of cards is then type hinted as ", + 1, + "code", + 3, + "list[tuple[str, str]]", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n To simplify type annotation, you define type aliases as follows:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "tuple", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "Deck", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + "]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n This usually works okay. However, it’s often not possible for the type checker to know whether such a statement is a type alias or just the definition of a regular global variable. To help the type checker—or really, help the type checker help you—you can now explicitly annotate type aliases:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "typing", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "tuple", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "Deck", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + "]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Adding the ", + 1, + "code", + 3, + "TypeAlias", + -1, + 3, + " annotation clarifies the intention, both to a type checker and to anyone reading your code.\n ", + -1, + 1, + "p", + 1, + "strong", + 3, + "Type guards", + -1, + 3, + " are used to narrow down union types. The following function takes in either a string or ", + 1, + "code", + 3, + "None", + -1, + 3, + " but always returns a tuple of strings representing a playing card:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "get_ace", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "suit", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "None", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "tuple", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "]:", + -1, + 1, + "span", + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "suit", + -1, + 1, + "span", + 3, + "is", + -1, + 1, + "span", + 3, + "None", + -1, + 1, + "span", + 3, + ":", + -2, + 1, + "span", + 3, + "suit", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"♠\"", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "suit", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"A\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The highlighted line works as a type guard, and static type checkers are able to realize that ", + 1, + "code", + 3, + "suit", + -1, + 3, + " is necessarily a string when it’s returned.\n ", + -1, + 1, + "p", + 3, + "\n Currently, the type checkers can only use a ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0647/#motivation", + 3, + "few different constructs", + -1, + 3, + " to narrow down union types in this way. With the new ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/typing.html#typing.TypeGuard", + 1, + "code", + 3, + "typing.TypeGuard", + -2, + 3, + ", you can annotate custom functions that can be used to narrow down union types:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "typing", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "Any", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "TypeGuard", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "tuple", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "str", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "Deck", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "TypeAlias", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "is_deck_of_cards", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "obj", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Any", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "TypeGuard", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "Deck", + -1, + 1, + "span", + 3, + "]:", + -2, + 1, + "span", + 3, + "# Return True if obj is a deck of cards, otherwise False", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 1, + "code", + 3, + "is_deck_of_cards()", + -1, + 3, + " should return ", + 1, + "code", + 3, + "True", + -1, + 3, + " or ", + 1, + "code", + 3, + "False", + -1, + 3, + " depending on whether ", + 1, + "code", + 3, + "obj", + -1, + 3, + " represents a ", + 1, + "code", + 3, + "Deck", + -1, + 3, + " object or not. You can then use your guard function, and the type checker will be able to narrow down the types correctly:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "get_score", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "card_or_deck", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Card", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "Deck", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "is_deck_of_cards", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "card_or_deck", + -1, + 1, + "span", + 3, + "):", + -2, + 1, + "span", + 3, + "# Calculate score of a deck of cards", + -1, + 1, + "span", + 3, + "...", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Inside of the ", + 1, + "code", + 3, + "if", + -1, + 3, + " block, the type checker knows that ", + 1, + "code", + 3, + "card_or_deck", + -1, + 3, + " is, in fact, of the type ", + 1, + "code", + 3, + "Deck", + -1, + 3, + ". See ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0647/", + 3, + "PEP 647", + -1, + 3, + " for more details.\n ", + -1, + 1, + "p", + 3, + "\n The final new typing feature is ", + 1, + "strong", + 3, + "Parameter Specification Variables", + -1, + 3, + ", which is related to ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/#type-variables", + 3, + "type variables", + -1, + 3, + ". Consider the definition of a ", + 1, + "a", + 2, + "href", + "https://realpython.com/primer-on-python-decorators/", + 3, + "decorator", + -1, + 3, + ". In general, it looks something like the following:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "functools", + -1, + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "typing", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "Any", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "TypeVar", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "TypeVar", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"R\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "decorator", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "func", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "]:", + -2, + 1, + "span", + 3, + "@functools", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "wraps", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "func", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "wrapper", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "args", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Any", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "**", + -1, + 1, + "span", + 3, + "kwargs", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Any", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "wrapper", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The annotations mean that the function returned by the decorator is a callable with some parameters and the same return type, ", + 1, + "code", + 3, + "R", + -1, + 3, + ", as the function passed into the decorator. The ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-ellipsis/", + 3, + "ellipsis", + -1, + 3, + " (", + 1, + "code", + 3, + "...", + -1, + 3, + ") in the function header correctly allows any number of parameters, and each of those parameters can be of any type. However, there’s no validation that the returned callable has the same parameters as the function that was passed in. In practice, this means that type checkers aren’t able to check decorated functions properly.\n ", + -1, + 1, + "p", + 3, + "\n Unfortunately, you can’t use ", + 1, + "code", + 3, + "TypeVar", + -1, + 3, + " for the parameters because you don’t know how many parameters the function will have. In Python 3.10, you’ll have access to ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/typing.html#typing.ParamSpec", + 1, + "code", + 3, + "ParamSpec", + -2, + 3, + " in order to type hint these kinds of callables properly. ", + 1, + "code", + 3, + "ParamSpec", + -1, + 3, + " works similarly to ", + 1, + "code", + 3, + "TypeVar", + -1, + 3, + " but stands in for several parameters at once. You can rewrite your decorator as follows to take advantage of ", + 1, + "code", + 3, + "ParamSpec", + -1, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "functools", + -1, + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "typing", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "ParamSpec", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "TypeVar", + -1, + 1, + "span", + 3, + "P", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "ParamSpec", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"P\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "TypeVar", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"R\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "decorator", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "func", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "P", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "Callable", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "P", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + "]:", + -1, + 1, + "span", + 3, + "@functools", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "wraps", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "func", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "wrapper", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "args", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "P", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "args", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "**", + -1, + 1, + "span", + 3, + "kwargs", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "P", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "kwargs", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "R", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "wrapper", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that you also use ", + 1, + "code", + 3, + "P", + -1, + 3, + " when you annotate ", + 1, + "code", + 3, + "wrapper()", + -1, + 3, + ". You can also use the new ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/typing.html#typing.Concatenate", + 1, + "code", + 3, + "typing.Concatenate", + -2, + 3, + " to add types to ", + 1, + "code", + 3, + "ParamSpec", + -1, + 3, + ". See the ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/typing.html", + 3, + "documentation", + -1, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0612/", + 3, + "PEP 612", + -1, + 3, + " for details and examples.\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "stricter-zipping-of-sequences", + 3, + "\n Stricter Zipping of Sequences", + 1, + "a", + 2, + "href", + "#stricter-zipping-of-sequences", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 1, + "a", + 2, + "href", + "https://realpython.com/python-zip-function/", + 1, + "code", + 3, + "zip()", + -2, + 3, + " is a ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/functions.html#built-in-functions", + 3, + "built-in function", + -1, + 3, + " in Python that can combine elements from several sequences. Python 3.10 introduces the new ", + 1, + "code", + 3, + "strict", + -1, + 3, + " parameter, which adds a runtime test to check that all sequences being zipped have the same length.\n ", + -1, + 1, + "p", + 3, + "\n As an example, consider the following table of ", + 1, + "a", + 2, + "href", + "https://www.lego.com/", + 3, + "Lego", + -1, + 3, + " sets:\n ", + -1, + 1, + "p", + 3, + "\n One way to represent these data in plain Python would be with each column as a list. It could look something like this:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "\"Louvre\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"Diagon Alley\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"Saturn V\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"Millennium Falcon\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"NYC\"", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "\"21024\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"75978\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"92176\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"75192\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"21028\"", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "695", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "5544", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "1969", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "7541", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "598", + -1, + 1, + "span", + 3, + "]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that you have three independent lists, but there’s an implicit correspondence between their elements. The first name (", + 1, + "code", + 3, + "\"Louvre\"", + -1, + 3, + "), the first set number (", + 1, + "code", + 3, + "\"21024\"", + -1, + 3, + "), and the first number of pieces (", + 1, + "code", + 3, + "695", + -1, + 3, + ") all describe the first Lego set.\n ", + -1, + 1, + "p", + 1, + "code", + 3, + "zip()", + -1, + 3, + " can be used to iterate over these three lists in parallel:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "for", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "pieces", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "name", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + " (", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "num", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "): ", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "pieces", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + " pieces\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "Louvre (21024): 695 pieces", + -1, + 1, + "span", + 3, + "Diagon Alley (75978): 5544 pieces", + -1, + 1, + "span", + 3, + "Saturn V (92176): 1969 pieces", + -1, + 1, + "span", + 3, + "Millennium Falcon (75192): 7541 pieces", + -1, + 1, + "span", + 3, + "NYC (21028): 598 pieces", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note how each line collects information from all three lists and shows information about one particular set. This is a very common pattern that’s used in a lot of different Python code, including ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0618/#examples", + 3, + "in the standard library", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n You can also add ", + 1, + "code", + 3, + "list()", + -1, + 3, + " to collect the contents of all three lists in a single, nested list of tuples:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "[('Louvre', '21024', 695),", + -1, + 1, + "span", + 3, + " ('Diagon Alley', '75978', 5544),", + -1, + 1, + "span", + 3, + " ('Saturn V', '92176', 1969),", + -1, + 1, + "span", + 3, + " ('Millennium Falcon', '75192', 7541),", + -1, + 1, + "span", + 3, + " ('NYC', '21028', 598)]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note how the nested list closely resembles the original table.\n ", + -1, + 1, + "p", + 3, + "\n The dark side of using ", + 1, + "code", + 3, + "zip()", + -1, + 3, + " is that it’s quite easy to introduce a subtle bug that can be hard to discover. Note what happens if there’s a missing item in one of your lists:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "\"21024\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"75978\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"75192\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "\"21028\"", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "# Saturn V missing", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "[('Louvre', '21024', 695),", + -1, + 1, + "span", + 3, + " ('Diagon Alley', '75978', 5544),", + -1, + 1, + "span", + 3, + " ('Saturn V', '75192', 1969),", + -1, + 1, + "span", + 3, + " ('Millennium Falcon', '21028', 7541)]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n All the information about the New York City set disappeared! Additionally, the set numbers for Saturn V and Millennium Falcon are wrong. If your datasets are bigger, these kinds of errors can be very hard to discover. And even when you observe that something’s wrong, it’s not always easy to diagnose and fix.\n ", + -1, + 1, + "p", + 3, + "\n The issue is that you assumed that the three lists have the same number of elements and that the information is in the same order in each list. After ", + 1, + "code", + 3, + "set_numbers", + -1, + 3, + " gets corrupted, this assumption is no longer true.\n ", + -1, + 1, + "p", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0618/", + 3, + "PEP 618", + -1, + 3, + " introduces a new ", + 1, + "code", + 3, + "strict", + -1, + 3, + " keyword parameter to ", + 1, + "code", + 3, + "zip()", + -1, + 3, + " that you can use to confirm all sequences have the same length. In your example, it would raise an error alerting you to the corrupted list:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "strict", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "True", + -1, + 1, + "span", + 3, + "))", + -2, + 1, + "span", + 3, + "Traceback (most recent call last):", + -1, + 3, + "\n File ", + 1, + "span", + 3, + "\"", + 3, + "<", + 3, + "stdin", + 3, + ">", + 3, + "\"", + -1, + 3, + ", line ", + 1, + "span", + 3, + "1", + -1, + 3, + ", in ", + 1, + "span", + 3, + "<", + 3, + "module", + 3, + ">", + -1, + 1, + "span", + 3, + "ValueError", + -1, + 3, + ": ", + 1, + "span", + 3, + "zip() argument 2 is shorter than argument 1", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n When the iteration reaches the New York City Lego set, the second argument ", + 1, + "code", + 3, + "set_numbers", + -1, + 3, + " is already exhausted, while there are still elements left in the first argument ", + 1, + "code", + 3, + "names", + -1, + 3, + ". Instead of silently giving the wrong result, your code fails with an error, and you can take action to find and fix the mistake.\n ", + -1, + 1, + "p", + 3, + "\n There are use cases when you want to combine sequences of unequal length. Expand the box below to see how ", + 1, + "code", + 3, + "zip()", + -1, + 3, + " and ", + 1, + "code", + 3, + "itertools.zip_longest()", + -1, + 3, + " handle these:\n ", + -1, + 1, + "div", + 2, + "id", + "collapse_cardc07d76", + 2, + "data-parent", + "#collapse_cardc07d76", + 1, + "p", + 3, + "\n The ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-itertools/#what-is-itertools-and-why-should-you-use-it", + 3, + "following idiom", + -1, + 3, + " divides the Lego sets into pairs:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "num_per_group", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "2", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "iter", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ")]", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "num_per_group", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "[('Louvre', 'Diagon Alley'), ('Saturn V', 'Millennium Falcon')]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n There are five sets, a number that doesn’t divide evenly into pairs. In this case, the default behavior of ", + 1, + "code", + 3, + "zip()", + -1, + 3, + ", where the last element is dropped, might make sense. You could use ", + 1, + "code", + 3, + "strict=True", + -1, + 3, + " here as well, but that would raise an error when your list can’t be split into pairs. A third option, which could be the best in this case, is to use ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/itertools.html#itertools.zip_longest", + 1, + "code", + 3, + "zip_longest()", + -2, + 3, + " from the ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-itertools/", + 1, + "code", + 3, + "itertools", + -2, + 3, + " standard library.\n ", + -1, + 1, + "p", + 3, + "\n As the name suggests, ", + 1, + "code", + 3, + "zip_longest()", + -1, + 3, + " combines sequences until the longest sequence is exhausted. If you use ", + 1, + "code", + 3, + "zip_longest()", + -1, + 3, + " to divide the Lego sets, it becomes more explicit that New York City doesn’t have any pairing:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "itertools", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "zip_longest", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip_longest", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "iter", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ")]", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "num_per_group", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "fillvalue", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"\"", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "[('Louvre', 'Diagon Alley'),", + -1, + 1, + "span", + 3, + " ('Saturn V', 'Millennium Falcon'),", + -1, + 1, + "span", + 3, + " ('NYC', '')]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that ", + 1, + "code", + 3, + "'NYC'", + -1, + 3, + " shows up in the last tuple together with an empty string. You can control what’s filled in for missing values with the ", + 1, + "code", + 3, + "fillvalue", + -1, + 3, + " parameter.\n ", + -2, + 1, + "p", + 3, + "\n While ", + 1, + "code", + 3, + "strict", + -1, + 3, + " is not really adding any new functionality to ", + 1, + "code", + 3, + "zip()", + -1, + 3, + ", it can help you avoid those hard-to-find bugs.\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "new-functions-in-the-statistics-module", + 3, + "\n New Functions in the ", + 1, + "code", + 3, + "statistics", + -1, + 3, + " Module", + 1, + "a", + 2, + "href", + "#new-functions-in-the-statistics-module", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n The ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/statistics.html", + 1, + "code", + 3, + "statistics", + -2, + 3, + " module was added to the standard library all the way back in 2014 with the release of ", + 1, + "a", + 2, + "href", + "https://www.python.org/downloads/release/python-340/", + 3, + "Python 3.4", + -1, + 3, + ". The intent of ", + 1, + "code", + 3, + "statistics", + -1, + 3, + " is to make ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-statistics/", + 3, + "statistical calculations", + -1, + 3, + " at the ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0450/", + 3, + "level of graphing calculators", + -1, + 3, + " available in Python.\n ", + -1, + 1, + "p", + 3, + "\n Python 3.10 adds a few multivariable functions to ", + 1, + "code", + 3, + "statistics", + -1, + 3, + ":\n ", + -1, + 1, + "ul", + 1, + "li", + 1, + "strong", + 1, + "code", + 3, + "correlation()", + -2, + 3, + " to calculate Pearson’s ", + 1, + "a", + 2, + "href", + "https://realpython.com/numpy-scipy-pandas-correlation-python/", + 3, + "correlation", + -1, + 3, + " coefficient for two variables\n ", + -1, + 1, + "li", + 1, + "strong", + 1, + "code", + 3, + "covariance()", + -2, + 3, + " to calculate sample ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Covariance", + 3, + "covariance", + -1, + 3, + " for two variables\n ", + -1, + 1, + "li", + 1, + "strong", + 1, + "code", + 3, + "linear_regression()", + -2, + 3, + " to calculate the slope and intercept in a ", + 1, + "a", + 2, + "href", + "https://realpython.com/linear-regression-in-python/", + 3, + "linear regression", + -3, + 1, + "p", + 3, + "\n You can use each function to describe a certain aspect of the relationship between two variables. As an example, say that you have data from a set of blog posts—the number of words in each blog post and the number of views each post has had over some time period:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "7742", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "11539", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "16898", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "13447", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "4608", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "6628", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "2683", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "6156", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "2623", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "6948", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "8368", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "5901", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "3978", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "3329", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "2611", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "2096", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "1515", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "1177", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "814", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "467", + -1, + 1, + "span", + 3, + "]", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You now want to investigate whether there’s any (linear) relationship between the number of words and number of views. In Python 3.10, you can calculate the ", + 1, + "strong", + 3, + "correlation", + -1, + 3, + " between ", + 1, + "code", + 3, + "words", + -1, + 3, + " and ", + 1, + "code", + 3, + "views", + -1, + 3, + " with the new ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/statistics.html#statistics.correlation", + 1, + "code", + 3, + "correlation()", + -2, + 3, + " function:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "correlation", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "0.454180067865917", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The correlation between two variables is always a number between -1 and 1. If it’s close to 0, then there’s little correspondence between them, while a correlation close to -1 or 1 indicates that the behaviors of the two variables tend to follow each other. In this example, a correlation of 0.45 indicates that there’s a tendency for posts with more words to have more views, although it’s not a strong connection.\n ", + -1, + 1, + "p", + 3, + "\n You can also calculate the ", + 1, + "strong", + 3, + "covariance", + -1, + 3, + " between ", + 1, + "code", + 3, + "words", + -1, + 3, + " and ", + 1, + "code", + 3, + "views", + -1, + 3, + ". The covariance is another measure of the joint variability between two variables. You can calculate it with ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/statistics.html#statistics.covariance", + 1, + "code", + 3, + "covariance()", + -2, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "covariance", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "5292289.977777777", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n In contrast to correlation, covariance is an absolute measure. It should be interpreted in the context of the variability within the variables themselves. In fact, you can normalize the covariance by the ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Standard_deviation", + 3, + "standard deviation", + -1, + 3, + " of each variable to recover ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Pearson_correlation_coefficient", + 3, + "Pearson’s correlation coefficient", + -1, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "cov", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "covariance", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "σ_words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "σ_views", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "stdev", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + "),", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "stdev", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "cov", + -1, + 1, + "span", + 3, + "/", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "σ_words", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "σ_views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "0.454180067865917", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note that this matches your earlier correlation coefficient exactly.\n ", + -1, + 1, + "p", + 3, + "\n A third way of looking at the linear correspondence between the two variables is through ", + 1, + "strong", + 3, + "simple linear regression", + -1, + 3, + ". You do the ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/Simple_linear_regression", + 3, + "linear regression", + -1, + 3, + " by calculating two numbers, ", + 1, + "em", + 3, + "slope", + -1, + 3, + " and ", + 1, + "em", + 3, + "intercept", + -1, + 3, + ", so that the (squared) error is minimized in the approximation ", + 1, + "em", + 3, + "number of views", + -1, + 3, + " = ", + 1, + "em", + 3, + "slope", + -1, + 3, + " × ", + 1, + "em", + 3, + "number of words", + -1, + 3, + " + ", + 1, + "em", + 3, + "intercept", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, you can use ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/statistics.html#statistics.linear_regression", + 1, + "code", + 3, + "linear_regression()", + -2, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "linear_regression", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "LinearRegression(slope=0.2424443064354672, intercept=1103.6954940247645)", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Based on this regression, a post with 10,074 words could expect about 0.2424 × 10074 + 1104 = 3546 views. However, as you saw earlier, the correlation between the number of words and the number of views is quite weak. Therefore, you shouldn’t expect this prediction to be very accurate.\n ", + -1, + 1, + "p", + 3, + "\n The ", + 1, + "code", + 3, + "LinearRegression", + -1, + 3, + " object is a ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-namedtuple/", + 3, + "named tuple", + -1, + 3, + ". This means that you can unpack the slope and intercept directly:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "slope", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "intercept", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "statistics", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "linear_regression", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "words", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "views", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "slope", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "10074", + -1, + 1, + "span", + 3, + "+", + -1, + 1, + "span", + 3, + "intercept", + -1, + 1, + "span", + 3, + "3546.0794370556605", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Here, you use ", + 1, + "code", + 3, + "slope", + -1, + 3, + " and ", + 1, + "code", + 3, + "intercept", + -1, + 3, + " to predict the number of views on a blog post with 10,074 words.\n ", + -1, + 1, + "p", + 3, + "\n You still want to use some of the more advanced packages like pandas and statsmodels if you do a lot of statistical analysis. With the new additions to ", + 1, + "code", + 3, + "statistics", + -1, + 3, + " in Python 3.10, however, you have the chance to do basic analysis more easily without bringing in third-party dependencies.\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "other-pretty-cool-features", + 3, + "\n Other Pretty Cool Features", + 1, + "a", + 2, + "href", + "#other-pretty-cool-features", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n So far, you’ve seen the biggest and most impactful new features in Python 3.10. In this section, you’ll get a glimpse of a few of the other changes that the new version brings along. If you’re curious about all the changes made for this new version, check out the ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html", + 3, + "documentation", + -1, + 3, + ".\n ", + -1, + 1, + "section", + 1, + "h3", + 2, + "id", + "default-text-encodings", + 3, + "\n Default Text Encodings", + 1, + "a", + 2, + "href", + "#default-text-encodings", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n When you open a text file, the default encoding used to interpret the characters is system dependent. In particular, ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/locale.html#locale.getpreferredencoding", + 1, + "code", + 3, + "locale.getpreferredencoding()", + -2, + 3, + " is used. On Mac and Linux, this usually returns ", + 1, + "code", + 3, + "\"UTF-8\"", + -1, + 3, + ", while the result on Windows is more varied.\n ", + -1, + 1, + "p", + 3, + "\n You should therefore always specify an encoding when you attempt to open a text file:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "with", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"some_file.txt\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"r\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "encoding", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"utf-8\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "file", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + "# Do something with file", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n If you don’t explicitly specify an encoding, the preferred locale encoding is used, and you could experience that a file that can be read on one computer fails to open on another.\n ", + -1, + 1, + "p", + 3, + "\n Python 3.7 introduced ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/os.html#utf8-mode", + 3, + "UTF-8 mode", + -1, + 3, + ", which allows you to force your programs to use UTF-8 encoding independent of the locale encoding. You can enable UTF-8 mode by giving the ", + 1, + "code", + 3, + "-X utf8", + -1, + 3, + " command-line option to the ", + 1, + "code", + 3, + "python", + -1, + 3, + " executable or by setting the ", + 1, + "code", + 3, + "PYTHONUTF8", + -1, + 3, + " environment variable.\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, you can activate a warning that will tell you when a text file is opened without a specified encoding. Consider the following script, which doesn’t specify an encoding:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# mirror.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "pathlib", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "mirror_file", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 1, + "span", + 3, + "for", + -1, + 1, + "span", + 3, + "line", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "pathlib", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "Path", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"r\"", + -1, + 1, + "span", + 3, + "):", + -2, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "line", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "rstrip", + -1, + 1, + "span", + 3, + "()[::", + -1, + 1, + "span", + 3, + "-", + -1, + 1, + "span", + 3, + "1", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + ">", + 3, + "72", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "__name__", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "\"__main__\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "for", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "argv", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "1", + -1, + 1, + "span", + 3, + ":]:", + -1, + 1, + "span", + 3, + "mirror_file", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The program will echo one or more text files back to the console, but with each line reversed. Run the program on itself with the ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/io.html#io-encoding-warning", + 3, + "encoding warning", + -1, + 3, + " enabled:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "console", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "$ ", + -1, + 3, + "python", + 1, + "span", + -1, + 3, + "-X", + 1, + "span", + -1, + 3, + "warn_default_encoding", + 1, + "span", + -1, + 3, + "mirror.py", + 1, + "span", + -1, + 3, + "mirror.py\n", + 1, + "span", + 1, + "span", + 3, + "/home/rp/mirror.py:7: EncodingWarning: 'encoding' argument not specified", + -2, + 1, + "span", + 1, + "span", + 3, + " for line in pathlib.Path(filename).open(mode=\"r\"):", + -2, + 1, + "span", + 3, + " yp.rorrim #", + -1, + 1, + "span", + 3, + " bilhtap tropmi", + -1, + 1, + "span", + 3, + " sys tropmi", + -1, + 1, + "span", + 3, + " :)emanelif(elif_rorrim fed", + -1, + 1, + "span", + 3, + " :)\"r\"=edom(nepo.)emanelif(htaP.bilhtap ni enil rof", + -1, + 1, + "span", + 3, + " )\"}27", + 3, + ">", + 3, + ":]1-::[)(pirtsr.enil{\"f(tnirp", + -1, + 1, + "span", + 3, + " :\"__niam__\" == __eman__ fi", + -1, + 1, + "span", + 3, + " :]:1[vgra.sys ni emanelif rof", + -1, + 1, + "span", + 3, + " )emanelif(elif_rorrim", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Note the ", + 1, + "code", + 3, + "EncodingWarning", + -1, + 3, + " printed to the console. The command-line option ", + 1, + "code", + 3, + "-X warn_default_encoding", + -1, + 3, + " activates it. The warning will disappear if you specify an encoding—for example, ", + 1, + "code", + 3, + "encoding=\"utf-8\"", + -1, + 3, + "—when you open the file.\n ", + -1, + 1, + "p", + 3, + "\n There are times when you want to use the user-defined local encoding. You can still do so by explicitly using ", + 1, + "code", + 3, + "encoding=\"locale\"", + -1, + 3, + ". However, it’s recommended to use UTF-8 whenever possible. You can check out ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0597/", + 3, + "PEP 597", + -1, + 3, + " for more information.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "asynchronous-iteration", + 3, + "\n Asynchronous Iteration", + 1, + "a", + 2, + "href", + "#asynchronous-iteration", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 1, + "a", + 2, + "href", + "https://realpython.com/python-async-features/", + 3, + "Asynchronous programming", + -1, + 3, + " is a powerful programming paradigm that’s been available in Python ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0492/", + 3, + "since version 3.5", + -1, + 3, + ". You can recognize an asynchronous program by its use of the ", + 1, + "code", + 3, + "async", + -1, + 3, + " keyword or ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-classes/#special-methods-and-protocols", + 3, + "special methods", + -1, + 3, + " that ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0492/#why-magic-methods-start-with-a", + 3, + "start with ", + 1, + "code", + 3, + ".__a", + -2, + 3, + " like ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/reference/datamodel.html#object.__aiter__", + 1, + "code", + 3, + ".__aiter__()", + -2, + 3, + " or ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/reference/datamodel.html#object.__aenter__", + 1, + "code", + 3, + ".__aenter__()", + -2, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, two new asynchronous ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/functions.html#built-in-functions", + 3, + "built-in functions", + -1, + 3, + " are added: ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/functions.html#aiter", + 1, + "code", + 3, + "aiter()", + -2, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/functions.html#anext", + 1, + "code", + 3, + "anext()", + -2, + 3, + ". In practice, these functions call the ", + 1, + "code", + 3, + ".__aiter__()", + -1, + 3, + " and ", + 1, + "code", + 3, + ".__anext__()", + -1, + 3, + " special methods—analogous to the regular ", + 1, + "code", + 3, + "iter()", + -1, + 3, + " and ", + 1, + "code", + 3, + "next()", + -1, + 3, + "—so no new functionality is added. These are convenience functions that make your code more readable.\n ", + -1, + 1, + "p", + 3, + "\n In other words, in the newest version of Python, the following statements—where ", + 1, + "code", + 3, + "things", + -1, + 3, + " is an ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0492/#asynchronous-iterators-and-async-for", + 3, + "asynchronous iterable", + -1, + 3, + "—are equivalent:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "it", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "things", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "__aiter__", + -1, + 1, + "span", + 3, + "()", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "it", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "aiter", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "things", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n In either case, ", + 1, + "code", + 3, + "it", + -1, + 3, + " ends up as an asynchronous iterator. Expand the following box to see a complete example using ", + 1, + "code", + 3, + "aiter()", + -1, + 3, + " and ", + 1, + "code", + 3, + "anext()", + -1, + 3, + ":\n ", + -1, + 1, + "div", + 2, + "id", + "collapse_card7ba5eb", + 2, + "data-parent", + "#collapse_card7ba5eb", + 1, + "p", + 3, + "\n The following program counts the number of lines in several files. In practice, you use Python’s ability to iterate over files to count the number of lines. The script uses asynchronous iteration in order to handle several files concurrently.\n ", + -1, + 1, + "p", + 3, + "\n Note that you need to install the third-party ", + 1, + "a", + 2, + "href", + "https://pypi.org/project/aiofiles/", + 1, + "code", + 3, + "aiofiles", + -2, + 3, + " package with ", + 1, + "a", + 2, + "href", + "https://realpython.com/what-is-pip/", + 1, + "code", + 3, + "pip", + -2, + 3, + " before running this code:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# line_count.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "asyncio", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "aiofiles", + -1, + 1, + "span", + 3, + "async", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "count_lines", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"\"\"Count the number of lines in the given file\"\"\"", + -1, + 1, + "span", + 3, + "num_lines", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "0", + -1, + 1, + "span", + 3, + "async", + -1, + 1, + "span", + 3, + "with", + -1, + 1, + "span", + 3, + "aiofiles", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"r\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "file", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 1, + "span", + 3, + "lines", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "aiter", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "file", + -1, + 1, + "span", + 3, + ")", + -2, + 1, + "span", + 3, + "while", + -1, + 1, + "span", + 3, + "True", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "try", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 1, + "span", + 3, + "await", + -1, + 1, + "span", + 3, + "anext", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "lines", + -1, + 1, + "span", + 3, + ")", + -2, + 1, + "span", + 3, + "num_lines", + -1, + 1, + "span", + 3, + "+=", + -1, + 1, + "span", + 3, + "1", + -1, + 1, + "span", + 3, + "except", + -1, + 1, + "span", + 3, + "StopAsyncIteration", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "break", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "filename", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + ": ", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "num_lines", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "async", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "count_all_files", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filenames", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + -1, + 1, + "span", + 3, + "\"\"\"Asynchronously count lines in all files\"\"\"", + -1, + 1, + "span", + 3, + "tasks", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "asyncio", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "create_task", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "count_lines", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "))", + -1, + 1, + "span", + 3, + "for", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "filenames", + -1, + 1, + "span", + 3, + "]", + -1, + 1, + "span", + 3, + "await", + -1, + 1, + "span", + 3, + "asyncio", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "gather", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "*", + -1, + 1, + "span", + 3, + "tasks", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "__name__", + -1, + 1, + "span", + 3, + "==", + -1, + 1, + "span", + 3, + "\"__main__\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "asyncio", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "run", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "count_all_files", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "filenames", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "argv", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "1", + -1, + 1, + "span", + 3, + ":]))", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 1, + "code", + 3, + "asyncio", + -1, + 3, + " is used to create and run one asynchronous task per filename. ", + 1, + "code", + 3, + "count_lines()", + -1, + 3, + " opens one file asynchronously and iterates through it using ", + 1, + "code", + 3, + "aiter()", + -1, + 3, + " and ", + 1, + "code", + 3, + "anext()", + -1, + 3, + " in order to count the number of lines.\n ", + -2, + 1, + "p", + 3, + "\n See ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0525/", + 3, + "PEP 525", + -1, + 3, + " to learn more about asynchronous iteration.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "context-manager-syntax", + 3, + "\n Context Manager Syntax", + 1, + "a", + 2, + "href", + "#context-manager-syntax", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 1, + "a", + 2, + "href", + "https://realpython.com/python-with-statement/", + 3, + "Context managers", + -1, + 3, + " are great for managing resources in your programs. Until recently, though, their syntax has included an uncommon wart. You ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0617/#some-rules-are-not-actually-ll-1", + 3, + "haven’t been allowed", + -1, + 3, + " to use parentheses to break long ", + 1, + "code", + 3, + "with", + -1, + 3, + " statements like this:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "with", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "read_path", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"r\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "encoding", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"utf-8\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "read_file", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "write_path", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"w\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "encoding", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"utf-8\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "write_file", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "...", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n In earlier versions of Python, this causes an ", + 1, + "code", + 3, + "invalid syntax", + -1, + 3, + " error message. Instead, you need to use a backslash (", + 1, + "code", + 3, + "\\", + -1, + 3, + ") if you want to control where you break your lines:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "with", + -1, + 1, + "span", + 3, + "read_path", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"r\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "encoding", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"utf-8\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "read_file", + -1, + 1, + "span", + 3, + ",", + -1, + 3, + " \\\n ", + 1, + "span", + 3, + "write_path", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "open", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mode", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"w\"", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "encoding", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "\"utf-8\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "write_file", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "...", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n While ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-program-structure/#explicit-line-continuation", + 3, + "explicit line continuation", + -1, + 3, + " with backslashes is possible in Python, PEP 8 ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0008/#maximum-line-length", + 3, + "discourages it", + -1, + 3, + ". The ", + 1, + "a", + 2, + "href", + "https://black.readthedocs.io/", + 3, + "Black", + -1, + 3, + " formatting tool ", + 1, + "a", + 2, + "href", + "https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html", + 3, + "avoids", + -1, + 3, + " backslashes completely.\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, you’re now allowed to add parentheses around ", + 1, + "code", + 3, + "with", + -1, + 3, + " statements to your heart’s content. Especially if you’re employing several context managers at once, like in the example above, this can help improve the readability of your code. Python’s ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#parenthesized-context-managers", + 3, + "documentation", + -1, + 3, + " shows a few other possibilities with this new syntax.\n ", + -1, + 1, + "p", + 3, + "\n One small ", + 1, + "strong", + 3, + "fun fact", + -1, + 3, + ": parenthesized ", + 1, + "code", + 3, + "with", + -1, + 3, + " statements actually work in version 3.9 of ", + 1, + "a", + 2, + "href", + "https://realpython.com/cpython-source-code-guide/", + 3, + "CPython", + -1, + 3, + ". Their implementation came almost for free with the introduction of the ", + 1, + "a", + 2, + "href", + "https://realpython.com/python39-new-features/#a-more-powerful-python-parser", + 3, + "PEG parser", + -1, + 3, + " in ", + 1, + "a", + 2, + "href", + "https://realpython.com/python39-new-features/", + 3, + "Python 3.9", + -1, + 3, + ". The reason that this is called a Python 3.10 feature is that using the PEG parser is voluntary in Python 3.9, while Python 3.9, with the old LL(1) parser, doesn’t support parenthesized ", + 1, + "code", + 3, + "with", + -1, + 3, + " statements.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "modern-and-secure-ssl", + 3, + "\n Modern and Secure SSL", + 1, + "a", + 2, + "href", + "#modern-and-secure-ssl", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n Security can be challenging! A good rule of thumb is to avoid rolling your own security algorithms and instead rely on established packages.\n ", + -1, + 1, + "p", + 3, + "\n Python uses ", + 1, + "a", + 2, + "href", + "https://www.openssl.org/", + 3, + "OpenSSL", + -1, + 3, + " for different cryptographic features that are exposed in the ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/hashlib.html", + 1, + "code", + 3, + "hashlib", + -2, + 3, + ", ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/hmac.html", + 1, + "code", + 3, + "hmac", + -2, + 3, + ", and ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/ssl.html", + 1, + "code", + 3, + "ssl", + -2, + 3, + " standard library modules. Your system can manage OpenSSL, or a Python installer can include OpenSSL.\n ", + -1, + 1, + "p", + 3, + "\n Python 3.9 supports using any of the ", + 1, + "a", + 2, + "href", + "https://en.wikipedia.org/wiki/OpenSSL#Major_version_releases", + 3, + "OpenSSL versions", + -1, + 3, + " 1.0.2 LTS, 1.1.0, and 1.1.1 LTS. Both OpenSSL 1.0.2 LTS and OpenSSL 1.1.0 are past their lifetime, so Python 3.10 will only support OpenSSL 1.1.1 LTS, as described in the following table:\n ", + -1, + 1, + "div", + 1, + "table", + 1, + "thead", + 1, + "tr", + 1, + "th", + 3, + "\n Open SSL version\n ", + -1, + 1, + "th", + 3, + "\n Python 3.9\n ", + -1, + 1, + "th", + 3, + "\n Python 3.10\n ", + -1, + 1, + "th", + 3, + "\n End-of-life\n ", + -3, + 1, + "tbody", + 1, + "tr", + 1, + "td", + 3, + "\n 1.0.2 LTS\n ", + -1, + 1, + "td", + 3, + "\n ✔\n ", + -1, + 1, + "td", + 3, + "\n ✖\n ", + -2, + 1, + "tr", + 1, + "td", + 3, + "\n 1.1.0\n ", + -1, + 1, + "td", + 3, + "\n ✔\n ", + -1, + 1, + "td", + 3, + "\n ✖\n ", + -2, + 1, + "tr", + 1, + "td", + 3, + "\n 1.1.1 LTS\n ", + -1, + 1, + "td", + 3, + "\n ✔\n ", + -1, + 1, + "td", + 3, + "\n ✔\n ", + -5, + 1, + "p", + 3, + "\n This end of support for older versions will only affect you if you need to upgrade the system Python on an older operating system. If you use macOS or Windows, or if you install Python from ", + 1, + "a", + 2, + "href", + "https://www.python.org/", + 3, + "python.org", + -1, + 3, + " or use ", + 1, + "a", + 2, + "href", + "https://docs.conda.io/projects/conda/en/latest/user-guide/install/index.html", + 3, + "(Ana)Conda", + -1, + 3, + ", you’ll see no change.\n ", + -1, + 1, + "p", + 3, + "\n However, ", + 1, + "a", + 2, + "href", + "https://ubuntu.com/", + 3, + "Ubuntu", + -1, + 3, + " 18.04 LTS uses OpenSSL 1.1.0, while ", + 1, + "a", + 2, + "href", + "https://www.redhat.com/en/technologies/linux-platforms/enterprise-linux", + 3, + "Red Hat Enterprise Linux", + -1, + 3, + " (RHEL) 7 and ", + 1, + "a", + 2, + "href", + "https://www.centos.org/", + 3, + "CentOS", + -1, + 3, + " 7 both use OpenSSL 1.0.2 LTS. If you need to run Python 3.10 on these systems, you should look at installing it yourself using either the ", + 1, + "a", + 2, + "href", + "https://www.python.org/", + 3, + "python.org", + -1, + 3, + " or Conda installer.\n ", + -1, + 1, + "p", + 3, + "\n Dropping support for older versions of OpenSSL will make Python more secure. It’ll also help the Python developers in that code will be easier to maintain. Ultimately, this helps you because your Python experience will be more robust. See ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0644/", + 3, + "PEP 644", + -1, + 3, + " for more details.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "more-information-about-your-python-interpreter", + 3, + "\n More Information About Your Python Interpreter", + 1, + "a", + 2, + "href", + "#more-information-about-your-python-interpreter", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n The ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html", + 1, + "code", + 3, + "sys", + -2, + 3, + " module contains a lot of information about your system, the current Python runtime, and the script currently being executed. You can, for example, inquire about the paths where ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-import/#pythons-import-path", + 3, + "Python looks for modules", + -1, + 3, + " with ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html#sys.path", + 1, + "code", + 3, + "sys.path", + -2, + 3, + " and see all modules that ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-import/#import-internals", + 3, + "have been imported", + -1, + 3, + " in the current session with ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html#sys.modules", + 1, + "code", + 3, + "sys.modules", + -2, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n In Python 3.10, ", + 1, + "code", + 3, + "sys", + -1, + 3, + " has two new attributes. First, you can now get a list of the names of all modules in the standard library:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "len", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "stdlib_module_names", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "302", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "sorted", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "stdlib_module_names", + -1, + 1, + "span", + 3, + ")[", + -1, + 1, + "span", + 3, + "-", + -1, + 1, + "span", + 3, + "5", + -1, + 1, + "span", + 3, + ":]", + -1, + 1, + "span", + 3, + "['zipapp', 'zipfile', 'zipimport', 'zlib', 'zoneinfo']", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Here, you can see that there are around 300 modules in the standard library, several of which start with the letter ", + 1, + "code", + 3, + "z", + -1, + 3, + ". Note that only top-level modules and packages are listed. Subpackages like ", + 1, + "a", + 2, + "href", + "https://realpython.com/python38-new-features/#importlibmetadata", + 1, + "code", + 3, + "importlib.metadata", + -2, + 3, + " don’t get a separate entry.\n ", + -1, + 1, + "p", + 3, + "\n You will probably not be using ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/sys.html#sys.stdlib_module_names", + 1, + "code", + 3, + "sys.stdlib_module_names", + -2, + 3, + " all that often. Still, the list ties in nicely with similar introspection features like ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/keyword.html#keyword.kwlist", + 1, + "code", + 3, + "keyword.kwlist", + -2, + 3, + " and ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html#sys.builtin_module_names", + 1, + "code", + 3, + "sys.builtin_module_names", + -2, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n One possible use case for the new attribute is to identify which of the currently imported modules are third-party dependencies:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "pandas", + -1, + 1, + "span", + 3, + "as", + -1, + 1, + "span", + 3, + "pd", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "m", + -1, + 1, + "span", + 3, + "for", + -1, + 1, + "span", + 3, + "m", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "modules", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "\".\"", + -1, + 1, + "span", + 3, + "not", + -1, + 1, + "span", + 3, + "in", + -1, + 1, + "span", + 3, + "m", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "-", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "stdlib_module_names", + -1, + 1, + "span", + 3, + "{'__main__', 'numpy', '_cython_0_29_24', 'dateutil', 'pytz',", + -1, + 1, + "span", + 3, + " 'six', 'pandas', 'cython_runtime'}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n You find the imported top-level modules by looking at names in ", + 1, + "code", + 3, + "sys.modules", + -1, + 3, + " that don’t have a dot in their name. By comparing them to the standard library module names, you find that ", + 1, + "a", + 2, + "href", + "https://realpython.com/numpy-array-programming/", + 1, + "code", + 3, + "numpy", + -2, + 3, + ", ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-packages/#dateutil-for-working-with-dates-and-times", + 1, + "code", + 3, + "dateutil", + -2, + 3, + ", and ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-pandas-tricks/", + 1, + "code", + 3, + "pandas", + -2, + 3, + " are some of the imported third-party modules in this example.\n ", + -1, + 1, + "p", + 3, + "\n The other new attribute is ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/sys.html#sys.orig_argv", + 1, + "code", + 3, + "sys.orig_argv", + -2, + 3, + ". This is related to ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html#sys.argv", + 1, + "code", + 3, + "sys.argv", + -2, + 3, + ", which holds the ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-command-line-arguments/#the-sysargv-array", + 3, + "command-line arguments", + -1, + 3, + " given to your program when it was started. In contrast, ", + 1, + "code", + 3, + "sys.orig_argv", + -1, + 3, + " lists the command-line arguments passed to the ", + 1, + "code", + 3, + "python", + -1, + 3, + " executable itself. Consider the following example:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# argvs.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"argv: ", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "argv", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "print", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "f", + -1, + 1, + "span", + 3, + "\"orig_argv: ", + -1, + 1, + "span", + 3, + "{", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "orig_argv", + -1, + 1, + "span", + 3, + "}", + -1, + 1, + "span", + 3, + "\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n This script echoes back the ", + 1, + "code", + 3, + "orig_argv", + -1, + 3, + " and ", + 1, + "code", + 3, + "argv", + -1, + 3, + " lists. Run it to see how the information is captured:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "console", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "$ ", + -1, + 3, + "python", + 1, + "span", + -1, + 3, + "-X", + 1, + "span", + -1, + 3, + "utf8", + 1, + "span", + -1, + 3, + "-O", + 1, + "span", + -1, + 3, + "argvs.py", + 1, + "span", + -1, + 1, + "span", + 3, + "3", + -1, + 3, + ".10", + 1, + "span", + -1, + 3, + "--upgrade\n", + 1, + "span", + 3, + "argv: ['argvs.py', '3.10', '--upgrade']", + -1, + 1, + "span", + 3, + "orig_argv: ['python', '-X', 'utf8', '-O', 'argvs.py', '3.10', '--upgrade']", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Essentially, all arguments—including the name of the Python executable—end up in ", + 1, + "code", + 3, + "orig_argv", + -1, + 3, + ". This is in contrast to ", + 1, + "code", + 3, + "argv", + -1, + 3, + ", which only contains the arguments that aren’t handled by ", + 1, + "code", + 3, + "python", + -1, + 3, + " itself.\n ", + -1, + 1, + "p", + 3, + "\n Again, this is not a feature that you’ll use a lot. If your program needs to concern itself with how it’s being run, you’re usually better off relying on information that’s already exposed instead of trying to parse this list. For example, you can choose to use the ", + 1, + "a", + 2, + "href", + "#stricter-zipping-of-sequences", + 3, + "strict ", + 1, + "code", + 3, + "zip()", + -1, + 3, + " mode", + -1, + 3, + " only when your script is not running with the optimized flag, ", + 1, + "code", + 3, + "-O", + -1, + 3, + ", like this:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "zip", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "names", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "set_numbers", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "num_pieces", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "strict", + -1, + 1, + "span", + 3, + "=", + -1, + 1, + "span", + 3, + "__debug__", + -1, + 1, + "span", + 3, + "))", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/constants.html#__debug__", + 1, + "code", + 3, + "__debug__", + -2, + 3, + " flag is set when the interpreter starts. It’ll be ", + 1, + "code", + 3, + "False", + -1, + 3, + " if you’re running ", + 1, + "code", + 3, + "python", + -1, + 3, + " with ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/using/cmdline.html#cmdoption-o", + 1, + "code", + 3, + "-O", + -2, + 3, + " or ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/using/cmdline.html#cmdoption-oo", + 1, + "code", + 3, + "-OO", + -2, + 3, + " specified, and ", + 1, + "code", + 3, + "True", + -1, + 3, + " otherwise. Using ", + 1, + "code", + 3, + "__debug__", + -1, + 3, + " is usually preferable to ", + 1, + "code", + 3, + "\"-O\" not in sys.orig_argv", + -1, + 3, + " or some similar construct.\n ", + -1, + 1, + "p", + 3, + "\n One of the ", + 1, + "a", + 2, + "href", + "https://bugs.python.org/issue23427#msg371028", + 3, + "motivating use cases", + -1, + 3, + " for ", + 1, + "code", + 3, + "sys.orig_argv", + -1, + 3, + " is that you can use it to spawn a new Python process with the same or modified command-line arguments as your current process.\n ", + -2, + 1, + "section", + 1, + "h3", + 2, + "id", + "future-annotations", + 3, + "\n Future Annotations", + 1, + "a", + 2, + "href", + "#future-annotations", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 1, + "a", + 2, + "href", + "https://realpython.com/python-type-checking/#annotations", + 3, + "Annotations", + -1, + 3, + " were introduced in Python 3 to give you a way to attach metadata to variables, function parameters, and return values. They are most commonly used to add type hints to your code.\n ", + -1, + 1, + "p", + 3, + "\n One challenge with annotations is that they must be valid Python code. For one thing, this makes it ", + 1, + "a", + 2, + "href", + "https://realpython.com/python37-new-features/#typing-enhancements", + 3, + "hard to type hint", + -1, + 3, + " recursive classes. ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0563/", + 3, + "PEP 563", + -1, + 3, + " introduced ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-news-april-2021/#pep-563-pep-649-and-the-future-of-python-type-annotations", + 3, + "postponed evaluation of annotations", + -1, + 3, + ", making it possible to annotate with names that haven’t yet been defined. Since Python 3.7, you can activate postponed evaluation of annotations with a ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/__future__.html", + 1, + "code", + 3, + "__future__", + -2, + 3, + " import:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "from", + -1, + 1, + "span", + 3, + "__future__", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "annotations", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n The intention was that postponed evaluation would become the default at some point in the future. After the ", + 1, + "a", + 2, + "href", + "https://pyfound.blogspot.com/2020/04/the-2020-python-language-summit.html", + 3, + "2020 Python Language Summit", + -1, + 3, + ", it was decided to make this happen in Python 3.10.\n ", + -1, + 1, + "p", + 3, + "\n However, after more testing, it became clear that postponed evaluation didn’t work well for projects that use annotations at runtime. Key people in the ", + 1, + "a", + 2, + "href", + "https://realpython.com/fastapi-python-web-apis/", + 3, + "FastAPI", + -1, + 3, + " and the ", + 1, + "a", + 2, + "href", + "https://pydantic-docs.helpmanual.io/", + 3, + "Pydantic", + -1, + 3, + " projects ", + 1, + "a", + 2, + "href", + "https://dev.to/tiangolo/the-future-of-fastapi-and-pydantic-is-bright-3pbm", + 3, + "voiced their concerns", + -1, + 3, + ". At the last minute, it was decided to reschedule these changes for Python 3.11.\n ", + -1, + 1, + "p", + 3, + "\n To ease the transition into future behavior, a few changes have been made in Python 3.10 as well. Most importantly, a new ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/library/inspect.html#inspect.get_annotations", + 1, + "code", + 3, + "inspect.get_annotations()", + -2, + 3, + " function has been added. You should call this to access annotations at runtime:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "pycon", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "inspect", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "def", + -1, + 1, + "span", + 3, + "mean", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "list", + -1, + 1, + "span", + 3, + "[", + -1, + 1, + "span", + 3, + "int", + -1, + 1, + "span", + 3, + "|", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + "])", + -1, + 1, + "span", + 3, + "-", + 3, + ">", + -1, + 1, + "span", + 3, + "float", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "... ", + -1, + 1, + "span", + 3, + "return", + -1, + 1, + "span", + 3, + "sum", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "/", + -1, + 1, + "span", + 3, + "len", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "numbers", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "...", + -1, + 1, + "span", + 3, + ">", + 3, + ">", + 3, + ">", + -1, + 1, + "span", + 3, + "inspect", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "get_annotations", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "mean", + -1, + 1, + "span", + 3, + ")", + -1, + 1, + "span", + 3, + "{'numbers': list[int | float], 'return': ", + 3, + "<", + 3, + "class 'float'", + 3, + ">", + 3, + "}", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n Check out ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/howto/annotations.html", + 3, + "Annotations Best Practices", + -1, + 3, + " for details.\n ", + -3, + 1, + "section", + 1, + "h2", + 2, + "id", + "how-to-detect-python-310-at-runtime", + 3, + "\n How to Detect Python 3.10 at Runtime", + 1, + "a", + 2, + "href", + "#how-to-detect-python-310-at-runtime", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n Python 3.10 is the first version of Python with a two-digit minor version number. While this is mostly an interesting fun fact and an indication that Python 3 has been around for quite some time, it does also have some practical consequences.\n ", + -1, + 1, + "p", + 3, + "\n When your code needs to do something specific based on the version of Python at runtime, you’ve gotten away with doing a ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/reference/expressions.html#value-comparisons", + 3, + "lexicographical", + -1, + 3, + " comparison of version strings until now. While it’s never been good practice, it’s been possible to do the following:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# bad_version_check.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + "# Don't do the following", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "version", + -1, + 1, + "span", + 3, + "<", + -1, + 1, + "span", + 3, + "\"3.6\"", + -1, + 1, + "span", + 3, + ":", + -1, + 1, + "span", + 3, + "raise", + -1, + 1, + "span", + 3, + "SystemExit", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Only Python 3.6 and above is supported\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n In Python 3.10, this code will raise ", + 1, + "code", + 3, + "SystemExit", + -1, + 3, + " and stop your program. This happens because, as strings, ", + 1, + "code", + 3, + "\"3.10\"", + -1, + 3, + " is less than ", + 1, + "code", + 3, + "\"3.6\"", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n The correct way to compare version numbers is to use tuples of numbers:\n ", + -1, + 1, + "div", + 2, + "data-syntax-language", + "python", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "# good_version_check.py", + -1, + 1, + "span", + 3, + "import", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + "if", + -1, + 1, + "span", + 3, + "sys", + -1, + 1, + "span", + 3, + ".", + -1, + 1, + "span", + 3, + "version_info", + -1, + 1, + "span", + 3, + "<", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "3", + -1, + 1, + "span", + 3, + ",", + -1, + 1, + "span", + 3, + "6", + -1, + 1, + "span", + 3, + "):", + -1, + 1, + "span", + 3, + "raise", + -1, + 1, + "span", + 3, + "SystemExit", + -1, + 1, + "span", + 3, + "(", + -1, + 1, + "span", + 3, + "\"Only Python 3.6 and above is supported\"", + -1, + 1, + "span", + 3, + ")", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 1, + "a", + 2, + "href", + "https://docs.python.org/3/library/sys.html#sys.version_info", + 1, + "code", + 3, + "sys.version_info", + -2, + 3, + " is a tuple object you can use for comparisons.\n ", + -1, + 1, + "p", + 3, + "\n If you’re doing these kinds of comparisons in your code, you should check your code with ", + 1, + "a", + 2, + "href", + "https://pypi.org/project/flake8-2020/", + 3, + "flake8-2020", + -1, + 3, + " to make sure you’re handling versions correctly:\n ", + -1, + 1, + "div", + 2, + "data-is-repl", + "true", + 2, + "data-syntax-language", + "console", + 2, + "aria-label", + "Code block", + 1, + "div", + 1, + "pre", + 1, + "code", + 1, + "span", + 3, + "$ ", + -1, + 3, + "python", + 1, + "span", + -1, + 3, + "-m", + 1, + "span", + -1, + 3, + "pip", + 1, + "span", + -1, + 3, + "install", + 1, + "span", + -1, + 3, + "flake8-2020\n\n", + 1, + "span", + 3, + "$ ", + -1, + 3, + "flake8", + 1, + "span", + -1, + 3, + "bad_version_check.py", + 1, + "span", + -1, + 3, + "good_version_check.py\n", + 1, + "span", + 3, + "bad_version_check.py:3:4: YTT103 `sys.version` compared to string", + -1, + 1, + "span", + 3, + " (python3.10), use `sys.version_info`", + -4, + 1, + "template", + 1, + "span", + 3, + "Copied!", + -3, + 1, + "p", + 3, + "\n With the ", + 1, + "code", + 3, + "flake8-2020", + -1, + 3, + " extension activated, you’ll get a recommendation about replacing ", + 1, + "code", + 3, + "sys.version", + -1, + 3, + " with ", + 1, + "code", + 3, + "sys.version_info", + -1, + 3, + ".\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "so-should-you-upgrade-to-python-310", + 3, + "\n So, Should You Upgrade to Python 3.10?", + 1, + "a", + 2, + "href", + "#so-should-you-upgrade-to-python-310", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n You’ve now seen the coolest features of the newest and latest version of Python. The question now is whether you should upgrade to Python 3.10, and if yes, when you should do so. There are two different aspects to consider when thinking about upgrading to Python 3.10:\n ", + -1, + 1, + "ol", + 1, + "li", + 3, + "Should you upgrade your environment so that you ", + 1, + "strong", + 3, + "run your code", + -1, + 3, + " with the Python 3.10 interpreter?\n ", + -1, + 1, + "li", + 3, + "Should you ", + 1, + "strong", + 3, + "write your code", + -1, + 3, + " using the new Python 3.10 features?\n ", + -2, + 1, + "p", + 3, + "\n Clearly, if you want to test out structural pattern matching or any of the other cool new features you’ve read about here, you need Python 3.10. It’s possible to install the latest version side by side with your current Python version. A straightforward way to do this is to use an environment manager like ", + 1, + "a", + 2, + "href", + "https://realpython.com/intro-to-pyenv/", + 3, + "pyenv", + -1, + 3, + " or ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-windows-machine-learning-setup/", + 3, + "Conda", + -1, + 3, + ". You can also ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-versions-docker/", + 3, + "use Docker", + -1, + 3, + " to run Python 3.10 without installing it locally.\n ", + -1, + 1, + "p", + 3, + "\n Python 3.10 has been through about five months of beta testing, so there shouldn’t be any big issues with starting to use it for your own development. You may find that some of your dependencies don’t immediately have ", + 1, + "a", + 2, + "href", + "https://realpython.com/python-wheels/", + 3, + "wheels for Python 3.10", + -1, + 3, + " available, which makes them more cumbersome to install. But in general, using the newest Python for local development is fairly safe.\n ", + -1, + 1, + "p", + 3, + "\n As always, you should be careful before upgrading your production environment. Be vigilant about testing that your code runs well on the new version. In particular, you want to be on the lookout for features that are ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#deprecated", + 3, + "deprecated", + -1, + 3, + " or ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#removed", + 3, + "removed", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n Whether you can start using the new features in your code or not depends on your user base and the environment where your code is running. If you can guarantee that Python 3.10 is available, then there’s no danger in using the new union type syntax or any other new feature.\n ", + -1, + 1, + "p", + 3, + "\n If you’re distributing an app or a library that’s used by others instead, you may want to be a bit more conservative. Currently, ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0494", + 3, + "Python 3.6", + -1, + 3, + " is the oldest officially supported Python version. It reaches end-of-life in December 2021, after which ", + 1, + "a", + 2, + "href", + "https://www.python.org/dev/peps/pep-0537", + 3, + "Python 3.7", + -1, + 3, + " will be the minimum supported version.\n ", + -1, + 1, + "p", + 3, + "\n The documentation includes a useful guide about ", + 1, + "a", + 2, + "href", + "https://docs.python.org/3.10/whatsnew/3.10.html#porting-to-python-3-10", + 3, + "porting your code to Python 3.10", + -1, + 3, + ". Check it out for more details!\n ", + -2, + 1, + "section", + 1, + "h2", + 2, + "id", + "conclusion", + 3, + "\n Conclusion", + 1, + "a", + 2, + "href", + "#conclusion", + 2, + "title", + "Permanent link", + -2, + 1, + "p", + 3, + "\n The release of a new Python version is always worth celebrating. Even if you can’t start using the new features right away, they’ll become broadly available and part of your daily life within a few years.\n ", + -1, + 1, + "p", + 1, + "strong", + 3, + "In this tutorial, you’ve seen new features like:", + -2, + 1, + "ul", + 1, + "li", + 3, + "Friendlier ", + 1, + "strong", + 3, + "error messages", + -2, + 1, + "li", + 3, + "Powerful ", + 1, + "strong", + 3, + "structural pattern matching", + -2, + 1, + "li", + 1, + "strong", + 3, + "Type hint", + -1, + 3, + " improvements\n ", + -1, + 1, + "li", + 3, + "Safer ", + 1, + "strong", + 3, + "combination of sequences", + -2, + 1, + "li", + 3, + "New ", + 1, + "strong", + 3, + "statistics functions", + -3, + 1, + "p", + 3, + "\n For more Python 3.10 tips and a discussion with members of the ", + 1, + "em", + 3, + "Real Python", + -1, + 3, + " team, check out ", + 1, + "a", + 2, + "href", + "https://realpython.com/podcasts/rpp/81/", + 3, + "Real Python Podcast Episode #81", + -1, + 3, + ".\n ", + -1, + 1, + "p", + 3, + "\n Have fun trying out the new features! Share your experiences in the comments below.\n ", + -2, + 1, + "p", + 1, + "span", + 3, + " Watch Now", + -1, + 3, + " This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: ", + 1, + "a", + 2, + "href", + "http://fakehost/courses/cool-new-features-python-310/", + 1, + "strong", + 3, + "Cool New Features in Python 3.10", + -4, + 1, + "div", + 1, + "p", + 3, + "\n Get a short ", + 3, + "&", + 3, + " sweet ", + 1, + "strong", + 3, + "Python Trick", + -1, + 3, + " delivered to your inbox every couple of days. No spam ever. Unsubscribe any time. 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    +
    +
    + Python 3.10: Cool New Features for You to Try +
    +
    +

    + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    +

    + Python 3.10 is out! Volunteers have been working on the new version since May 2020 to bring you a better, faster, and more secure Python. As of October 4, 2021, the first official version is available. +

    +

    Each new version of Python brings a host of changes. You can read about all of them in the documentation. Here, you’ll get to learn about the coolest new features.

    +

    + In this tutorial, you’ll learn about: +

    +
      +
    • Debugging with more helpful and precise error messages +
      • +
    • Using structural pattern matching to work with data structures
      • +
    • Adding more readable and more specific type hints +
      • +
    • Checking the length of sequences when using zip() +
      • +
    • Calculating multivariable statistics +
      • +
    +

    To try out the new features yourself, you need to run Python 3.10. You can get it from the Python homepage. Alternatively, you can use Docker with the latest Python image.

    +
    +

    Better Error Messages +

    +

    Python is often lauded for being a user-friendly programming language. While this is true, there are certain parts of Python that could be friendlier. Python 3.10 comes with a host of more precise and constructive error messages. In this section, you’ll see some of the newest improvements. The full list is available in the documentation.

    +

    Think back to writing your first Hello World program in Python:

    +
    +
    + 
    # hello.py
+
+print("Hello, World!)
+
    +
    +
    +

    Maybe you created a file, added the famous call to print(), and saved it as hello.py. You then ran the program, eager to call yourself a proper Pythonista. However, something went wrong:

    +
    +
    + 
    $ python hello.py
+  File "/home/rp/hello.py", line 3
+    print("Hello, World!)
+                        ^
+SyntaxError: EOL while scanning string literal
+
    +
    +
    +

    There was a SyntaxError in the code. EOL, what does that even mean? You went back to your code, and after a bit of staring and searching, you realized that there was a missing quotation mark at the end of your string.

    +

    One of the more impactful improvements in Python 3.10 is better and more precise error messages for many common issues. If you run your buggy Hello World in Python 3.10, you’ll get a bit more help than in earlier versions of Python:

    +
    +
    + 
    $ python hello.py
+  File "/home/rp/hello.py", line 3
+    print("Hello, World!)
+          ^
+SyntaxError: unterminated string literal (detected at line 3)
+
    +
    +
    +

    The error message is still a bit technical, but gone is the mysterious EOL. Instead, the message tells you that you need to terminate your string! There are similar improvements to many different error messages, as you’ll see below.

    +

    A SyntaxError is an error raised when your code is parsed, before it even starts to execute. Syntax errors can be tricky to debug because the interpreter provides imprecise or sometimes even misleading error messages. The following code is missing a curly brace to terminate the dictionary:

    +
    +
    + 
     1# unterminated_dict.py
+ 2
+ 3months = {
+ 4    10: "October",
+ 5    11: "November",
+ 6    12: "December"
+ 7
+ 8print(f"{months[10]} is the tenth month")
+
    +
    +
    +

    The missing closing curly brace that should have been on line 7 is an error. If you run this code with Python 3.9 or earlier, you’ll see the following error message:

    +
    +
    + 
      File "/home/rp/unterminated_dict.py", line 8
+    print(f"{months[10]} is the tenth month")
+    ^
+SyntaxError: invalid syntax
+
    +
    +
    +

    The error message highlights line 8, but there are no syntactical problems in line 8! If you’ve experienced your share of syntax errors in Python, you might already know that the trick is to look at the lines before the one Python complains about. In this case, you’re looking for the missing closing brace on line 7.

    +

    In Python 3.10, the same code shows a much more helpful and precise error message:

    +
    +
    + 
      File "/home/rp/unterminated_dict.py", line 3
+    months = {
+             ^
+SyntaxError: '{' was never closed
+
    +
    +
    +

    This points you straight to the offending dictionary and allows you to fix the issue in no time.

    +

    There are a few other ways to mess up dictionary syntax. A typical one is forgetting a comma after one of the items:

    +
    +
    + 
     1# missing_comma.py
+ 2
+ 3months = {
+ 4    10: "October"
+ 5    11: "November",
+ 6    12: "December",
+ 7}
+
    +
    +
    +

    In this code, a comma is missing at the end of line 4. Python 3.10 gives you a clear suggestion on how to fix your code:

    +
    +
    + 
      File "/home/real_python/missing_comma.py", line 4
+    10: "October"
+        ^^^^^^^^^
+SyntaxError: invalid syntax. Perhaps you forgot a comma?
+
    +
    +
    +

    You can add the missing comma and have your code back up and running in no time.

    +

    Another common mistake is using the assignment operator (=) instead of the equality comparison operator (==) when you’re comparing values. Previously, this would just cause another invalid syntax message. In the newest version of Python, you get some more advice:

    +
    +
    + 
    >>> if month = "October":
+  File "<stdin>", line 1
+    if month = "October":
+       ^^^^^^^^^^^^^^^^^
+SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?
+
    +
    +
    +

    The parser suggests that you maybe meant to use a comparison operator or an assignment expression operator instead.

    +

    Take note of another nifty improvement in Python 3.10 error messages. The last two examples show how carets (^^^) highlight the whole offending expression. Previously, a single caret symbol (^) indicated just an approximate location.

    +

    The final error message improvement that you’ll play with for now is that attribute and name errors can now offer suggestions if you misspell an attribute or a name:

    +
    +
    + 
    >>> import math
+>>> math.py
+AttributeError: module 'math' has no attribute 'py'. Did you mean: 'pi'?
+
+>>> pint
+NameError: name 'pint' is not defined. Did you mean: 'print'?
+
+>>> release = "3.10"
+>>> relaese
+NameError: name 'relaese' is not defined. Did you mean: 'release'?
+
    +
    +
    +

    Note that the suggestions work for both built-in names and names that you define yourself, although they may not be available in all environments. If you like these kinds of suggestions, check out BetterErrorMessages, which offers similar suggestions in even more contexts.

    +

    The improvements you’ve seen in this section are just some of the many error messages that have gotten a face-lift. The new Python will be even more user-friendly than before, and hopefully, the new error messages will save you both time and frustration going forward.

    +
    +
    +

    Structural Pattern Matching +

    +

    The biggest new feature in Python 3.10, probably both in terms of controversy and potential impact, is structural pattern matching. Its introduction has sometimes been referred to as switch ... case coming to Python, but you’ll see that structural pattern matching is much more powerful than that.

    +

    You’ll see three different examples that together highlight why this feature is called structural pattern matching and show you how you can use this new feature:

    +
      +
    1. Detecting and deconstructing different structures in your data
      2. +
    2. Using different kinds of patterns +
      3. +
    3. + Matching literal patterns +
      4. +
    +

    Structural pattern matching is a comprehensive addition to the Python language. To give you a taste of how you can take advantage of it in your own projects, the next three subsections will dive into some of the details. You’ll also see some links that can help you explore in even more depth if you want.

    +
    +

    Deconstructing Data Structures +

    +

    At its core, structural pattern matching is about defining patterns to which your data structures can be matched. In this section, you’ll study a practical example where you’ll work with data that are structured differently, even though the meaning is the same. You’ll define several patterns, and depending on which pattern matches your data, you’ll process your data appropriately.

    +

    This section will be a bit light on explanations of the possible patterns. Instead, it will try to give you an impression of the possibilities. The next section will step back and explain the patterns in more detail.

    +

    Time to match your first pattern! The following example uses a match ... case block to find the first name of a user by extracting it from a user data structure:

    +
    +
    + 
    >>> user = {
+...     "name": {"first": "Pablo", "last": "Galindo Salgado"},
+...     "title": "Python 3.10 release manager",
+... }
+
+>>> match user:
+...     case {"name": {"first": first_name}}:
+...         pass
+...
+
+>>> first_name
+'Pablo'
+
    +
    +
    +

    You can see structural pattern matching at work in the highlighted lines. user is a small dictionary with user information. The case line specifies a pattern that user is matched against. In this case, you’re looking for a dictionary with a "name" key whose value is a new dictionary. This nested dictionary has a key called "first". The corresponding value is bound to the variable first_name.

    +

    For a practical example, say that you’re processing user data where the underlying data model changes over time. Therefore, you need to be able to process different versions of the same data.

    +

    In the next example, you’ll use data from randomuser.me. This is a great API for generating random user data that you can use during testing and development. The API is also an example of an API that has changed over time. You can still access the old versions of the API.

    +

    You may expand the collapsed section below to see how you can use requests to obtain different versions of the user data using the API:

    +
    +

    You can get a random user from the API using requests as follows:

    +
    +
    + 
    # random_user.py
+
+import requests
+
+def get_user(version="1.3"):
+    """Get random users"""
+    url = f"https://randomuser.me/api/{version}/?results=1"
+    response = requests.get(url)
+    if response:
+        return response.json()["results"][0]
+
    +
    +
    +

    + get_user() gets one random user in JSON format. Note the version parameter. The structure of the returned data has changed quite a bit between earlier versions like "1.1" and the current version "1.3", but in each case, the actual user data are contained in a list inside the "results" array. The function returns the first—and only—user in this list. +

    +

    At the time of writing, the latest version of the API is 1.3 and the data has the following structure:

    +
    +
    + 
    {
+    "gender": "female",
+    "name": {
+        "title": "Miss",
+        "first": "Ilona",
+        "last": "Jokela"
+    },
+    "location": {
+        "street": {
+            "number": 4473,
+            "name": "Mannerheimintie"
+        },
+        "city": "Harjavalta",
+        "state": "Ostrobothnia",
+        "country": "Finland",
+        "postcode": 44879,
+        "coordinates": {
+            "latitude": "-6.0321",
+            "longitude": "123.2213"
+        },
+        "timezone": {
+            "offset": "+5:30",
+            "description": "Bombay, Calcutta, Madras, New Delhi"
+        }
+    },
+    "email": "ilona.jokela@example.com",
+    "login": {
+        "uuid": "632b7617-6312-4edf-9c24-d6334a6af52d",
+        "username": "brownsnake482",
+        "password": "biatch",
+        "salt": "ofk518ZW",
+        "md5": "6d589615ca44f6e583c85d45bf431c54",
+        "sha1": "cd87c931d579bdff77af96c09e0eea82d1edfc19",
+        "sha256": "6038ede83d4ce74116faa67fb3b1b2e6f6898e5749b57b5a0312bd46a539214a"
+    },
+    "dob": {
+        "age": 64
+    },
+    "registered": {
+        "date": ,
+        "age": 15
+    },
+    "phone": "07-369-318",
+    "cell": "048-284-01-59",
+    "id": {
+        "name": "HETU",
+        "value": "NaNNA204undefined"
+    },
+    "picture": {
+        "large": "https://randomuser.me/api/portraits/women/28.jpg",
+        "medium": "https://randomuser.me/api/portraits/med/women/28.jpg",
+        "thumbnail": "https://randomuser.me/api/portraits/thumb/women/28.jpg"
+    },
+    "nat": "FI"
+}
+
    +
    +
    +

    One of the members that changed between different versions is "dob", the date of birth. Note that in version 1.3, this is a JSON object with two members, "date" and "age".

    +

    Compare the result above with a version 1.1 random user:

    +
    +
    + 
    {
+    "gender": "female",
+    "name": {
+        "title": "miss",
+        "first": "ilona",
+        "last": "jokela"
+    },
+    "location": {
+        "street": "7336 myllypuronkatu",
+        "city": "kurikka",
+        "state": "central ostrobothnia",
+        "postcode": 53740
+    },
+    "email": "ilona.jokela@example.com",
+    "login": {
+        "username": "blackelephant837",
+        "password": "sand",
+        "salt": "yofk518Z",
+        "md5": "b26367ea967600d679ee3e0b9bda012f",
+        "sha1": "87d2910595acba5b8e8aa8b00a841bab08580e2f",
+        "sha256": "73bd0d205d0dc83ae184ae222ff2e9de5ea4039119a962c4f97fabd5bbfa7aca"
+    },
+    "registered": ,
+    "phone": "04-636-931",
+    "cell": "048-828-40-15",
+    "id": {
+        "name": "HETU",
+        "value": "366-9204"
+    },
+    "picture": {
+        "large": "https://randomuser.me/api/portraits/women/24.jpg",
+        "medium": "https://randomuser.me/api/portraits/med/women/24.jpg",
+        "thumbnail": "https://randomuser.me/api/portraits/thumb/women/24.jpg"
+    },
+    "nat": "FI"
+}
+
    +
    +
    +

    Observe that in this older format, the value of the "dob" member is a plain string.

    +
    +

    In this example, you’ll work with the information about the date of birth (dob) for each user. The structure of these data has changed between different versions of the Random User API:

    +
    +
    + 
    # Version 1.1
+"dob": 
+
+# Version 1.3
+"dob": {"date": , "age": 64}
+
    +
    +
    +

    Note that in version 1.1, the date of birth is represented as a simple string, while in version 1.3, it’s a JSON object with two members: "date" and "age". Say that you want to find the age of a user. Depending on the structure of your data, you’d either need to calculate the age based on the date of birth or look up the age if it’s already available.

    +

    Traditionally, you would detect the structure of the data with an if test, maybe based on the type of the "dob" field. You can approach this differently in Python 3.10. Now, you can use structural pattern matching instead:

    +
    +
    + 
     1# random_user.py (continued)
+ 2
+ 3from datetime import datetime
+ 4
+ 5def get_age(user):
+ 6    """Get the age of a user"""
+ 7    match user:
+ 8        case {"dob": {"age": int(age)}}:
+ 9            return age
+10        case {"dob": dob}:
+11            now = datetime.now()
+12            dob_date = datetime.strptime(dob, "%Y-%m-%d %H:%M:%S")
+13            return now.year - dob_date.year
+
    +
    +
    +

    The match ... case construct is new in Python 3.10 and is how you perform structural pattern matching. You start with a match statement that specifies what you want to match. In this example, that’s the user data structure.

    +

    One or several case statements follow match. Each case describes one pattern, and the indented block beneath it says what should happen if there’s a match. In this example:

    +
      +
    • +

      + Line 8 matches a dictionary with a "dob" key whose value is another dictionary with an integer (int) item named "age". The name age captures its value. +

      +
      • +
    • +

      + Line 10 matches any dictionary with a "dob" key. The name dob captures its value. +

      +
      • +
    +

    One important feature of pattern matching is that at most one pattern will be matched. Since the pattern on line 10 matches any dictionary with "dob", it’s important that the more specific pattern on line 8 comes first.

    +

    Before looking closer at the details of the patterns and how they work, try calling get_age() with different data structures to see the result:

    +
    +
    + 
    >>> import random_user
+
+>>> users11 = random_user.get_user(version="1.1")
+>>> random_user.get_age(users11)
+55
+
+>>> users13 = random_user.get_user(version="1.3")
+>>> random_user.get_age(users13)
+64
+
    +
    +
    +

    Your code can calculate the age correctly for both versions of the user data, which have different dates of birth.

    +

    Look closer at those patterns. The first pattern, {"dob": {"age": int(age)}}, matches version 1.3 of the user data:

    +
    +
    + 
    {
+    ...
+    "dob": {"date": , "age": 64},
+    ...
+}
+
    +
    +
    +

    The first pattern is a nested pattern. The outer curly braces say that a dictionary with the key "dob" is required. The corresponding value should be a dictionary. This nested dictionary must match the subpattern {"age": int(age)}. In other words, it needs to have an "age" key with an integer value. That value is bound to the name age.

    +

    The second pattern, {"dob": dob}, matches the older version 1.1 of the user data:

    +

    This second pattern is a simpler pattern than the first one. Again, the curly braces indicate that it will match a dictionary. However, any dictionary with a "dob" key is matched because there are no other restrictions specified. The value of that key is bound to the name dob.

    +

    The main takeaway is that you can describe the structure of your data using mostly familiar notation. One striking change, though, is that you can use names like dob and age, which aren’t yet defined. Instead, values from your data are bound to these names when a pattern matches.

    +

    You’ve explored some of the power of structural pattern matching in this example. In the next section, you’ll dive a bit more into the details.

    +
    +
    +

    Using Different Kinds of Patterns +

    +

    You’ve seen an example of how you can use patterns to effectively unravel complicated data structures. Now, you’ll take a step back and look at the building blocks that make up this new feature. Many things come together to make it work. In fact, there are three Python Enhancement Proposals (PEPs) that describe structural pattern matching:

    +
      +
    1. + PEP 634: Specification +
      2. +
    2. + PEP 635: Motivation and Rationale +
      3. +
    3. + PEP 636: Tutorial +
      4. +
    +

    These documents give you a lot of background and detail if you’re interested in a deeper dive than what follows.

    +

    Patterns are at the center of structural pattern matching. In this section, you’ll learn about some of the different kinds of patterns that exist:

    +
      +
    • + Mapping patterns match mapping structures like dictionaries. +
      • +
    • + Sequence patterns match sequence structures like tuples and lists. +
      • +
    • + Capture patterns bind values to names. +
      • +
    • + AS patterns bind the value of subpatterns to names. +
      • +
    • + OR patterns match one of several different subpatterns. +
      • +
    • + Wildcard patterns match anything. +
      • +
    • + Class patterns match class structures. +
      • +
    • + Value patterns match values stored in attributes. +
      • +
    • + Literal patterns match literal values. +
      • +
    +

    You already used several of them in the example in the previous section. In particular, you used mapping patterns to unravel data stored in dictionaries. In this section, you’ll learn more about how some of these work. All the details are available in the PEPs mentioned above.

    +

    A capture pattern is used to capture a match to a pattern and bind it to a name. Consider the following recursive function that sums a list of numbers:

    +
    +
    + 
     1def sum_list(numbers):
+ 2    match numbers:
+ 3        case []:
+ 4            return 0
+ 5        case [first, *rest]:
+ 6            return first + sum_list(rest)
+
    +
    +
    +

    The first case on line 3 matches the empty list and returns 0 as its sum. The second case on line 5 uses a sequence pattern with two capture patterns to match lists with one or more elements. The first element in the list is captured and bound to the name first. The second capture pattern, *rest, uses unpacking syntax to match any number of elements. rest will bind to a list containing all elements of numbers except the first one.

    +

    + sum_list() calculates the sum of a list of numbers by recursively adding the first number in the list and the sum of the rest of the numbers. You can use it as follows: +

    +
    +
    + 
    >>> sum_list([4, 5, 9, 4])
+22
+
    +
    +
    +

    The sum of 4 + 5 + 9 + 4 is correctly calculated to be 22. As an exercise for yourself, you can try to trace the recursive calls to sum_list() to make sure you understand how the code sums the whole list.

    +

    + sum_list() handles summing up a list of numbers. Observe what happens if you try to sum anything that isn’t a list: +

    +
    +
    + 
    >>> print(sum_list("4594"))
+None
+
+>>> print(sum_list(4594))
+None
+
    +
    +
    +

    Passing a string or a number to sum_list() returns None. This occurs because none of the patterns match, and the execution continues after the match block. That happens to be the end of the function, so sum_list() implicitly returns None.

    +

    Often, though, you want to be alerted about failed matches. You can add a catchall pattern as the final case that handles this by raising an error, for example. You can use the underscore (_) as a wildcard pattern that matches anything without binding it to a name. You can add some error handling to sum_list() as follows:

    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [first, *rest]:
+            return first + sum_list(rest)
+        case _:
+            wrong_type = numbers.__class__.__name__
+            raise ValueError(f"Can only sum lists, not {wrong_type!r}")
+
    +
    +
    +

    The final case will match anything that doesn’t match the first two patterns. This will raise a descriptive error, for instance, if you try to calculate sum_list(4594). This is useful when you need to alert your users that some input was not matched as expected.

    +

    Your patterns are still not foolproof, though. Consider what happens if you try to sum a list of strings:

    +
    +
    + 
    >>> sum_list(["45", "94"])
+TypeError: can only concatenate str (not "int") to str
+
    +
    +
    +

    The base case returns 0, so therefore the summing only works for types that you can add with numbers. Python doesn’t know how to add numbers and text strings together. You can restrict your pattern to only match integers using a class pattern:

    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [int(first), *rest]:
+            return first + sum_list(rest)
+        case _:
+            raise ValueError(f"Can only sum lists of numbers")
+
    +
    +
    +

    Adding int() around first makes sure that the pattern only matches if the value is an integer. This might be too restrictive, though. Your function should be able to sum both integers and floating-point numbers, so how can you allow this in your pattern?

    +

    To check whether at least one out of several subpatterns match, you can use an OR pattern. OR patterns consist of two or more subpatterns, and the pattern matches if at least one of the subpatterns does. You can use this to match when the first element is either of type int or type float:

    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [int(first) | float(first), *rest]:
+            return first + sum_list(rest)
+        case _:
+            raise ValueError(f"Can only sum lists of numbers")
+
    +
    +
    +

    You use the pipe symbol (|) to separate the subpatterns in an OR pattern. Your function now allows summing a list of floating-point numbers:

    +
    +
    + 
    >>> sum_list([45.94, 46.17, 46.72])
+138.82999999999998
+
    +
    +
    +

    There’s a lot of power and flexibility within structural pattern matching, even more than what you’ve seen so far. Some things that aren’t covered in this overview are:

    + +

    If you’re interested, have a look in the documentation to learn more about these features as well. In the next section, you’ll learn about literal patterns and value patterns.

    +
    +
    +

    Matching Literal Patterns +

    +

    A literal pattern is a pattern that matches a literal object like an explicit string or number. In a sense, this is the most basic kind of pattern and allows you to emulate switch ... case statements seen in other languages. The following example matches a specific name:

    +
    +
    + 
    def greet(name):
+    match name:
+        case "Guido":
+            print("Hi, Guido!")
+        case _:
+            print("Howdy, stranger!")
+
    +
    +
    +

    The first case matches the literal string "Guido". In this case, you use _ as a wildcard to print a generic greeting whenever name is not "Guido". Such literal patterns can sometimes take the place of if ... elif ... else constructs and can play the same role that switch ... case does in some other languages.

    +

    One limitation with structural pattern matching is that you can’t directly match values stored in variables. Say that you’ve defined bdfl = "Guido". A pattern like case bdfl: will not match "Guido". Instead, this will be interpreted as a capture pattern that matches anything and binds that value to bdfl, effectively overwriting the old value.

    +

    You can, however, use a value pattern to match stored values. A value pattern looks a bit like a capture pattern but uses a previously defined dotted name that holds the value that will be matched against.

    +

    You can, for example, use an enumeration to create such dotted names:

    +
    +
    + 
    import enum
+
+class Pythonista(str, enum.Enum):
+    BDFL = "Guido"
+    FLUFL = "Barry"
+
+def greet(name):
+    match name:
+        case Pythonista.BDFL:
+            print("Hi, Guido!")
+        case _:
+            print("Howdy, stranger!")
+
    +
    +
    +

    The first case now uses a value pattern to match Pythonista.BDFL, which is "Guido". Note that you can use any dotted name in a value pattern. You could, for example, have used a regular class or a module instead of the enumeration.

    +

    To see a bigger example of how to use literal patterns, consider the game of FizzBuzz. This is a counting game where you should replace some numbers with words according to the following rules:

    +
      +
    • You replace numbers divisible by 3 with fizz.
      • +
    • You replace numbers divisible by 5 with buzz.
      • +
    • You replace numbers divisible by both 3 and 5 with fizzbuzz.
      • +
    +

    FizzBuzz is sometimes used to introduce conditionals in programming education and as a screening problem in interviews. Even though a solution is quite straightforward, Joel Grus has written a full book about different ways to program the game.

    +

    A typical solution in Python will use if ... elif ... else as follows:

    +
    +
    + 
    def fizzbuzz(number):
+    mod_3 = number % 3
+    mod_5 = number % 5
+
+    if mod_3 == 0 and mod_5 == 0:
+        return "fizzbuzz"
+    elif mod_3 == 0:
+        return "fizz"
+    elif mod_5 == 0:
+        return "buzz"
+    else:
+        return str(number)
+
    +
    +
    +

    The % operator calculates the modulus, which you can use to test divisibility. Namely, if a modulus b is 0 for two numbers a and b, then a is divisible by b.

    +

    In fizzbuzz(), you calculate number % 3 and number % 5, which you then use to test for divisibility with 3 and 5. Note that you must do the test for divisibility with both 3 and 5 first. If not, numbers that are divisible by both 3 and 5 will be covered by either the "fizz" or the "buzz" cases instead.

    +

    You can check that your implementation gives the expected result:

    +
    +
    + 
    >>> fizzbuzz(3)
+fizz
+
+>>> fizzbuzz(14)
+14
+
+>>> fizzbuzz(15)
+fizzbuzz
+
+>>> fizzbuzz(92)
+92
+
+>>> fizzbuzz(65)
+buzz
+
    +
    +
    +

    You can confirm for yourself that 3 is divisible by 3, 65 is divisible by 5, and 15 is divisible by both 3 and 5, while 14 and 92 aren’t divisible by either 3 or 5.

    +

    An if ... elif ... else structure where you’re comparing one or a few variables several times over is quite straightforward to rewrite using pattern matching instead. For example, you can do the following:

    +
    +
    + 
    def fizzbuzz(number):
+    mod_3 = number % 3
+    mod_5 = number % 5
+
+    match (mod_3, mod_5):
+        case (0, 0):
+            return "fizzbuzz"
+        case (0, _):
+            return "fizz"
+        case (_, 0):
+            return "buzz"
+        case _:
+            return str(number)
+
    +
    +
    +

    You match on both mod_3 and mod_5. Each case pattern then matches either the literal number 0 or the wildcard _ on the corresponding values.

    +

    Compare and contrast this version with the previous one. Note how the pattern (0, 0) corresponds to the test mod_3 == 0 and mod_5 == 0, while (0, _) corresponds to mod_3 == 0.

    +

    As you saw earlier, you can use an OR pattern to match on several different patterns. For example, since mod_3 can only take the values 0, 1, and 2, you can replace case (_, 0) with case (1, 0) | (2, 0). Remember that (0, 0) has already been covered.

    +

    The Python core developers have consciously chosen not to include switch ... case statements in the language earlier. However, there are some third-party packages that do, like switchlang, which adds a switch command that also works on earlier versions of Python.

    +
    +
    +
    +

    Type Unions, Aliases, and Guards +

    +

    Reliably, each new Python release brings some improvements to the static typing system. Python 3.10 is no exception. In fact, four different PEPs about typing accompany this new release:

    +
      +
    1. + PEP 604: Allow writing union types as X | Y +
      2. +
    2. + PEP 613: Explicit Type Aliases +
      3. +
    3. + PEP 647: User-Defined Type Guards +
      4. +
    4. + PEP 612: Parameter Specification Variables +
      5. +
    +

    PEP 604 will probably be the most widely used of these changes going forward, but you’ll get a brief overview of each of the features in this section.

    +

    You can use union types to declare that a variable can have one of several different types. For example, you’ve been able to type hint a function calculating the mean of a list of numbers, floats, or integers as follows:

    +
    +
    + 
    from typing import List, Union
+
+def mean(numbers: List[Union[float, int]]) -> float:
+    return sum(numbers) / len(numbers)
+
    +
    +
    +

    The annotation List[Union[float, int]] means that numbers should be a list where each element is either a floating-point number or an integer. This works well, but the notation is a bit verbose. Also, you need to import both List and Union from typing.

    +

    In Python 3.10, you can replace Union[float, int] with the more succinct float | int. Combine this with the ability to use list instead of typing.List in type hints, which Python 3.9 introduced. You can then simplify your code while keeping all the type information:

    +
    +
    + 
    def mean(numbers: list[float | int]) -> float:
+    return sum(numbers) / len(numbers)
+
    +
    +
    +

    The annotation of numbers is easier to read now, and as an added bonus, you didn’t need to import anything from typing.

    +

    A special case of union types is when a variable can have either a specific type or be None. You can annotate such optional types either as Union[None, T] or, equivalently, Optional[T] for some type T. There is no new, special syntax for optional types, but you can use the new union syntax to avoid importing typing.Optional:

    +

    In this example, address is allowed to be either None or a string.

    +

    You can also use the new union syntax at runtime in isinstance() or issubclass() tests:

    +
    +
    + 
    >>> isinstance("mypy", str | int)
+True
+
+>>> issubclass(str, int | float | bytes)
+False
+
    +
    +
    +

    Traditionally, you’ve used tuples to test for several types at once—for example, (str, int) instead of str | int. This old syntax will still work.

    +

    + Type aliases allow you to quickly define new aliases that can stand in for more complicated type declarations. For example, say that you’re representing a playing card using a tuple of suit and rank strings and a deck of cards by a list of such playing card tuples. A deck of cards is then type hinted as list[tuple[str, str]]. +

    +

    To simplify type annotation, you define type aliases as follows:

    +
    +
    + 
    Card = tuple[str, str]
+Deck = list[Card]
+
    +
    +
    +

    This usually works okay. However, it’s often not possible for the type checker to know whether such a statement is a type alias or just the definition of a regular global variable. To help the type checker—or really, help the type checker help you—you can now explicitly annotate type aliases:

    +
    +
    + 
    from typing import TypeAlias
+
+Card: TypeAlias = tuple[str, str]
+Deck: TypeAlias = list[Card]
+
    +
    +
    +

    Adding the TypeAlias annotation clarifies the intention, both to a type checker and to anyone reading your code.

    +

    + Type guards are used to narrow down union types. The following function takes in either a string or None but always returns a tuple of strings representing a playing card: +

    +
    +
    + 
    def get_ace(suit: str | None) -> tuple[str, str]:
+    if suit is None:
+        suit = "♠"
+    return (suit, "A")
+
    +
    +
    +

    The highlighted line works as a type guard, and static type checkers are able to realize that suit is necessarily a string when it’s returned.

    +

    Currently, the type checkers can only use a few different constructs to narrow down union types in this way. With the new typing.TypeGuard, you can annotate custom functions that can be used to narrow down union types:

    +
    +
    + 
    from typing import Any, TypeAlias, TypeGuard
+
+Card: TypeAlias = tuple[str, str]
+Deck: TypeAlias = list[Card]
+
+def is_deck_of_cards(obj: Any) -> TypeGuard[Deck]:
+    # Return True if obj is a deck of cards, otherwise False
+
    +
    +
    +

    + is_deck_of_cards() should return True or False depending on whether obj represents a Deck object or not. You can then use your guard function, and the type checker will be able to narrow down the types correctly: +

    +
    +
    + 
    def get_score(card_or_deck: Card | Deck) -> int:
+    if is_deck_of_cards(card_or_deck):
+        # Calculate score of a deck of cards
+    ...
+
    +
    +
    +

    Inside of the if block, the type checker knows that card_or_deck is, in fact, of the type Deck. See PEP 647 for more details.

    +

    The final new typing feature is Parameter Specification Variables, which is related to type variables. Consider the definition of a decorator. In general, it looks something like the following:

    +
    +
    + 
    import functools
+from typing import Any, Callable, TypeVar
+
+R = TypeVar("R")
+
+def decorator(func: Callable[..., R]) -> Callable[..., R]:
+    @functools.wraps(func)
+    def wrapper(*args: Any, **kwargs: Any) -> R:
+        ...
+    return wrapper
+
    +
    +
    +

    The annotations mean that the function returned by the decorator is a callable with some parameters and the same return type, R, as the function passed into the decorator. The ellipsis (...) in the function header correctly allows any number of parameters, and each of those parameters can be of any type. However, there’s no validation that the returned callable has the same parameters as the function that was passed in. In practice, this means that type checkers aren’t able to check decorated functions properly.

    +

    Unfortunately, you can’t use TypeVar for the parameters because you don’t know how many parameters the function will have. In Python 3.10, you’ll have access to ParamSpec in order to type hint these kinds of callables properly. ParamSpec works similarly to TypeVar but stands in for several parameters at once. You can rewrite your decorator as follows to take advantage of ParamSpec:

    +
    +
    + 
    import functools
+from typing import Callable, ParamSpec, TypeVar
+
+P = ParamSpec("P")
+R = TypeVar("R")
+
+def decorator(func: Callable[P, R]) -> Callable[P, R]:
+    @functools.wraps(func)
+    def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
+        ...
+    return wrapper
+
    +
    +
    +

    Note that you also use P when you annotate wrapper(). You can also use the new typing.Concatenate to add types to ParamSpec. See the documentation and PEP 612 for details and examples.

    +
    +
    +

    Stricter Zipping of Sequences +

    +

    + zip() is a built-in function in Python that can combine elements from several sequences. Python 3.10 introduces the new strict parameter, which adds a runtime test to check that all sequences being zipped have the same length. +

    +

    As an example, consider the following table of Lego sets:

    +

    One way to represent these data in plain Python would be with each column as a list. It could look something like this:

    +
    +
    + 
    >>> names = ["Louvre", "Diagon Alley", "Saturn V", "Millennium Falcon", "NYC"]
+>>> set_numbers = ["21024", "75978", "92176", "75192", "21028"]
+>>> num_pieces = [695, 5544, 1969, 7541, 598]
+
    +
    +
    +

    Note that you have three independent lists, but there’s an implicit correspondence between their elements. The first name ("Louvre"), the first set number ("21024"), and the first number of pieces (695) all describe the first Lego set.

    +

    + zip() can be used to iterate over these three lists in parallel: +

    +
    +
    + 
    >>> for name, num, pieces in zip(names, set_numbers, num_pieces):
+...     print(f"{name} ({num}): {pieces} pieces")
+...
+Louvre (21024): 695 pieces
+Diagon Alley (75978): 5544 pieces
+Saturn V (92176): 1969 pieces
+Millennium Falcon (75192): 7541 pieces
+NYC (21028): 598 pieces
+
    +
    +
    +

    Note how each line collects information from all three lists and shows information about one particular set. This is a very common pattern that’s used in a lot of different Python code, including in the standard library.

    +

    You can also add list() to collect the contents of all three lists in a single, nested list of tuples:

    +
    +
    + 
    >>> list(zip(names, set_numbers, num_pieces))
+[('Louvre', '21024', 695),
+ ('Diagon Alley', '75978', 5544),
+ ('Saturn V', '92176', 1969),
+ ('Millennium Falcon', '75192', 7541),
+ ('NYC', '21028', 598)]
+
    +
    +
    +

    Note how the nested list closely resembles the original table.

    +

    The dark side of using zip() is that it’s quite easy to introduce a subtle bug that can be hard to discover. Note what happens if there’s a missing item in one of your lists:

    +
    +
    + 
    >>> set_numbers = ["21024", "75978", "75192", "21028"]  # Saturn V missing
+
+>>> list(zip(names, set_numbers, num_pieces))
+[('Louvre', '21024', 695),
+ ('Diagon Alley', '75978', 5544),
+ ('Saturn V', '75192', 1969),
+ ('Millennium Falcon', '21028', 7541)]
+
    +
    +
    +

    All the information about the New York City set disappeared! Additionally, the set numbers for Saturn V and Millennium Falcon are wrong. If your datasets are bigger, these kinds of errors can be very hard to discover. And even when you observe that something’s wrong, it’s not always easy to diagnose and fix.

    +

    The issue is that you assumed that the three lists have the same number of elements and that the information is in the same order in each list. After set_numbers gets corrupted, this assumption is no longer true.

    +

    + PEP 618 introduces a new strict keyword parameter to zip() that you can use to confirm all sequences have the same length. In your example, it would raise an error alerting you to the corrupted list: +

    +
    +
    + 
    >>> list(zip(names, set_numbers, num_pieces, strict=True))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+ValueError: zip() argument 2 is shorter than argument 1
+
    +
    +
    +

    When the iteration reaches the New York City Lego set, the second argument set_numbers is already exhausted, while there are still elements left in the first argument names. Instead of silently giving the wrong result, your code fails with an error, and you can take action to find and fix the mistake.

    +

    There are use cases when you want to combine sequences of unequal length. Expand the box below to see how zip() and itertools.zip_longest() handle these:

    +
    +

    The following idiom divides the Lego sets into pairs:

    +
    +
    + 
    >>> num_per_group = 2
+>>> list(zip(*[iter(names)] * num_per_group))
+[('Louvre', 'Diagon Alley'), ('Saturn V', 'Millennium Falcon')]
+
    +
    +
    +

    There are five sets, a number that doesn’t divide evenly into pairs. In this case, the default behavior of zip(), where the last element is dropped, might make sense. You could use strict=True here as well, but that would raise an error when your list can’t be split into pairs. A third option, which could be the best in this case, is to use zip_longest() from the itertools standard library.

    +

    As the name suggests, zip_longest() combines sequences until the longest sequence is exhausted. If you use zip_longest() to divide the Lego sets, it becomes more explicit that New York City doesn’t have any pairing:

    +
    +
    + 
    >>> from itertools import zip_longest
+
+>>> list(zip_longest(*[iter(names)] * num_per_group, fillvalue=""))
+[('Louvre', 'Diagon Alley'),
+ ('Saturn V', 'Millennium Falcon'),
+ ('NYC', '')]
+
    +
    +
    +

    Note that 'NYC' shows up in the last tuple together with an empty string. You can control what’s filled in for missing values with the fillvalue parameter.

    +
    +

    While strict is not really adding any new functionality to zip(), it can help you avoid those hard-to-find bugs.

    +
    +
    +

    New Functions in the statistics Module +

    +

    The statistics module was added to the standard library all the way back in 2014 with the release of Python 3.4. The intent of statistics is to make statistical calculations at the level of graphing calculators available in Python.

    +

    Python 3.10 adds a few multivariable functions to statistics:

    +
      +
    • + correlation() to calculate Pearson’s correlation coefficient for two variables +
      • +
    • + covariance() to calculate sample covariance for two variables +
      • +
    • + linear_regression() to calculate the slope and intercept in a linear regression +
      • +
    +

    You can use each function to describe a certain aspect of the relationship between two variables. As an example, say that you have data from a set of blog posts—the number of words in each blog post and the number of views each post has had over some time period:

    +
    +
    + 
    >>> words = [7742, 11539, 16898, 13447, 4608, 6628, 2683, 6156, 2623, 6948]
+>>> views = [8368, 5901, 3978, 3329, 2611, 2096, 1515, 1177, 814, 467]
+
    +
    +
    +

    You now want to investigate whether there’s any (linear) relationship between the number of words and number of views. In Python 3.10, you can calculate the correlation between words and views with the new correlation() function:

    +
    +
    + 
    >>> import statistics
+
+>>> statistics.correlation(words, views)
+0.454180067865917
+
    +
    +
    +

    The correlation between two variables is always a number between -1 and 1. If it’s close to 0, then there’s little correspondence between them, while a correlation close to -1 or 1 indicates that the behaviors of the two variables tend to follow each other. In this example, a correlation of 0.45 indicates that there’s a tendency for posts with more words to have more views, although it’s not a strong connection.

    +

    You can also calculate the covariance between words and views. The covariance is another measure of the joint variability between two variables. You can calculate it with covariance():

    +
    +
    + 
    >>> import statistics
+
+>>> statistics.covariance(words, views)
+5292289.977777777
+
    +
    +
    +

    In contrast to correlation, covariance is an absolute measure. It should be interpreted in the context of the variability within the variables themselves. In fact, you can normalize the covariance by the standard deviation of each variable to recover Pearson’s correlation coefficient:

    +
    +
    + 
    >>> import statistics
+
+>>> cov = statistics.covariance(words, views)
+>>> σ_words, σ_views = statistics.stdev(words), statistics.stdev(views)
+>>> cov / (σ_words * σ_views)
+0.454180067865917
+
    +
    +
    +

    Note that this matches your earlier correlation coefficient exactly.

    +

    A third way of looking at the linear correspondence between the two variables is through simple linear regression. You do the linear regression by calculating two numbers, slope and intercept, so that the (squared) error is minimized in the approximation number of views = slope × number of words + intercept.

    +

    In Python 3.10, you can use linear_regression():

    +
    +
    + 
    >>> import statistics
+
+>>> statistics.linear_regression(words, views)
+LinearRegression(slope=0.2424443064354672, intercept=1103.6954940247645)
+
    +
    +
    +

    Based on this regression, a post with 10,074 words could expect about 0.2424 × 10074 + 1104 = 3546 views. However, as you saw earlier, the correlation between the number of words and the number of views is quite weak. Therefore, you shouldn’t expect this prediction to be very accurate.

    +

    The LinearRegression object is a named tuple. This means that you can unpack the slope and intercept directly:

    +
    +
    + 
    >>> import statistics
+
+>>> slope, intercept = statistics.linear_regression(words, views)
+>>> slope * 10074 + intercept
+3546.0794370556605
+
    +
    +
    +

    Here, you use slope and intercept to predict the number of views on a blog post with 10,074 words.

    +

    You still want to use some of the more advanced packages like pandas and statsmodels if you do a lot of statistical analysis. With the new additions to statistics in Python 3.10, however, you have the chance to do basic analysis more easily without bringing in third-party dependencies.

    +
    +
    +

    Other Pretty Cool Features +

    +

    So far, you’ve seen the biggest and most impactful new features in Python 3.10. In this section, you’ll get a glimpse of a few of the other changes that the new version brings along. If you’re curious about all the changes made for this new version, check out the documentation.

    +
    +

    Default Text Encodings +

    +

    When you open a text file, the default encoding used to interpret the characters is system dependent. In particular, locale.getpreferredencoding() is used. On Mac and Linux, this usually returns "UTF-8", while the result on Windows is more varied.

    +

    You should therefore always specify an encoding when you attempt to open a text file:

    +
    +
    + 
    with open("some_file.txt", mode="r", encoding="utf-8") as file:
+    ...  # Do something with file
+
    +
    +
    +

    If you don’t explicitly specify an encoding, the preferred locale encoding is used, and you could experience that a file that can be read on one computer fails to open on another.

    +

    Python 3.7 introduced UTF-8 mode, which allows you to force your programs to use UTF-8 encoding independent of the locale encoding. You can enable UTF-8 mode by giving the -X utf8 command-line option to the python executable or by setting the PYTHONUTF8 environment variable.

    +

    In Python 3.10, you can activate a warning that will tell you when a text file is opened without a specified encoding. Consider the following script, which doesn’t specify an encoding:

    +
    +
    + 
    # mirror.py
+
+import pathlib
+import sys
+
+def mirror_file(filename):
+    for line in pathlib.Path(filename).open(mode="r"):
+        print(f"{line.rstrip()[::-1]:>72}")
+
+if __name__ == "__main__":
+    for filename in sys.argv[1:]:
+        mirror_file(filename)
+
    +
    +
    +

    The program will echo one or more text files back to the console, but with each line reversed. Run the program on itself with the encoding warning enabled:

    +
    +
    + 
    $ python -X warn_default_encoding mirror.py mirror.py
+/home/rp/mirror.py:7: EncodingWarning: 'encoding' argument not specified
+  for line in pathlib.Path(filename).open(mode="r"):
+                                                             yp.rorrim #
+
+                                                          bilhtap tropmi
+                                                              sys tropmi
+
+                                              :)emanelif(elif_rorrim fed
+                  :)"r"=edom(nepo.)emanelif(htaP.bilhtap ni enil rof
+                             )"}27>:]1-::[)(pirtsr.enil{"f(tnirp
+
+                                              :"__niam__" == __eman__ fi
+                                       :]:1[vgra.sys ni emanelif rof
+                                           )emanelif(elif_rorrim
+
    +
    +
    +

    Note the EncodingWarning printed to the console. The command-line option -X warn_default_encoding activates it. The warning will disappear if you specify an encoding—for example, encoding="utf-8"—when you open the file.

    +

    There are times when you want to use the user-defined local encoding. You can still do so by explicitly using encoding="locale". However, it’s recommended to use UTF-8 whenever possible. You can check out PEP 597 for more information.

    +
    +
    +

    Asynchronous Iteration +

    +

    + Asynchronous programming is a powerful programming paradigm that’s been available in Python since version 3.5. You can recognize an asynchronous program by its use of the async keyword or special methods that start with .__a like .__aiter__() or .__aenter__(). +

    +

    In Python 3.10, two new asynchronous built-in functions are added: aiter() and anext(). In practice, these functions call the .__aiter__() and .__anext__() special methods—analogous to the regular iter() and next()—so no new functionality is added. These are convenience functions that make your code more readable.

    +

    In other words, in the newest version of Python, the following statements—where things is an asynchronous iterable—are equivalent:

    +
    +
    + 
    >>> it = things.__aiter__()
+>>> it = aiter(things)
+
    +
    +
    +

    In either case, it ends up as an asynchronous iterator. Expand the following box to see a complete example using aiter() and anext():

    +
    +

    The following program counts the number of lines in several files. In practice, you use Python’s ability to iterate over files to count the number of lines. The script uses asynchronous iteration in order to handle several files concurrently.

    +

    Note that you need to install the third-party aiofiles package with pip before running this code:

    +
    +
    + 
    # line_count.py
+
+import asyncio
+import sys
+import aiofiles
+
+async def count_lines(filename):
+    """Count the number of lines in the given file"""
+    num_lines = 0
+
+    async with aiofiles.open(filename, mode="r") as file:
+        lines = aiter(file)
+        while True:
+            try:
+                await anext(lines)
+                num_lines += 1
+            except StopAsyncIteration:
+                break
+
+    print(f"{filename}: {num_lines}")
+
+async def count_all_files(filenames):
+    """Asynchronously count lines in all files"""
+    tasks = [asyncio.create_task(count_lines(f)) for f in filenames]
+    await asyncio.gather(*tasks)
+
+if __name__ == "__main__":
+    asyncio.run(count_all_files(filenames=sys.argv[1:]))
+
    +
    +
    +

    + asyncio is used to create and run one asynchronous task per filename. count_lines() opens one file asynchronously and iterates through it using aiter() and anext() in order to count the number of lines. +

    +
    +

    See PEP 525 to learn more about asynchronous iteration.

    +
    +
    +

    Context Manager Syntax +

    +

    + Context managers are great for managing resources in your programs. Until recently, though, their syntax has included an uncommon wart. You haven’t been allowed to use parentheses to break long with statements like this: +

    +
    +
    + 
    with (
+    read_path.open(mode="r", encoding="utf-8") as read_file,
+    write_path.open(mode="w", encoding="utf-8") as write_file,
+):
+    ...
+
    +
    +
    +

    In earlier versions of Python, this causes an invalid syntax error message. Instead, you need to use a backslash (\) if you want to control where you break your lines:

    +
    +
    + 
    with read_path.open(mode="r", encoding="utf-8") as read_file, \
+     write_path.open(mode="w", encoding="utf-8") as write_file:
+    ...
+
    +
    +
    +

    While explicit line continuation with backslashes is possible in Python, PEP 8 discourages it. The Black formatting tool avoids backslashes completely.

    +

    In Python 3.10, you’re now allowed to add parentheses around with statements to your heart’s content. Especially if you’re employing several context managers at once, like in the example above, this can help improve the readability of your code. Python’s documentation shows a few other possibilities with this new syntax.

    +

    One small fun fact: parenthesized with statements actually work in version 3.9 of CPython. Their implementation came almost for free with the introduction of the PEG parser in Python 3.9. The reason that this is called a Python 3.10 feature is that using the PEG parser is voluntary in Python 3.9, while Python 3.9, with the old LL(1) parser, doesn’t support parenthesized with statements.

    +
    +
    +

    Modern and Secure SSL +

    +

    Security can be challenging! A good rule of thumb is to avoid rolling your own security algorithms and instead rely on established packages.

    +

    Python uses OpenSSL for different cryptographic features that are exposed in the hashlib, hmac, and ssl standard library modules. Your system can manage OpenSSL, or a Python installer can include OpenSSL.

    +

    Python 3.9 supports using any of the OpenSSL versions 1.0.2 LTS, 1.1.0, and 1.1.1 LTS. Both OpenSSL 1.0.2 LTS and OpenSSL 1.1.0 are past their lifetime, so Python 3.10 will only support OpenSSL 1.1.1 LTS, as described in the following table:

    +
    + + + + + + + + + + + + + + + + + + + + + + + + + + +
    Open SSL version Python 3.9 Python 3.10 End-of-life
    1.0.2 LTS ✔ ✖
    1.1.0 ✔ ✖
    1.1.1 LTS ✔ ✔
    +
    +

    This end of support for older versions will only affect you if you need to upgrade the system Python on an older operating system. If you use macOS or Windows, or if you install Python from python.org or use (Ana)Conda, you’ll see no change.

    +

    However, Ubuntu 18.04 LTS uses OpenSSL 1.1.0, while Red Hat Enterprise Linux (RHEL) 7 and CentOS 7 both use OpenSSL 1.0.2 LTS. If you need to run Python 3.10 on these systems, you should look at installing it yourself using either the python.org or Conda installer.

    +

    Dropping support for older versions of OpenSSL will make Python more secure. It’ll also help the Python developers in that code will be easier to maintain. Ultimately, this helps you because your Python experience will be more robust. See PEP 644 for more details.

    +
    +
    +

    More Information About Your Python Interpreter +

    +

    The sys module contains a lot of information about your system, the current Python runtime, and the script currently being executed. You can, for example, inquire about the paths where Python looks for modules with sys.path and see all modules that have been imported in the current session with sys.modules.

    +

    In Python 3.10, sys has two new attributes. First, you can now get a list of the names of all modules in the standard library:

    +
    +
    + 
    >>> import sys
+
+>>> len(sys.stdlib_module_names)
+302
+
+>>> sorted(sys.stdlib_module_names)[-5:]
+['zipapp', 'zipfile', 'zipimport', 'zlib', 'zoneinfo']
+
    +
    +
    +

    Here, you can see that there are around 300 modules in the standard library, several of which start with the letter z. Note that only top-level modules and packages are listed. Subpackages like importlib.metadata don’t get a separate entry.

    +

    You will probably not be using sys.stdlib_module_names all that often. Still, the list ties in nicely with similar introspection features like keyword.kwlist and sys.builtin_module_names.

    +

    One possible use case for the new attribute is to identify which of the currently imported modules are third-party dependencies:

    +
    +
    + 
    >>> import pandas as pd
+>>> import sys
+
+>>> {m for m in sys.modules if "." not in m} - sys.stdlib_module_names
+{'__main__', 'numpy', '_cython_0_29_24', 'dateutil', 'pytz',
+ 'six', 'pandas', 'cython_runtime'}
+
    +
    +
    +

    You find the imported top-level modules by looking at names in sys.modules that don’t have a dot in their name. By comparing them to the standard library module names, you find that numpy, dateutil, and pandas are some of the imported third-party modules in this example.

    +

    The other new attribute is sys.orig_argv. This is related to sys.argv, which holds the command-line arguments given to your program when it was started. In contrast, sys.orig_argv lists the command-line arguments passed to the python executable itself. Consider the following example:

    +
    +
    + 
    # argvs.py
+
+import sys
+
+print(f"argv: {sys.argv}")
+print(f"orig_argv: {sys.orig_argv}")
+
    +
    +
    +

    This script echoes back the orig_argv and argv lists. Run it to see how the information is captured:

    +
    +
    + 
    $ python -X utf8 -O argvs.py 3.10 --upgrade
+argv: ['argvs.py', '3.10', '--upgrade']
+orig_argv: ['python', '-X', 'utf8', '-O', 'argvs.py', '3.10', '--upgrade']
+
    +
    +
    +

    Essentially, all arguments—including the name of the Python executable—end up in orig_argv. This is in contrast to argv, which only contains the arguments that aren’t handled by python itself.

    +

    Again, this is not a feature that you’ll use a lot. If your program needs to concern itself with how it’s being run, you’re usually better off relying on information that’s already exposed instead of trying to parse this list. For example, you can choose to use the strict zip() mode only when your script is not running with the optimized flag, -O, like this:

    +
    +
    + 
    list(zip(names, set_numbers, num_pieces, strict=__debug__))
+
    +
    +
    +

    The __debug__ flag is set when the interpreter starts. It’ll be False if you’re running python with -O or -OO specified, and True otherwise. Using __debug__ is usually preferable to "-O" not in sys.orig_argv or some similar construct.

    +

    One of the motivating use cases for sys.orig_argv is that you can use it to spawn a new Python process with the same or modified command-line arguments as your current process.

    +
    +
    +

    Future Annotations +

    +

    + Annotations were introduced in Python 3 to give you a way to attach metadata to variables, function parameters, and return values. They are most commonly used to add type hints to your code. +

    +

    One challenge with annotations is that they must be valid Python code. For one thing, this makes it hard to type hint recursive classes. PEP 563 introduced postponed evaluation of annotations, making it possible to annotate with names that haven’t yet been defined. Since Python 3.7, you can activate postponed evaluation of annotations with a __future__ import:

    +
    +
    + 
    from __future__ import annotations
+
    +
    +
    +

    The intention was that postponed evaluation would become the default at some point in the future. After the 2020 Python Language Summit, it was decided to make this happen in Python 3.10.

    +

    However, after more testing, it became clear that postponed evaluation didn’t work well for projects that use annotations at runtime. Key people in the FastAPI and the Pydantic projects voiced their concerns. At the last minute, it was decided to reschedule these changes for Python 3.11.

    +

    To ease the transition into future behavior, a few changes have been made in Python 3.10 as well. Most importantly, a new inspect.get_annotations() function has been added. You should call this to access annotations at runtime:

    +
    +
    + 
    >>> import inspect
+
+>>> def mean(numbers: list[int | float]) -> float:
+...     return sum(numbers) / len(numbers)
+...
+
+>>> inspect.get_annotations(mean)
+{'numbers': list[int | float], 'return': <class 'float'>}
+
    +
    +
    +

    Check out Annotations Best Practices for details.

    +
    +
    +
    +

    How to Detect Python 3.10 at Runtime +

    +

    Python 3.10 is the first version of Python with a two-digit minor version number. While this is mostly an interesting fun fact and an indication that Python 3 has been around for quite some time, it does also have some practical consequences.

    +

    When your code needs to do something specific based on the version of Python at runtime, you’ve gotten away with doing a lexicographical comparison of version strings until now. While it’s never been good practice, it’s been possible to do the following:

    +
    +
    + 
    # bad_version_check.py
+
+import sys
+
+# Don't do the following
+if sys.version < "3.6":
+    raise SystemExit("Only Python 3.6 and above is supported")
+
    +
    +
    +

    In Python 3.10, this code will raise SystemExit and stop your program. This happens because, as strings, "3.10" is less than "3.6".

    +

    The correct way to compare version numbers is to use tuples of numbers:

    +
    +
    + 
    # good_version_check.py
+
+import sys
+
+if sys.version_info < (3, 6):
+    raise SystemExit("Only Python 3.6 and above is supported")
+
    +
    +
    +

    + sys.version_info is a tuple object you can use for comparisons. +

    +

    If you’re doing these kinds of comparisons in your code, you should check your code with flake8-2020 to make sure you’re handling versions correctly:

    +
    +
    + 
    $ python -m pip install flake8-2020
+
+$ flake8 bad_version_check.py good_version_check.py
+bad_version_check.py:3:4: YTT103 `sys.version` compared to string
+                          (python3.10), use `sys.version_info`
+
    +
    +
    +

    With the flake8-2020 extension activated, you’ll get a recommendation about replacing sys.version with sys.version_info.

    +
    +
    +

    So, Should You Upgrade to Python 3.10? +

    +

    You’ve now seen the coolest features of the newest and latest version of Python. The question now is whether you should upgrade to Python 3.10, and if yes, when you should do so. There are two different aspects to consider when thinking about upgrading to Python 3.10:

    +
      +
    1. Should you upgrade your environment so that you run your code with the Python 3.10 interpreter?
      2. +
    2. Should you write your code using the new Python 3.10 features?
      3. +
    +

    Clearly, if you want to test out structural pattern matching or any of the other cool new features you’ve read about here, you need Python 3.10. It’s possible to install the latest version side by side with your current Python version. A straightforward way to do this is to use an environment manager like pyenv or Conda. You can also use Docker to run Python 3.10 without installing it locally.

    +

    Python 3.10 has been through about five months of beta testing, so there shouldn’t be any big issues with starting to use it for your own development. You may find that some of your dependencies don’t immediately have wheels for Python 3.10 available, which makes them more cumbersome to install. But in general, using the newest Python for local development is fairly safe.

    +

    As always, you should be careful before upgrading your production environment. Be vigilant about testing that your code runs well on the new version. In particular, you want to be on the lookout for features that are deprecated or removed.

    +

    Whether you can start using the new features in your code or not depends on your user base and the environment where your code is running. If you can guarantee that Python 3.10 is available, then there’s no danger in using the new union type syntax or any other new feature.

    +

    If you’re distributing an app or a library that’s used by others instead, you may want to be a bit more conservative. Currently, Python 3.6 is the oldest officially supported Python version. It reaches end-of-life in December 2021, after which Python 3.7 will be the minimum supported version.

    +

    The documentation includes a useful guide about porting your code to Python 3.10. Check it out for more details!

    +
    +
    +

    Conclusion +

    +

    The release of a new Python version is always worth celebrating. Even if you can’t start using the new features right away, they’ll become broadly available and part of your daily life within a few years.

    +

    + In this tutorial, you’ve seen new features like: +

    +
      +
    • Friendlier error messages +
      • +
    • Powerful structural pattern matching +
      • +
    • + Type hint improvements +
      • +
    • Safer combination of sequences +
      • +
    • New statistics functions +
      • +
    +

    For more Python 3.10 tips and a discussion with members of the Real Python team, check out Real Python Podcast Episode #81.

    +

    Have fun trying out the new features! Share your experiences in the comments below.

    +
    +

    + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    +
    +
    +

    Get a short & sweet Python Trick delivered to your inbox every couple of days. No spam ever. Unsubscribe any time. Curated by the Real Python team.

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    + Each tutorial at Real Python is created by a team of developers so that it meets our high quality standards. The team members who worked on this tutorial are: +

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    \ No newline at end of file diff --git a/packages/readabilityjs/test/test-pages/realpython/source.html b/packages/readabilityjs/test/test-pages/realpython/source.html new file mode 100644 index 000000000..b5ffc54f0 --- /dev/null +++ b/packages/readabilityjs/test/test-pages/realpython/source.html @@ -0,0 +1,4150 @@ + + + + + + + Python 3.10: Cool New Features for You to Try – Real Python + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    +
    + +
    +
    + Python 3.10: Cool New Features for You to Try +
    +

    + Python 3.10: Cool New Features for You to Try +

    +
    + by Geir Arne Hjelle + 2 Comments + intermediate python +
    +
    + +
    +
    + + Share + Share + Email +
    +
    +
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    +
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    +
    + Remove ads +
    +
    +

    + + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    +
    +

    + Python 3.10 is out! Volunteers have been working on the new version since May 2020 to bring you a better, faster, and more secure Python. As of October 4, 2021, the first official version is available. +

    +

    + Each new version of Python brings a host of changes. You can read about all of them in the documentation. Here, you’ll get to learn about the coolest new features. +

    +

    + In this tutorial, you’ll learn about: +

    +
      +
    • Debugging with more helpful and precise error messages +
      • +
    • Using structural pattern matching to work with data structures +
      • +
    • Adding more readable and more specific type hints +
      • +
    • Checking the length of sequences when using zip() +
      • +
    • Calculating multivariable statistics +
      • +
    +

    + To try out the new features yourself, you need to run Python 3.10. You can get it from the Python homepage. Alternatively, you can use Docker with the latest Python image. +

    + + +
    +

    + Better Error Messages +

    +

    + Python is often lauded for being a user-friendly programming language. While this is true, there are certain parts of Python that could be friendlier. Python 3.10 comes with a host of more precise and constructive error messages. In this section, you’ll see some of the newest improvements. The full list is available in the documentation. +

    +

    + Think back to writing your first Hello World program in Python: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # hello.py
+
+print("Hello, World!)
+
    +
    + +
    +
    +

    + Maybe you created a file, added the famous call to print(), and saved it as hello.py. You then ran the program, eager to call yourself a proper Pythonista. However, something went wrong: +

    +
    +
    + Shell +
    + + +
    +
    +
    +
    + 
    $ python hello.py
+  File "/home/rp/hello.py", line 3
+    print("Hello, World!)
+                        ^
+SyntaxError: EOL while scanning string literal
+
    +
    + +
    +
    +

    + There was a SyntaxError in the code. EOL, what does that even mean? You went back to your code, and after a bit of staring and searching, you realized that there was a missing quotation mark at the end of your string. +

    +

    + One of the more impactful improvements in Python 3.10 is better and more precise error messages for many common issues. If you run your buggy Hello World in Python 3.10, you’ll get a bit more help than in earlier versions of Python: +

    +
    +
    + Shell +
    + + +
    +
    +
    +
    + 
    $ python hello.py
+  File "/home/rp/hello.py", line 3
+    print("Hello, World!)
+          ^
+SyntaxError: unterminated string literal (detected at line 3)
+
    +
    + +
    +
    +

    + The error message is still a bit technical, but gone is the mysterious EOL. Instead, the message tells you that you need to terminate your string! There are similar improvements to many different error messages, as you’ll see below. +

    +

    + A SyntaxError is an error raised when your code is parsed, before it even starts to execute. Syntax errors can be tricky to debug because the interpreter provides imprecise or sometimes even misleading error messages. The following code is missing a curly brace to terminate the dictionary: +

    +
    +
    + Python +
    +
    +
    +
    + 
     1# unterminated_dict.py
+ 2
+ 3months = {
+ 4    10: "October",
+ 5    11: "November",
+ 6    12: "December"
+ 7
+ 8print(f"{months[10]} is the tenth month")
+
    +
    + +
    +
    +

    + The missing closing curly brace that should have been on line 7 is an error. If you run this code with Python 3.9 or earlier, you’ll see the following error message: +

    +
    +
    + Python Traceback +
    +
    +
    +
    + 
      File "/home/rp/unterminated_dict.py", line 8
+    print(f"{months[10]} is the tenth month")
+    ^
+SyntaxError: invalid syntax
+
    +
    + +
    +
    +

    + The error message highlights line 8, but there are no syntactical problems in line 8! If you’ve experienced your share of syntax errors in Python, you might already know that the trick is to look at the lines before the one Python complains about. In this case, you’re looking for the missing closing brace on line 7. +

    +

    + In Python 3.10, the same code shows a much more helpful and precise error message: +

    +
    +
    + Python Traceback +
    +
    +
    +
    + 
      File "/home/rp/unterminated_dict.py", line 3
+    months = {
+             ^
+SyntaxError: '{' was never closed
+
    +
    + +
    +
    +

    + This points you straight to the offending dictionary and allows you to fix the issue in no time. +

    +

    + There are a few other ways to mess up dictionary syntax. A typical one is forgetting a comma after one of the items: +

    +
    +
    + Python +
    +
    +
    +
    + 
     1# missing_comma.py
+ 2
+ 3months = {
+ 4    10: "October"
+ 5    11: "November",
+ 6    12: "December",
+ 7}
+
    +
    + +
    +
    +

    + In this code, a comma is missing at the end of line 4. Python 3.10 gives you a clear suggestion on how to fix your code: +

    +
    +
    + Python Traceback +
    +
    +
    +
    + 
      File "/home/real_python/missing_comma.py", line 4
+    10: "October"
+        ^^^^^^^^^
+SyntaxError: invalid syntax. Perhaps you forgot a comma?
+
    +
    + +
    +
    +

    + You can add the missing comma and have your code back up and running in no time. +

    +

    + Another common mistake is using the assignment operator (=) instead of the equality comparison operator (==) when you’re comparing values. Previously, this would just cause another invalid syntax message. In the newest version of Python, you get some more advice: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> if month = "October":
+  File "<stdin>", line 1
+    if month = "October":
+       ^^^^^^^^^^^^^^^^^
+SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?
+
    +
    + +
    +
    +

    + The parser suggests that you maybe meant to use a comparison operator or an assignment expression operator instead. +

    +

    + Take note of another nifty improvement in Python 3.10 error messages. The last two examples show how carets (^^^) highlight the whole offending expression. Previously, a single caret symbol (^) indicated just an approximate location. +

    +

    + The final error message improvement that you’ll play with for now is that attribute and name errors can now offer suggestions if you misspell an attribute or a name: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import math
+>>> math.py
+AttributeError: module 'math' has no attribute 'py'. Did you mean: 'pi'?
+
+>>> pint
+NameError: name 'pint' is not defined. Did you mean: 'print'?
+
+>>> release = "3.10"
+>>> relaese
+NameError: name 'relaese' is not defined. Did you mean: 'release'?
+
    +
    + +
    +
    +

    + Note that the suggestions work for both built-in names and names that you define yourself, although they may not be available in all environments. If you like these kinds of suggestions, check out BetterErrorMessages, which offers similar suggestions in even more contexts. +

    +

    + The improvements you’ve seen in this section are just some of the many error messages that have gotten a face-lift. The new Python will be even more user-friendly than before, and hopefully, the new error messages will save you both time and frustration going forward. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Structural Pattern Matching +

    +

    + The biggest new feature in Python 3.10, probably both in terms of controversy and potential impact, is structural pattern matching. Its introduction has sometimes been referred to as switch ... case coming to Python, but you’ll see that structural pattern matching is much more powerful than that. +

    +

    + You’ll see three different examples that together highlight why this feature is called structural pattern matching and show you how you can use this new feature: +

    +
      +
    1. Detecting and deconstructing different structures in your data +
      2. +
    2. Using different kinds of patterns +
      3. +
    3. + Matching literal patterns +
      4. +
    +

    + Structural pattern matching is a comprehensive addition to the Python language. To give you a taste of how you can take advantage of it in your own projects, the next three subsections will dive into some of the details. You’ll also see some links that can help you explore in even more depth if you want. +

    +
    +

    + Deconstructing Data Structures +

    +

    + At its core, structural pattern matching is about defining patterns to which your data structures can be matched. In this section, you’ll study a practical example where you’ll work with data that are structured differently, even though the meaning is the same. You’ll define several patterns, and depending on which pattern matches your data, you’ll process your data appropriately. +

    +

    + This section will be a bit light on explanations of the possible patterns. Instead, it will try to give you an impression of the possibilities. The next section will step back and explain the patterns in more detail. +

    +

    + Time to match your first pattern! The following example uses a match ... case block to find the first name of a user by extracting it from a user data structure: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> user = {
+...     "name": {"first": "Pablo", "last": "Galindo Salgado"},
+...     "title": "Python 3.10 release manager",
+... }
+
+>>> match user:
+...     case {"name": {"first": first_name}}:
+...         pass
+...
+
+>>> first_name
+'Pablo'
+
    +
    + +
    +
    +

    + You can see structural pattern matching at work in the highlighted lines. user is a small dictionary with user information. The case line specifies a pattern that user is matched against. In this case, you’re looking for a dictionary with a "name" key whose value is a new dictionary. This nested dictionary has a key called "first". The corresponding value is bound to the variable first_name. +

    +

    + For a practical example, say that you’re processing user data where the underlying data model changes over time. Therefore, you need to be able to process different versions of the same data. +

    +

    + In the next example, you’ll use data from randomuser.me. This is a great API for generating random user data that you can use during testing and development. The API is also an example of an API that has changed over time. You can still access the old versions of the API. +

    +

    + You may expand the collapsed section below to see how you can use requests to obtain different versions of the user data using the API: +

    +
    +
    +

    + +

    +
    +
    +
    +

    + You can get a random user from the API using requests as follows: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # random_user.py
+
+import requests
+
+def get_user(version="1.3"):
+    """Get random users"""
+    url = f"https://randomuser.me/api/{version}/?results=1"
+    response = requests.get(url)
+    if response:
+        return response.json()["results"][0]
+
    +
    + +
    +
    +

    + get_user() gets one random user in JSON format. Note the version parameter. The structure of the returned data has changed quite a bit between earlier versions like "1.1" and the current version "1.3", but in each case, the actual user data are contained in a list inside the "results" array. The function returns the first—and only—user in this list. +

    +

    + At the time of writing, the latest version of the API is 1.3 and the data has the following structure: +

    +
    +
    + JSON +
    +
    +
    +
    + 
    {
+    "gender": "female",
+    "name": {
+        "title": "Miss",
+        "first": "Ilona",
+        "last": "Jokela"
+    },
+    "location": {
+        "street": {
+            "number": 4473,
+            "name": "Mannerheimintie"
+        },
+        "city": "Harjavalta",
+        "state": "Ostrobothnia",
+        "country": "Finland",
+        "postcode": 44879,
+        "coordinates": {
+            "latitude": "-6.0321",
+            "longitude": "123.2213"
+        },
+        "timezone": {
+            "offset": "+5:30",
+            "description": "Bombay, Calcutta, Madras, New Delhi"
+        }
+    },
+    "email": "ilona.jokela@example.com",
+    "login": {
+        "uuid": "632b7617-6312-4edf-9c24-d6334a6af52d",
+        "username": "brownsnake482",
+        "password": "biatch",
+        "salt": "ofk518ZW",
+        "md5": "6d589615ca44f6e583c85d45bf431c54",
+        "sha1": "cd87c931d579bdff77af96c09e0eea82d1edfc19",
+        "sha256": "6038ede83d4ce74116faa67fb3b1b2e6f6898e5749b57b5a0312bd46a539214a"
+    },
+    "dob": {
+        "date": "1957-05-20T08:36:09.083Z",
+        "age": 64
+    },
+    "registered": {
+        "date": "2006-07-30T18:39:20.050Z",
+        "age": 15
+    },
+    "phone": "07-369-318",
+    "cell": "048-284-01-59",
+    "id": {
+        "name": "HETU",
+        "value": "NaNNA204undefined"
+    },
+    "picture": {
+        "large": "https://randomuser.me/api/portraits/women/28.jpg",
+        "medium": "https://randomuser.me/api/portraits/med/women/28.jpg",
+        "thumbnail": "https://randomuser.me/api/portraits/thumb/women/28.jpg"
+    },
+    "nat": "FI"
+}
+
    +
    + +
    +
    +

    + One of the members that changed between different versions is "dob", the date of birth. Note that in version 1.3, this is a JSON object with two members, "date" and "age". +

    + +

    + Compare the result above with a version 1.1 random user: +

    +
    +
    + JSON +
    +
    +
    +
    + 
    {
+    "gender": "female",
+    "name": {
+        "title": "miss",
+        "first": "ilona",
+        "last": "jokela"
+    },
+    "location": {
+        "street": "7336 myllypuronkatu",
+        "city": "kurikka",
+        "state": "central ostrobothnia",
+        "postcode": 53740
+    },
+    "email": "ilona.jokela@example.com",
+    "login": {
+        "username": "blackelephant837",
+        "password": "sand",
+        "salt": "yofk518Z",
+        "md5": "b26367ea967600d679ee3e0b9bda012f",
+        "sha1": "87d2910595acba5b8e8aa8b00a841bab08580e2f",
+        "sha256": "73bd0d205d0dc83ae184ae222ff2e9de5ea4039119a962c4f97fabd5bbfa7aca"
+    },
+    "dob": "1966-04-17 11:57:01",
+    "registered": "2005-08-10 10:15:01",
+    "phone": "04-636-931",
+    "cell": "048-828-40-15",
+    "id": {
+        "name": "HETU",
+        "value": "366-9204"
+    },
+    "picture": {
+        "large": "https://randomuser.me/api/portraits/women/24.jpg",
+        "medium": "https://randomuser.me/api/portraits/med/women/24.jpg",
+        "thumbnail": "https://randomuser.me/api/portraits/thumb/women/24.jpg"
+    },
+    "nat": "FI"
+}
+
    +
    + +
    +
    +

    + Observe that in this older format, the value of the "dob" member is a plain string. +

    +
    +
    +
    +

    + In this example, you’ll work with the information about the date of birth (dob) for each user. The structure of these data has changed between different versions of the Random User API: +

    +
    +
    + JSON +
    +
    +
    +
    + 
    # Version 1.1
+"dob": "1966-04-17 11:57:01"
+
+# Version 1.3
+"dob": {"date": "1957-05-20T08:36:09.083Z", "age": 64}
+
    +
    + +
    +
    +

    + Note that in version 1.1, the date of birth is represented as a simple string, while in version 1.3, it’s a JSON object with two members: "date" and "age". Say that you want to find the age of a user. Depending on the structure of your data, you’d either need to calculate the age based on the date of birth or look up the age if it’s already available. +

    + +

    + Traditionally, you would detect the structure of the data with an if test, maybe based on the type of the "dob" field. You can approach this differently in Python 3.10. Now, you can use structural pattern matching instead: +

    +
    +
    + Python +
    +
    +
    +
    + 
     1# random_user.py (continued)
+ 2
+ 3from datetime import datetime
+ 4
+ 5def get_age(user):
+ 6    """Get the age of a user"""
+ 7    match user:
+ 8        case {"dob": {"age": int(age)}}:
+ 9            return age
+10        case {"dob": dob}:
+11            now = datetime.now()
+12            dob_date = datetime.strptime(dob, "%Y-%m-%d %H:%M:%S")
+13            return now.year - dob_date.year
+
    +
    + +
    +
    +

    + The match ... case construct is new in Python 3.10 and is how you perform structural pattern matching. You start with a match statement that specifies what you want to match. In this example, that’s the user data structure. +

    +

    + One or several case statements follow match. Each case describes one pattern, and the indented block beneath it says what should happen if there’s a match. In this example: +

    +
      +
    • +

      + Line 8 matches a dictionary with a "dob" key whose value is another dictionary with an integer (int) item named "age". The name age captures its value. +

      +
      • +
    • +

      + Line 10 matches any dictionary with a "dob" key. The name dob captures its value. +

      +
      • +
    +

    + One important feature of pattern matching is that at most one pattern will be matched. Since the pattern on line 10 matches any dictionary with "dob", it’s important that the more specific pattern on line 8 comes first. +

    + +

    + Before looking closer at the details of the patterns and how they work, try calling get_age() with different data structures to see the result: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import random_user
+
+>>> users11 = random_user.get_user(version="1.1")
+>>> random_user.get_age(users11)
+55
+
+>>> users13 = random_user.get_user(version="1.3")
+>>> random_user.get_age(users13)
+64
+
    +
    + +
    +
    +

    + Your code can calculate the age correctly for both versions of the user data, which have different dates of birth. +

    +

    + Look closer at those patterns. The first pattern, {"dob": {"age": int(age)}}, matches version 1.3 of the user data: +

    +
    +
    + Python +
    +
    +
    +
    + 
    {
+    ...
+    "dob": {"date": "1957-05-20T08:36:09.083Z", "age": 64},
+    ...
+}
+
    +
    + +
    +
    +

    + The first pattern is a nested pattern. The outer curly braces say that a dictionary with the key "dob" is required. The corresponding value should be a dictionary. This nested dictionary must match the subpattern {"age": int(age)}. In other words, it needs to have an "age" key with an integer value. That value is bound to the name age. +

    +

    + The second pattern, {"dob": dob}, matches the older version 1.1 of the user data: +

    +
    +
    + Python +
    +
    +
    +
    + 
    {
+    ...
+    "dob": "1966-04-17 11:57:01",
+    ...
+}
+
    +
    + +
    +
    +

    + This second pattern is a simpler pattern than the first one. Again, the curly braces indicate that it will match a dictionary. However, any dictionary with a "dob" key is matched because there are no other restrictions specified. The value of that key is bound to the name dob. +

    +

    + The main takeaway is that you can describe the structure of your data using mostly familiar notation. One striking change, though, is that you can use names like dob and age, which aren’t yet defined. Instead, values from your data are bound to these names when a pattern matches. +

    +

    + You’ve explored some of the power of structural pattern matching in this example. In the next section, you’ll dive a bit more into the details. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Using Different Kinds of Patterns +

    +

    + You’ve seen an example of how you can use patterns to effectively unravel complicated data structures. Now, you’ll take a step back and look at the building blocks that make up this new feature. Many things come together to make it work. In fact, there are three Python Enhancement Proposals (PEPs) that describe structural pattern matching: +

    +
      +
    1. + PEP 634: Specification +
      2. +
    2. + PEP 635: Motivation and Rationale +
      3. +
    3. + PEP 636: Tutorial +
      4. +
    +

    + These documents give you a lot of background and detail if you’re interested in a deeper dive than what follows. +

    +

    + Patterns are at the center of structural pattern matching. In this section, you’ll learn about some of the different kinds of patterns that exist: +

    +
      +
    • + Mapping patterns match mapping structures like dictionaries. +
      • +
    • + Sequence patterns match sequence structures like tuples and lists. +
      • +
    • + Capture patterns bind values to names. +
      • +
    • + AS patterns bind the value of subpatterns to names. +
      • +
    • + OR patterns match one of several different subpatterns. +
      • +
    • + Wildcard patterns match anything. +
      • +
    • + Class patterns match class structures. +
      • +
    • + Value patterns match values stored in attributes. +
      • +
    • + Literal patterns match literal values. +
      • +
    +

    + You already used several of them in the example in the previous section. In particular, you used mapping patterns to unravel data stored in dictionaries. In this section, you’ll learn more about how some of these work. All the details are available in the PEPs mentioned above. +

    +

    + A capture pattern is used to capture a match to a pattern and bind it to a name. Consider the following recursive function that sums a list of numbers: +

    +
    +
    + Python +
    +
    +
    +
    + 
     1def sum_list(numbers):
+ 2    match numbers:
+ 3        case []:
+ 4            return 0
+ 5        case [first, *rest]:
+ 6            return first + sum_list(rest)
+
    +
    + +
    +
    +

    + The first case on line 3 matches the empty list and returns 0 as its sum. The second case on line 5 uses a sequence pattern with two capture patterns to match lists with one or more elements. The first element in the list is captured and bound to the name first. The second capture pattern, *rest, uses unpacking syntax to match any number of elements. rest will bind to a list containing all elements of numbers except the first one. +

    +

    + sum_list() calculates the sum of a list of numbers by recursively adding the first number in the list and the sum of the rest of the numbers. You can use it as follows: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> sum_list([4, 5, 9, 4])
+22
+
    +
    + +
    +
    +

    + The sum of 4 + 5 + 9 + 4 is correctly calculated to be 22. As an exercise for yourself, you can try to trace the recursive calls to sum_list() to make sure you understand how the code sums the whole list. +

    + +

    + sum_list() handles summing up a list of numbers. Observe what happens if you try to sum anything that isn’t a list: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> print(sum_list("4594"))
+None
+
+>>> print(sum_list(4594))
+None
+
    +
    + +
    +
    +

    + Passing a string or a number to sum_list() returns None. This occurs because none of the patterns match, and the execution continues after the match block. That happens to be the end of the function, so sum_list() implicitly returns None. +

    +

    + Often, though, you want to be alerted about failed matches. You can add a catchall pattern as the final case that handles this by raising an error, for example. You can use the underscore (_) as a wildcard pattern that matches anything without binding it to a name. You can add some error handling to sum_list() as follows: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [first, *rest]:
+            return first + sum_list(rest)
+        case _:
+            wrong_type = numbers.__class__.__name__
+            raise ValueError(f"Can only sum lists, not {wrong_type!r}")
+
    +
    + +
    +
    +

    + The final case will match anything that doesn’t match the first two patterns. This will raise a descriptive error, for instance, if you try to calculate sum_list(4594). This is useful when you need to alert your users that some input was not matched as expected. +

    +

    + Your patterns are still not foolproof, though. Consider what happens if you try to sum a list of strings: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> sum_list(["45", "94"])
+TypeError: can only concatenate str (not "int") to str
+
    +
    + +
    +
    +

    + The base case returns 0, so therefore the summing only works for types that you can add with numbers. Python doesn’t know how to add numbers and text strings together. You can restrict your pattern to only match integers using a class pattern: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [int(first), *rest]:
+            return first + sum_list(rest)
+        case _:
+            raise ValueError(f"Can only sum lists of numbers")
+
    +
    + +
    +
    +

    + Adding int() around first makes sure that the pattern only matches if the value is an integer. This might be too restrictive, though. Your function should be able to sum both integers and floating-point numbers, so how can you allow this in your pattern? +

    +

    + To check whether at least one out of several subpatterns match, you can use an OR pattern. OR patterns consist of two or more subpatterns, and the pattern matches if at least one of the subpatterns does. You can use this to match when the first element is either of type int or type float: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def sum_list(numbers):
+    match numbers:
+        case []:
+            return 0
+        case [int(first) | float(first), *rest]:
+            return first + sum_list(rest)
+        case _:
+            raise ValueError(f"Can only sum lists of numbers")
+
    +
    + +
    +
    +

    + You use the pipe symbol (|) to separate the subpatterns in an OR pattern. Your function now allows summing a list of floating-point numbers: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> sum_list([45.94, 46.17, 46.72])
+138.82999999999998
+
    +
    + +
    +
    +

    + There’s a lot of power and flexibility within structural pattern matching, even more than what you’ve seen so far. Some things that aren’t covered in this overview are: +

    + +

    + If you’re interested, have a look in the documentation to learn more about these features as well. In the next section, you’ll learn about literal patterns and value patterns. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Matching Literal Patterns +

    +

    + A literal pattern is a pattern that matches a literal object like an explicit string or number. In a sense, this is the most basic kind of pattern and allows you to emulate switch ... case statements seen in other languages. The following example matches a specific name: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def greet(name):
+    match name:
+        case "Guido":
+            print("Hi, Guido!")
+        case _:
+            print("Howdy, stranger!")
+
    +
    + +
    +
    +

    + The first case matches the literal string "Guido". In this case, you use _ as a wildcard to print a generic greeting whenever name is not "Guido". Such literal patterns can sometimes take the place of if ... elif ... else constructs and can play the same role that switch ... case does in some other languages. +

    +

    + One limitation with structural pattern matching is that you can’t directly match values stored in variables. Say that you’ve defined bdfl = "Guido". A pattern like case bdfl: will not match "Guido". Instead, this will be interpreted as a capture pattern that matches anything and binds that value to bdfl, effectively overwriting the old value. +

    +

    + You can, however, use a value pattern to match stored values. A value pattern looks a bit like a capture pattern but uses a previously defined dotted name that holds the value that will be matched against. +

    + +

    + You can, for example, use an enumeration to create such dotted names: +

    +
    +
    + Python +
    +
    +
    +
    + 
    import enum
+
+class Pythonista(str, enum.Enum):
+    BDFL = "Guido"
+    FLUFL = "Barry"
+
+def greet(name):
+    match name:
+        case Pythonista.BDFL:
+            print("Hi, Guido!")
+        case _:
+            print("Howdy, stranger!")
+
    +
    + +
    +
    +

    + The first case now uses a value pattern to match Pythonista.BDFL, which is "Guido". Note that you can use any dotted name in a value pattern. You could, for example, have used a regular class or a module instead of the enumeration. +

    +

    + To see a bigger example of how to use literal patterns, consider the game of FizzBuzz. This is a counting game where you should replace some numbers with words according to the following rules: +

    +
      +
    • You replace numbers divisible by 3 with fizz. +
      • +
    • You replace numbers divisible by 5 with buzz. +
      • +
    • You replace numbers divisible by both 3 and 5 with fizzbuzz. +
      • +
    +

    + FizzBuzz is sometimes used to introduce conditionals in programming education and as a screening problem in interviews. Even though a solution is quite straightforward, Joel Grus has written a full book about different ways to program the game. +

    +

    + A typical solution in Python will use if ... elif ... else as follows: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def fizzbuzz(number):
+    mod_3 = number % 3
+    mod_5 = number % 5
+
+    if mod_3 == 0 and mod_5 == 0:
+        return "fizzbuzz"
+    elif mod_3 == 0:
+        return "fizz"
+    elif mod_5 == 0:
+        return "buzz"
+    else:
+        return str(number)
+
    +
    + +
    +
    +

    + The % operator calculates the modulus, which you can use to test divisibility. Namely, if a modulus b is 0 for two numbers a and b, then a is divisible by b. +

    +

    + In fizzbuzz(), you calculate number % 3 and number % 5, which you then use to test for divisibility with 3 and 5. Note that you must do the test for divisibility with both 3 and 5 first. If not, numbers that are divisible by both 3 and 5 will be covered by either the "fizz" or the "buzz" cases instead. +

    +

    + You can check that your implementation gives the expected result: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> fizzbuzz(3)
+fizz
+
+>>> fizzbuzz(14)
+14
+
+>>> fizzbuzz(15)
+fizzbuzz
+
+>>> fizzbuzz(92)
+92
+
+>>> fizzbuzz(65)
+buzz
+
    +
    + +
    +
    +

    + You can confirm for yourself that 3 is divisible by 3, 65 is divisible by 5, and 15 is divisible by both 3 and 5, while 14 and 92 aren’t divisible by either 3 or 5. +

    +

    + An if ... elif ... else structure where you’re comparing one or a few variables several times over is quite straightforward to rewrite using pattern matching instead. For example, you can do the following: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def fizzbuzz(number):
+    mod_3 = number % 3
+    mod_5 = number % 5
+
+    match (mod_3, mod_5):
+        case (0, 0):
+            return "fizzbuzz"
+        case (0, _):
+            return "fizz"
+        case (_, 0):
+            return "buzz"
+        case _:
+            return str(number)
+
    +
    + +
    +
    +

    + You match on both mod_3 and mod_5. Each case pattern then matches either the literal number 0 or the wildcard _ on the corresponding values. +

    +

    + Compare and contrast this version with the previous one. Note how the pattern (0, 0) corresponds to the test mod_3 == 0 and mod_5 == 0, while (0, _) corresponds to mod_3 == 0. +

    +

    + As you saw earlier, you can use an OR pattern to match on several different patterns. For example, since mod_3 can only take the values 0, 1, and 2, you can replace case (_, 0) with case (1, 0) | (2, 0). Remember that (0, 0) has already been covered. +

    + +

    + The Python core developers have consciously chosen not to include switch ... case statements in the language earlier. However, there are some third-party packages that do, like switchlang, which adds a switch command that also works on earlier versions of Python. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +
    +

    + Type Unions, Aliases, and Guards +

    +

    + Reliably, each new Python release brings some improvements to the static typing system. Python 3.10 is no exception. In fact, four different PEPs about typing accompany this new release: +

    +
      +
    1. + PEP 604: Allow writing union types as X | Y +
      2. +
    2. + PEP 613: Explicit Type Aliases +
      3. +
    3. + PEP 647: User-Defined Type Guards +
      4. +
    4. + PEP 612: Parameter Specification Variables +
      5. +
    +

    + PEP 604 will probably be the most widely used of these changes going forward, but you’ll get a brief overview of each of the features in this section. +

    +

    + You can use union types to declare that a variable can have one of several different types. For example, you’ve been able to type hint a function calculating the mean of a list of numbers, floats, or integers as follows: +

    +
    +
    + Python +
    +
    +
    +
    + 
    from typing import List, Union
+
+def mean(numbers: List[Union[float, int]]) -> float:
+    return sum(numbers) / len(numbers)
+
    +
    + +
    +
    +

    + The annotation List[Union[float, int]] means that numbers should be a list where each element is either a floating-point number or an integer. This works well, but the notation is a bit verbose. Also, you need to import both List and Union from typing. +

    + +

    + In Python 3.10, you can replace Union[float, int] with the more succinct float | int. Combine this with the ability to use list instead of typing.List in type hints, which Python 3.9 introduced. You can then simplify your code while keeping all the type information: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def mean(numbers: list[float | int]) -> float:
+    return sum(numbers) / len(numbers)
+
    +
    + +
    +
    +

    + The annotation of numbers is easier to read now, and as an added bonus, you didn’t need to import anything from typing. +

    +

    + A special case of union types is when a variable can have either a specific type or be None. You can annotate such optional types either as Union[None, T] or, equivalently, Optional[T] for some type T. There is no new, special syntax for optional types, but you can use the new union syntax to avoid importing typing.Optional: +

    +
    +
    + Python +
    +
    +
    +
    + 
    address: str | None
+
    +
    + +
    +
    +

    + In this example, address is allowed to be either None or a string. +

    +

    + You can also use the new union syntax at runtime in isinstance() or issubclass() tests: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> isinstance("mypy", str | int)
+True
+
+>>> issubclass(str, int | float | bytes)
+False
+
    +
    + +
    +
    +

    + Traditionally, you’ve used tuples to test for several types at once—for example, (str, int) instead of str | int. This old syntax will still work. +

    +

    + Type aliases allow you to quickly define new aliases that can stand in for more complicated type declarations. For example, say that you’re representing a playing card using a tuple of suit and rank strings and a deck of cards by a list of such playing card tuples. A deck of cards is then type hinted as list[tuple[str, str]]. +

    +

    + To simplify type annotation, you define type aliases as follows: +

    +
    +
    + Python +
    +
    +
    +
    + 
    Card = tuple[str, str]
+Deck = list[Card]
+
    +
    + +
    +
    +

    + This usually works okay. However, it’s often not possible for the type checker to know whether such a statement is a type alias or just the definition of a regular global variable. To help the type checker—or really, help the type checker help you—you can now explicitly annotate type aliases: +

    +
    +
    + Python +
    +
    +
    +
    + 
    from typing import TypeAlias
+
+Card: TypeAlias = tuple[str, str]
+Deck: TypeAlias = list[Card]
+
    +
    + +
    +
    +

    + Adding the TypeAlias annotation clarifies the intention, both to a type checker and to anyone reading your code. +

    +

    + Type guards are used to narrow down union types. The following function takes in either a string or None but always returns a tuple of strings representing a playing card: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def get_ace(suit: str | None) -> tuple[str, str]:
+    if suit is None:
+        suit = "♠"
+    return (suit, "A")
+
    +
    + +
    +
    +

    + The highlighted line works as a type guard, and static type checkers are able to realize that suit is necessarily a string when it’s returned. +

    +

    + Currently, the type checkers can only use a few different constructs to narrow down union types in this way. With the new typing.TypeGuard, you can annotate custom functions that can be used to narrow down union types: +

    +
    +
    + Python +
    +
    +
    +
    + 
    from typing import Any, TypeAlias, TypeGuard
+
+Card: TypeAlias = tuple[str, str]
+Deck: TypeAlias = list[Card]
+
+def is_deck_of_cards(obj: Any) -> TypeGuard[Deck]:
+    # Return True if obj is a deck of cards, otherwise False
+
    +
    + +
    +
    +

    + is_deck_of_cards() should return True or False depending on whether obj represents a Deck object or not. You can then use your guard function, and the type checker will be able to narrow down the types correctly: +

    +
    +
    + Python +
    +
    +
    +
    + 
    def get_score(card_or_deck: Card | Deck) -> int:
+    if is_deck_of_cards(card_or_deck):
+        # Calculate score of a deck of cards
+    ...
+
    +
    + +
    +
    +

    + Inside of the if block, the type checker knows that card_or_deck is, in fact, of the type Deck. See PEP 647 for more details. +

    +

    + The final new typing feature is Parameter Specification Variables, which is related to type variables. Consider the definition of a decorator. In general, it looks something like the following: +

    +
    +
    + Python +
    +
    +
    +
    + 
    import functools
+from typing import Any, Callable, TypeVar
+
+R = TypeVar("R")
+
+def decorator(func: Callable[..., R]) -> Callable[..., R]:
+    @functools.wraps(func)
+    def wrapper(*args: Any, **kwargs: Any) -> R:
+        ...
+    return wrapper
+
    +
    + +
    +
    +

    + The annotations mean that the function returned by the decorator is a callable with some parameters and the same return type, R, as the function passed into the decorator. The ellipsis (...) in the function header correctly allows any number of parameters, and each of those parameters can be of any type. However, there’s no validation that the returned callable has the same parameters as the function that was passed in. In practice, this means that type checkers aren’t able to check decorated functions properly. +

    +

    + Unfortunately, you can’t use TypeVar for the parameters because you don’t know how many parameters the function will have. In Python 3.10, you’ll have access to ParamSpec in order to type hint these kinds of callables properly. ParamSpec works similarly to TypeVar but stands in for several parameters at once. You can rewrite your decorator as follows to take advantage of ParamSpec: +

    +
    +
    + Python +
    +
    +
    +
    + 
    import functools
+from typing import Callable, ParamSpec, TypeVar
+
+P = ParamSpec("P")
+R = TypeVar("R")
+
+def decorator(func: Callable[P, R]) -> Callable[P, R]:
+    @functools.wraps(func)
+    def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
+        ...
+    return wrapper
+
    +
    + +
    +
    +

    + Note that you also use P when you annotate wrapper(). You can also use the new typing.Concatenate to add types to ParamSpec. See the documentation and PEP 612 for details and examples. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Stricter Zipping of Sequences +

    +

    + zip() is a built-in function in Python that can combine elements from several sequences. Python 3.10 introduces the new strict parameter, which adds a runtime test to check that all sequences being zipped have the same length. +

    +

    + As an example, consider the following table of Lego sets: +

    +
    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Name + + Set Number + + Pieces +
    + Louvre + + 21024 + + 695 +
    + Diagon Alley + + 75978 + + 5544 +
    + NASA Apollo Saturn V + + 92176 + + 1969 +
    + Millennium Falcon + + 75192 + + 7541 +
    + New York City + + 21028 + + 598 +
    +
    +

    + One way to represent these data in plain Python would be with each column as a list. It could look something like this: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> names = ["Louvre", "Diagon Alley", "Saturn V", "Millennium Falcon", "NYC"]
+>>> set_numbers = ["21024", "75978", "92176", "75192", "21028"]
+>>> num_pieces = [695, 5544, 1969, 7541, 598]
+
    +
    + +
    +
    +

    + Note that you have three independent lists, but there’s an implicit correspondence between their elements. The first name ("Louvre"), the first set number ("21024"), and the first number of pieces (695) all describe the first Lego set. +

    + +

    + zip() can be used to iterate over these three lists in parallel: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> for name, num, pieces in zip(names, set_numbers, num_pieces):
+...     print(f"{name} ({num}): {pieces} pieces")
+...
+Louvre (21024): 695 pieces
+Diagon Alley (75978): 5544 pieces
+Saturn V (92176): 1969 pieces
+Millennium Falcon (75192): 7541 pieces
+NYC (21028): 598 pieces
+
    +
    + +
    +
    +

    + Note how each line collects information from all three lists and shows information about one particular set. This is a very common pattern that’s used in a lot of different Python code, including in the standard library. +

    +

    + You can also add list() to collect the contents of all three lists in a single, nested list of tuples: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> list(zip(names, set_numbers, num_pieces))
+[('Louvre', '21024', 695),
+ ('Diagon Alley', '75978', 5544),
+ ('Saturn V', '92176', 1969),
+ ('Millennium Falcon', '75192', 7541),
+ ('NYC', '21028', 598)]
+
    +
    + +
    +
    +

    + Note how the nested list closely resembles the original table. +

    +

    + The dark side of using zip() is that it’s quite easy to introduce a subtle bug that can be hard to discover. Note what happens if there’s a missing item in one of your lists: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> set_numbers = ["21024", "75978", "75192", "21028"]  # Saturn V missing
+
+>>> list(zip(names, set_numbers, num_pieces))
+[('Louvre', '21024', 695),
+ ('Diagon Alley', '75978', 5544),
+ ('Saturn V', '75192', 1969),
+ ('Millennium Falcon', '21028', 7541)]
+
    +
    + +
    +
    +

    + All the information about the New York City set disappeared! Additionally, the set numbers for Saturn V and Millennium Falcon are wrong. If your datasets are bigger, these kinds of errors can be very hard to discover. And even when you observe that something’s wrong, it’s not always easy to diagnose and fix. +

    +

    + The issue is that you assumed that the three lists have the same number of elements and that the information is in the same order in each list. After set_numbers gets corrupted, this assumption is no longer true. +

    +

    + PEP 618 introduces a new strict keyword parameter to zip() that you can use to confirm all sequences have the same length. In your example, it would raise an error alerting you to the corrupted list: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> list(zip(names, set_numbers, num_pieces, strict=True))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+ValueError: zip() argument 2 is shorter than argument 1
+
    +
    + +
    +
    +

    + When the iteration reaches the New York City Lego set, the second argument set_numbers is already exhausted, while there are still elements left in the first argument names. Instead of silently giving the wrong result, your code fails with an error, and you can take action to find and fix the mistake. +

    +

    + There are use cases when you want to combine sequences of unequal length. Expand the box below to see how zip() and itertools.zip_longest() handle these: +

    +
    +
    +

    + +

    +
    +
    +
    +

    + The following idiom divides the Lego sets into pairs: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> num_per_group = 2
+>>> list(zip(*[iter(names)] * num_per_group))
+[('Louvre', 'Diagon Alley'), ('Saturn V', 'Millennium Falcon')]
+
    +
    + +
    +
    +

    + There are five sets, a number that doesn’t divide evenly into pairs. In this case, the default behavior of zip(), where the last element is dropped, might make sense. You could use strict=True here as well, but that would raise an error when your list can’t be split into pairs. A third option, which could be the best in this case, is to use zip_longest() from the itertools standard library. +

    +

    + As the name suggests, zip_longest() combines sequences until the longest sequence is exhausted. If you use zip_longest() to divide the Lego sets, it becomes more explicit that New York City doesn’t have any pairing: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> from itertools import zip_longest
+
+>>> list(zip_longest(*[iter(names)] * num_per_group, fillvalue=""))
+[('Louvre', 'Diagon Alley'),
+ ('Saturn V', 'Millennium Falcon'),
+ ('NYC', '')]
+
    +
    + +
    +
    +

    + Note that 'NYC' shows up in the last tuple together with an empty string. You can control what’s filled in for missing values with the fillvalue parameter. +

    +
    +
    +
    +

    + While strict is not really adding any new functionality to zip(), it can help you avoid those hard-to-find bugs. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + New Functions in the statistics Module +

    +

    + The statistics module was added to the standard library all the way back in 2014 with the release of Python 3.4. The intent of statistics is to make statistical calculations at the level of graphing calculators available in Python. +

    + +

    + Python 3.10 adds a few multivariable functions to statistics: +

    +
      +
    • + correlation() to calculate Pearson’s correlation coefficient for two variables +
      • +
    • + covariance() to calculate sample covariance for two variables +
      • +
    • + linear_regression() to calculate the slope and intercept in a linear regression +
      • +
    +

    + You can use each function to describe a certain aspect of the relationship between two variables. As an example, say that you have data from a set of blog posts—the number of words in each blog post and the number of views each post has had over some time period: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> words = [7742, 11539, 16898, 13447, 4608, 6628, 2683, 6156, 2623, 6948]
+>>> views = [8368, 5901, 3978, 3329, 2611, 2096, 1515, 1177, 814, 467]
+
    +
    + +
    +
    +

    + You now want to investigate whether there’s any (linear) relationship between the number of words and number of views. In Python 3.10, you can calculate the correlation between words and views with the new correlation() function: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import statistics
+
+>>> statistics.correlation(words, views)
+0.454180067865917
+
    +
    + +
    +
    +

    + The correlation between two variables is always a number between -1 and 1. If it’s close to 0, then there’s little correspondence between them, while a correlation close to -1 or 1 indicates that the behaviors of the two variables tend to follow each other. In this example, a correlation of 0.45 indicates that there’s a tendency for posts with more words to have more views, although it’s not a strong connection. +

    + +

    + You can also calculate the covariance between words and views. The covariance is another measure of the joint variability between two variables. You can calculate it with covariance(): +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import statistics
+
+>>> statistics.covariance(words, views)
+5292289.977777777
+
    +
    + +
    +
    +

    + In contrast to correlation, covariance is an absolute measure. It should be interpreted in the context of the variability within the variables themselves. In fact, you can normalize the covariance by the standard deviation of each variable to recover Pearson’s correlation coefficient: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import statistics
+
+>>> cov = statistics.covariance(words, views)
+>>> σ_words, σ_views = statistics.stdev(words), statistics.stdev(views)
+>>> cov / (σ_words * σ_views)
+0.454180067865917
+
    +
    + +
    +
    +

    + Note that this matches your earlier correlation coefficient exactly. +

    +

    + A third way of looking at the linear correspondence between the two variables is through simple linear regression. You do the linear regression by calculating two numbers, slope and intercept, so that the (squared) error is minimized in the approximation number of views = slope × number of words + intercept. +

    +

    + In Python 3.10, you can use linear_regression(): +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import statistics
+
+>>> statistics.linear_regression(words, views)
+LinearRegression(slope=0.2424443064354672, intercept=1103.6954940247645)
+
    +
    + +
    +
    +

    + Based on this regression, a post with 10,074 words could expect about 0.2424 × 10074 + 1104 = 3546 views. However, as you saw earlier, the correlation between the number of words and the number of views is quite weak. Therefore, you shouldn’t expect this prediction to be very accurate. +

    +

    + The LinearRegression object is a named tuple. This means that you can unpack the slope and intercept directly: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import statistics
+
+>>> slope, intercept = statistics.linear_regression(words, views)
+>>> slope * 10074 + intercept
+3546.0794370556605
+
    +
    + +
    +
    +

    + Here, you use slope and intercept to predict the number of views on a blog post with 10,074 words. +

    +

    + You still want to use some of the more advanced packages like pandas and statsmodels if you do a lot of statistical analysis. With the new additions to statistics in Python 3.10, however, you have the chance to do basic analysis more easily without bringing in third-party dependencies. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Other Pretty Cool Features +

    +

    + So far, you’ve seen the biggest and most impactful new features in Python 3.10. In this section, you’ll get a glimpse of a few of the other changes that the new version brings along. If you’re curious about all the changes made for this new version, check out the documentation. +

    +
    +

    + Default Text Encodings +

    +

    + When you open a text file, the default encoding used to interpret the characters is system dependent. In particular, locale.getpreferredencoding() is used. On Mac and Linux, this usually returns "UTF-8", while the result on Windows is more varied. +

    +

    + You should therefore always specify an encoding when you attempt to open a text file: +

    +
    +
    + Python +
    +
    +
    +
    + 
    with open("some_file.txt", mode="r", encoding="utf-8") as file:
+    ...  # Do something with file
+
    +
    + +
    +
    +

    + If you don’t explicitly specify an encoding, the preferred locale encoding is used, and you could experience that a file that can be read on one computer fails to open on another. +

    +

    + Python 3.7 introduced UTF-8 mode, which allows you to force your programs to use UTF-8 encoding independent of the locale encoding. You can enable UTF-8 mode by giving the -X utf8 command-line option to the python executable or by setting the PYTHONUTF8 environment variable. +

    +

    + In Python 3.10, you can activate a warning that will tell you when a text file is opened without a specified encoding. Consider the following script, which doesn’t specify an encoding: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # mirror.py
+
+import pathlib
+import sys
+
+def mirror_file(filename):
+    for line in pathlib.Path(filename).open(mode="r"):
+        print(f"{line.rstrip()[::-1]:>72}")
+
+if __name__ == "__main__":
+    for filename in sys.argv[1:]:
+        mirror_file(filename)
+
    +
    + +
    +
    +

    + The program will echo one or more text files back to the console, but with each line reversed. Run the program on itself with the encoding warning enabled: +

    +
    +
    + Shell +
    + + +
    +
    +
    +
    + 
    $ python -X warn_default_encoding mirror.py mirror.py
+/home/rp/mirror.py:7: EncodingWarning: 'encoding' argument not specified
+  for line in pathlib.Path(filename).open(mode="r"):
+                                                             yp.rorrim #
+
+                                                          bilhtap tropmi
+                                                              sys tropmi
+
+                                              :)emanelif(elif_rorrim fed
+                  :)"r"=edom(nepo.)emanelif(htaP.bilhtap ni enil rof
+                             )"}27>:]1-::[)(pirtsr.enil{"f(tnirp
+
+                                              :"__niam__" == __eman__ fi
+                                       :]:1[vgra.sys ni emanelif rof
+                                           )emanelif(elif_rorrim
+
    +
    + +
    +
    +

    + Note the EncodingWarning printed to the console. The command-line option -X warn_default_encoding activates it. The warning will disappear if you specify an encoding—for example, encoding="utf-8"—when you open the file. +

    +

    + There are times when you want to use the user-defined local encoding. You can still do so by explicitly using encoding="locale". However, it’s recommended to use UTF-8 whenever possible. You can check out PEP 597 for more information. +

    +
    +
    +

    + Asynchronous Iteration +

    +

    + Asynchronous programming is a powerful programming paradigm that’s been available in Python since version 3.5. You can recognize an asynchronous program by its use of the async keyword or special methods that start with .__a like .__aiter__() or .__aenter__(). +

    +

    + In Python 3.10, two new asynchronous built-in functions are added: aiter() and anext(). In practice, these functions call the .__aiter__() and .__anext__() special methods—analogous to the regular iter() and next()—so no new functionality is added. These are convenience functions that make your code more readable. +

    +

    + In other words, in the newest version of Python, the following statements—where things is an asynchronous iterable—are equivalent: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> it = things.__aiter__()
+>>> it = aiter(things)
+
    +
    + +
    +
    +

    + In either case, it ends up as an asynchronous iterator. Expand the following box to see a complete example using aiter() and anext(): +

    +
    +
    +

    + +

    +
    +
    +
    +

    + The following program counts the number of lines in several files. In practice, you use Python’s ability to iterate over files to count the number of lines. The script uses asynchronous iteration in order to handle several files concurrently. +

    +

    + Note that you need to install the third-party aiofiles package with pip before running this code: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # line_count.py
+
+import asyncio
+import sys
+import aiofiles
+
+async def count_lines(filename):
+    """Count the number of lines in the given file"""
+    num_lines = 0
+
+    async with aiofiles.open(filename, mode="r") as file:
+        lines = aiter(file)
+        while True:
+            try:
+                await anext(lines)
+                num_lines += 1
+            except StopAsyncIteration:
+                break
+
+    print(f"{filename}: {num_lines}")
+
+async def count_all_files(filenames):
+    """Asynchronously count lines in all files"""
+    tasks = [asyncio.create_task(count_lines(f)) for f in filenames]
+    await asyncio.gather(*tasks)
+
+if __name__ == "__main__":
+    asyncio.run(count_all_files(filenames=sys.argv[1:]))
+
    +
    + +
    +
    +

    + asyncio is used to create and run one asynchronous task per filename. count_lines() opens one file asynchronously and iterates through it using aiter() and anext() in order to count the number of lines. +

    +
    +
    +
    +

    + See PEP 525 to learn more about asynchronous iteration. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Context Manager Syntax +

    +

    + Context managers are great for managing resources in your programs. Until recently, though, their syntax has included an uncommon wart. You haven’t been allowed to use parentheses to break long with statements like this: +

    +
    +
    + Python +
    +
    +
    +
    + 
    with (
+    read_path.open(mode="r", encoding="utf-8") as read_file,
+    write_path.open(mode="w", encoding="utf-8") as write_file,
+):
+    ...
+
    +
    + +
    +
    +

    + In earlier versions of Python, this causes an invalid syntax error message. Instead, you need to use a backslash (\) if you want to control where you break your lines: +

    +
    +
    + Python +
    +
    +
    +
    + 
    with read_path.open(mode="r", encoding="utf-8") as read_file, \
+     write_path.open(mode="w", encoding="utf-8") as write_file:
+    ...
+
    +
    + +
    +
    +

    + While explicit line continuation with backslashes is possible in Python, PEP 8 discourages it. The Black formatting tool avoids backslashes completely. +

    +

    + In Python 3.10, you’re now allowed to add parentheses around with statements to your heart’s content. Especially if you’re employing several context managers at once, like in the example above, this can help improve the readability of your code. Python’s documentation shows a few other possibilities with this new syntax. +

    +

    + One small fun fact: parenthesized with statements actually work in version 3.9 of CPython. Their implementation came almost for free with the introduction of the PEG parser in Python 3.9. The reason that this is called a Python 3.10 feature is that using the PEG parser is voluntary in Python 3.9, while Python 3.9, with the old LL(1) parser, doesn’t support parenthesized with statements. +

    +
    +
    +

    + Modern and Secure SSL +

    +

    + Security can be challenging! A good rule of thumb is to avoid rolling your own security algorithms and instead rely on established packages. +

    +

    + Python uses OpenSSL for different cryptographic features that are exposed in the hashlib, hmac, and ssl standard library modules. Your system can manage OpenSSL, or a Python installer can include OpenSSL. +

    +

    + Python 3.9 supports using any of the OpenSSL versions 1.0.2 LTS, 1.1.0, and 1.1.1 LTS. Both OpenSSL 1.0.2 LTS and OpenSSL 1.1.0 are past their lifetime, so Python 3.10 will only support OpenSSL 1.1.1 LTS, as described in the following table: +

    +
    + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
    + Open SSL version + + Python 3.9 + + Python 3.10 + + End-of-life +
    + 1.0.2 LTS + + ✔ + + ✖ + + December 20, 2019 +
    + 1.1.0 + + ✔ + + ✖ + + September 10, 2019 +
    + 1.1.1 LTS + + ✔ + + ✔ + + September 11, 2023 +
    +
    +

    + This end of support for older versions will only affect you if you need to upgrade the system Python on an older operating system. If you use macOS or Windows, or if you install Python from python.org or use (Ana)Conda, you’ll see no change. +

    +

    + However, Ubuntu 18.04 LTS uses OpenSSL 1.1.0, while Red Hat Enterprise Linux (RHEL) 7 and CentOS 7 both use OpenSSL 1.0.2 LTS. If you need to run Python 3.10 on these systems, you should look at installing it yourself using either the python.org or Conda installer. +

    +

    + Dropping support for older versions of OpenSSL will make Python more secure. It’ll also help the Python developers in that code will be easier to maintain. Ultimately, this helps you because your Python experience will be more robust. See PEP 644 for more details. +

    +
    +
    +

    + More Information About Your Python Interpreter +

    +

    + The sys module contains a lot of information about your system, the current Python runtime, and the script currently being executed. You can, for example, inquire about the paths where Python looks for modules with sys.path and see all modules that have been imported in the current session with sys.modules. +

    +

    + In Python 3.10, sys has two new attributes. First, you can now get a list of the names of all modules in the standard library: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import sys
+
+>>> len(sys.stdlib_module_names)
+302
+
+>>> sorted(sys.stdlib_module_names)[-5:]
+['zipapp', 'zipfile', 'zipimport', 'zlib', 'zoneinfo']
+
    +
    + +
    +
    +

    + Here, you can see that there are around 300 modules in the standard library, several of which start with the letter z. Note that only top-level modules and packages are listed. Subpackages like importlib.metadata don’t get a separate entry. +

    +

    + You will probably not be using sys.stdlib_module_names all that often. Still, the list ties in nicely with similar introspection features like keyword.kwlist and sys.builtin_module_names. +

    +

    + One possible use case for the new attribute is to identify which of the currently imported modules are third-party dependencies: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import pandas as pd
+>>> import sys
+
+>>> {m for m in sys.modules if "." not in m} - sys.stdlib_module_names
+{'__main__', 'numpy', '_cython_0_29_24', 'dateutil', 'pytz',
+ 'six', 'pandas', 'cython_runtime'}
+
    +
    + +
    +
    +

    + You find the imported top-level modules by looking at names in sys.modules that don’t have a dot in their name. By comparing them to the standard library module names, you find that numpy, dateutil, and pandas are some of the imported third-party modules in this example. +

    +

    + The other new attribute is sys.orig_argv. This is related to sys.argv, which holds the command-line arguments given to your program when it was started. In contrast, sys.orig_argv lists the command-line arguments passed to the python executable itself. Consider the following example: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # argvs.py
+
+import sys
+
+print(f"argv: {sys.argv}")
+print(f"orig_argv: {sys.orig_argv}")
+
    +
    + +
    +
    +

    + This script echoes back the orig_argv and argv lists. Run it to see how the information is captured: +

    +
    +
    + Shell +
    + + +
    +
    +
    +
    + 
    $ python -X utf8 -O argvs.py 3.10 --upgrade
+argv: ['argvs.py', '3.10', '--upgrade']
+orig_argv: ['python', '-X', 'utf8', '-O', 'argvs.py', '3.10', '--upgrade']
+
    +
    + +
    +
    +

    + Essentially, all arguments—including the name of the Python executable—end up in orig_argv. This is in contrast to argv, which only contains the arguments that aren’t handled by python itself. +

    +

    + Again, this is not a feature that you’ll use a lot. If your program needs to concern itself with how it’s being run, you’re usually better off relying on information that’s already exposed instead of trying to parse this list. For example, you can choose to use the strict zip() mode only when your script is not running with the optimized flag, -O, like this: +

    +
    +
    + Python +
    +
    +
    +
    + 
    list(zip(names, set_numbers, num_pieces, strict=__debug__))
+
    +
    + +
    +
    +

    + The __debug__ flag is set when the interpreter starts. It’ll be False if you’re running python with -O or -OO specified, and True otherwise. Using __debug__ is usually preferable to "-O" not in sys.orig_argv or some similar construct. +

    +

    + One of the motivating use cases for sys.orig_argv is that you can use it to spawn a new Python process with the same or modified command-line arguments as your current process. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + Future Annotations +

    +

    + Annotations were introduced in Python 3 to give you a way to attach metadata to variables, function parameters, and return values. They are most commonly used to add type hints to your code. +

    +

    + One challenge with annotations is that they must be valid Python code. For one thing, this makes it hard to type hint recursive classes. PEP 563 introduced postponed evaluation of annotations, making it possible to annotate with names that haven’t yet been defined. Since Python 3.7, you can activate postponed evaluation of annotations with a __future__ import: +

    +
    +
    + Python +
    +
    +
    +
    + 
    from __future__ import annotations
+
    +
    + +
    +
    +

    + The intention was that postponed evaluation would become the default at some point in the future. After the 2020 Python Language Summit, it was decided to make this happen in Python 3.10. +

    +

    + However, after more testing, it became clear that postponed evaluation didn’t work well for projects that use annotations at runtime. Key people in the FastAPI and the Pydantic projects voiced their concerns. At the last minute, it was decided to reschedule these changes for Python 3.11. +

    +

    + To ease the transition into future behavior, a few changes have been made in Python 3.10 as well. Most importantly, a new inspect.get_annotations() function has been added. You should call this to access annotations at runtime: +

    +
    +
    + Python +
    + + +
    +
    +
    +
    + 
    >>> import inspect
+
+>>> def mean(numbers: list[int | float]) -> float:
+...     return sum(numbers) / len(numbers)
+...
+
+>>> inspect.get_annotations(mean)
+{'numbers': list[int | float], 'return': <class 'float'>}
+
    +
    + +
    +
    +

    + Check out Annotations Best Practices for details. +

    +
    +
    +
    +

    + How to Detect Python 3.10 at Runtime +

    +

    + Python 3.10 is the first version of Python with a two-digit minor version number. While this is mostly an interesting fun fact and an indication that Python 3 has been around for quite some time, it does also have some practical consequences. +

    +

    + When your code needs to do something specific based on the version of Python at runtime, you’ve gotten away with doing a lexicographical comparison of version strings until now. While it’s never been good practice, it’s been possible to do the following: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # bad_version_check.py
+
+import sys
+
+# Don't do the following
+if sys.version < "3.6":
+    raise SystemExit("Only Python 3.6 and above is supported")
+
    +
    + +
    +
    +

    + In Python 3.10, this code will raise SystemExit and stop your program. This happens because, as strings, "3.10" is less than "3.6". +

    +

    + The correct way to compare version numbers is to use tuples of numbers: +

    +
    +
    + Python +
    +
    +
    +
    + 
    # good_version_check.py
+
+import sys
+
+if sys.version_info < (3, 6):
+    raise SystemExit("Only Python 3.6 and above is supported")
+
    +
    + +
    +
    +

    + sys.version_info is a tuple object you can use for comparisons. +

    +

    + If you’re doing these kinds of comparisons in your code, you should check your code with flake8-2020 to make sure you’re handling versions correctly: +

    +
    +
    + Shell +
    + + +
    +
    +
    +
    + 
    $ python -m pip install flake8-2020
+
+$ flake8 bad_version_check.py good_version_check.py
+bad_version_check.py:3:4: YTT103 `sys.version` compared to string
+                          (python3.10), use `sys.version_info`
+
    +
    + +
    +
    +

    + With the flake8-2020 extension activated, you’ll get a recommendation about replacing sys.version with sys.version_info. +

    +
    +
    +
    +
    + +
    +
    + Remove ads +
    +
    +
    +

    + So, Should You Upgrade to Python 3.10? +

    +

    + You’ve now seen the coolest features of the newest and latest version of Python. The question now is whether you should upgrade to Python 3.10, and if yes, when you should do so. There are two different aspects to consider when thinking about upgrading to Python 3.10: +

    +
      +
    1. Should you upgrade your environment so that you run your code with the Python 3.10 interpreter? +
      2. +
    2. Should you write your code using the new Python 3.10 features? +
      3. +
    +

    + Clearly, if you want to test out structural pattern matching or any of the other cool new features you’ve read about here, you need Python 3.10. It’s possible to install the latest version side by side with your current Python version. A straightforward way to do this is to use an environment manager like pyenv or Conda. You can also use Docker to run Python 3.10 without installing it locally. +

    +

    + Python 3.10 has been through about five months of beta testing, so there shouldn’t be any big issues with starting to use it for your own development. You may find that some of your dependencies don’t immediately have wheels for Python 3.10 available, which makes them more cumbersome to install. But in general, using the newest Python for local development is fairly safe. +

    +

    + As always, you should be careful before upgrading your production environment. Be vigilant about testing that your code runs well on the new version. In particular, you want to be on the lookout for features that are deprecated or removed. +

    +

    + Whether you can start using the new features in your code or not depends on your user base and the environment where your code is running. If you can guarantee that Python 3.10 is available, then there’s no danger in using the new union type syntax or any other new feature. +

    +

    + If you’re distributing an app or a library that’s used by others instead, you may want to be a bit more conservative. Currently, Python 3.6 is the oldest officially supported Python version. It reaches end-of-life in December 2021, after which Python 3.7 will be the minimum supported version. +

    +

    + The documentation includes a useful guide about porting your code to Python 3.10. Check it out for more details! +

    +
    +
    +

    + Conclusion +

    +

    + The release of a new Python version is always worth celebrating. Even if you can’t start using the new features right away, they’ll become broadly available and part of your daily life within a few years. +

    +

    + In this tutorial, you’ve seen new features like: +

    +
      +
    • Friendlier error messages +
      • +
    • Powerful structural pattern matching +
      • +
    • + Type hint improvements +
      • +
    • Safer combination of sequences +
      • +
    • New statistics functions +
      • +
    +

    + For more Python 3.10 tips and a discussion with members of the Real Python team, check out Real Python Podcast Episode #81. +

    +

    + Have fun trying out the new features! Share your experiences in the comments below. +

    +
    +
    +
    + +
    +
    + + + +
    +
    +
    +

    + + Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Cool New Features in Python 3.10 +

    +
    +
    +
    +

    + 🐍 Python Tricks 💌 +

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    + Get a short & sweet Python Trick delivered to your inbox every couple of days. No spam ever. Unsubscribe any time. Curated by the Real Python team. +

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    +

    + About Geir Arne Hjelle +

    +
    +
    +
    +
    + Geir Arne Hjelle Geir Arne Hjelle +
    +
    +

    + Geir Arne is an avid Pythonista and a member of the Real Python tutorial team. +

    » More about Geir Arne +
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    + Each tutorial at Real Python is created by a team of developers so that it meets our high quality standards. The team members who worked on this tutorial are: +

    +
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    + Related Tutorial Categories: intermediate python +

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    + Recommended Video Course: Cool New Features in Python 3.10 +

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    + + diff --git a/packages/readabilityjs/test/test-pages/realpython/url.txt b/packages/readabilityjs/test/test-pages/realpython/url.txt new file mode 100644 index 000000000..852b2800d --- /dev/null +++ b/packages/readabilityjs/test/test-pages/realpython/url.txt @@ -0,0 +1 @@ +https://realpython.com/python310-new-features/ \ No newline at end of file diff --git a/packages/rss-handler/test/index.test.ts b/packages/rss-handler/test/index.test.ts index b43cf7973..f5c7b7b38 100644 --- a/packages/rss-handler/test/index.test.ts +++ b/packages/rss-handler/test/index.test.ts @@ -7,17 +7,17 @@ describe('isOldItem', () => { const item = { pubDate: '2020-01-01', } as RssFeedItem - const lastFetchedAt = Date.now() + const mostRecentItemTimestamp = Date.now() - expect(isOldItem(item, lastFetchedAt)).to.be.true + expect(isOldItem(item, mostRecentItemTimestamp)).to.be.true }) it('returns true if item was published at the last fetched time', () => { - const lastFetchedAt = Date.now() + const mostRecentItemTimestamp = Date.now() const item = { - pubDate: new Date(lastFetchedAt).toISOString(), + pubDate: new Date(mostRecentItemTimestamp).toISOString(), } as RssFeedItem - expect(isOldItem(item, lastFetchedAt)).to.be.true + expect(isOldItem(item, mostRecentItemTimestamp)).to.be.true }) }) diff --git a/packages/rule-handler/src/label.ts b/packages/rule-handler/src/label.ts index 9d3254ca6..16d9fe765 100644 --- a/packages/rule-handler/src/label.ts +++ b/packages/rule-handler/src/label.ts @@ -30,7 +30,7 @@ export const setLabels = async ( }) try { - return axios.post(`${apiEndpoint}/graphql`, data, { + return await axios.post(`${apiEndpoint}/graphql`, data, { headers: { Cookie: `auth=${auth};`, 'Content-Type': 'application/json', diff --git a/packages/rule-handler/src/notification.ts b/packages/rule-handler/src/notification.ts index 092f2440e..bddc1c28e 100644 --- a/packages/rule-handler/src/notification.ts +++ b/packages/rule-handler/src/notification.ts @@ -29,7 +29,7 @@ export const sendNotification = async ( } try { - return axios.post(`${apiEndpoint}/notification/send`, requestData, { + return await axios.post(`${apiEndpoint}/notification/send`, requestData, { headers: { Cookie: `auth=${auth};`, 'Content-Type': 'application/json', diff --git a/packages/rule-handler/src/page.ts b/packages/rule-handler/src/page.ts index 9070f7192..e91bc0173 100644 --- a/packages/rule-handler/src/page.ts +++ b/packages/rule-handler/src/page.ts @@ -27,7 +27,7 @@ export const archivePage = async ( }) try { - return axios.post(`${apiEndpoint}/graphql`, data, { + return await axios.post(`${apiEndpoint}/graphql`, data, { headers: { Cookie: `auth=${auth};`, 'Content-Type': 'application/json', @@ -66,7 +66,7 @@ export const markPageAsRead = async ( }) try { - return axios.post(`${apiEndpoint}/graphql`, data, { + return await axios.post(`${apiEndpoint}/graphql`, data, { headers: { Cookie: `auth=${auth};`, 'Content-Type': 'application/json', diff --git a/packages/web/components/templates/article/HighlightNoteModal.tsx b/packages/web/components/templates/article/HighlightNoteModal.tsx index d2bab8fb5..c505f96b3 100644 --- a/packages/web/components/templates/article/HighlightNoteModal.tsx +++ b/packages/web/components/templates/article/HighlightNoteModal.tsx @@ -78,6 +78,13 @@ export function HighlightNoteModal( event.preventDefault() event.stopPropagation() }} + onKeyDown={(event) => { + if ((event.metaKey || event.ctrlKey) && event.key === 'Enter') { + event.preventDefault() + saveNoteChanges() + props.onOpenChange(false) + } + }} >
    { diff --git a/packages/web/components/tokens/stitches.config.ts b/packages/web/components/tokens/stitches.config.ts index 4442c1083..2e82e9c68 100644 --- a/packages/web/components/tokens/stitches.config.ts +++ b/packages/web/components/tokens/stitches.config.ts @@ -169,7 +169,7 @@ export const { styled, css, theme, getCssText, globalCss, keyframes, config } = thBackground3: '#FFFFFF', thBackground4: '#EBEBEB', thBackground5: '#F5F5F5', - thBackgroundActive: '#F9F9F9', + thBackgroundActive: '#FFEA9F', thBackgroundContrast: '#FFFFFF', thLeftMenuBackground: '#FCFCFC', thLibraryBackground: '#F3F3F3', @@ -281,7 +281,7 @@ const darkThemeSpec = { thBackground3: '#242424', thBackground4: '#3D3D3D', thBackground5: '#3D3D3D', - thBackgroundActive: '#2E2E2E', + thBackgroundActive: '#3D3D3D', thBackgroundContrast: '#000000', thLeftMenuBackground: '#1D1D1D', thLibraryBackground: '#333333', diff --git a/pkg/bull-queue-admin/index.js b/pkg/bull-queue-admin/index.js index 57fe2a4b9..fee71ed8f 100644 --- a/pkg/bull-queue-admin/index.js +++ b/pkg/bull-queue-admin/index.js @@ -105,8 +105,8 @@ const run = async () => { serverAdapter.getRouter() ) - app.listen(8080, () => { - console.log('Running on 8080...') + app.listen(process.env.PORT ?? 8080, () => { + console.log(`Running on ${process.env.PORT ?? 8080}...`) }) } diff --git a/pkg/bull-queue-admin/package.json b/pkg/bull-queue-admin/package.json index 29b7505e1..a04a8b00f 100644 --- a/pkg/bull-queue-admin/package.json +++ b/pkg/bull-queue-admin/package.json @@ -8,7 +8,7 @@ "test": "echo \"Error: no test specified\" && exit 1" }, "dependencies": { - "@bull-board/express": "^3.10.4", + "@bull-board/express": "^5.9.0", "body-parser": "^1.20.2", "bullmq": "^4.6.0", "connect-ensure-login": "^0.1.1", diff --git a/pkg/bull-queue-admin/yarn.lock b/pkg/bull-queue-admin/yarn.lock index 081e5971c..eb889b4de 100644 --- a/pkg/bull-queue-admin/yarn.lock +++ b/pkg/bull-queue-admin/yarn.lock @@ -2,29 +2,29 @@ # yarn lockfile v1 -"@bull-board/api@3.11.1": - version "3.11.1" - resolved "https://registry.npmjs.org/@bull-board/api/-/api-3.11.1.tgz" - integrity sha512-ElwX7sM+Ng4ZL9KUsbDubRE+r2hu/gss85OsROeE9bmyfkW14jOJkgr5MKUyjTTgPEeMs1Mw55TgQs2vxoWBiA== +"@bull-board/api@5.13.0": + version "5.13.0" + resolved "https://registry.yarnpkg.com/@bull-board/api/-/api-5.13.0.tgz#119dcb675555537b9a90d59294a3c093b02afac7" + integrity sha512-v5wvnGim1pmSK9PR1RYSx1dsCW6sOQYJnpvRgU6HZbVbW/5Z0luUBGpYYxM2Ry98uYKeU999mbS7xjunOkAQDw== dependencies: redis-info "^3.0.8" -"@bull-board/express@^3.10.4": - version "3.11.1" - resolved "https://registry.npmjs.org/@bull-board/express/-/express-3.11.1.tgz" - integrity sha512-+a5IQilu/CxvnGC0z6oJPANn7eF/Q61VU86JR9vRtmaY96mKKny0NuAyulJ2/Y9JznMCBOLUsXWL6fm9zD9kJw== +"@bull-board/express@^5.9.0": + version "5.13.0" + resolved "https://registry.yarnpkg.com/@bull-board/express/-/express-5.13.0.tgz#29f2c0a61d6206c13e8816b9d0f79bf06c92064f" + integrity sha512-KWI+nGLkZ1rLsOnjHvR7DdeP371l9Fr7narG0ygn78pybR5vAdcHXWde0Uusmm80JyM0nN1JOiqrhMp3mJH7NA== dependencies: - "@bull-board/api" "3.11.1" - "@bull-board/ui" "3.11.1" - ejs "3.1.7" - express "4.17.3" + "@bull-board/api" "5.13.0" + "@bull-board/ui" "5.13.0" + ejs "^3.1.7" + express "^4.17.3" -"@bull-board/ui@3.11.1": - version "3.11.1" - resolved "https://registry.npmjs.org/@bull-board/ui/-/ui-3.11.1.tgz" - integrity sha512-SRrfvxHF/WaBICiAFuWAoAlTvoBYUBmX94oRbSKzVILRFZMe3gs0hN071BFohrn4yOTFHAkWPN7cjMbaqHwCag== +"@bull-board/ui@5.13.0": + version "5.13.0" + resolved "https://registry.yarnpkg.com/@bull-board/ui/-/ui-5.13.0.tgz#b0f1a5a0e446c608b4c6c29bb5d866c05c9c8bd7" + integrity sha512-UZ88j0c/G/UI5+F3zh6If9LqgF4kMmvRmTgnNckm8HJbclUdqvrcHBpo/e0HfdCaWGGhI2Gc12hq+AECc6c4Sw== dependencies: - "@bull-board/api" "3.11.1" + "@bull-board/api" "5.13.0" "@ioredis/commands@^1.1.1": version "1.2.0" @@ -96,22 +96,6 @@ balanced-match@^1.0.0: resolved "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz" integrity sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw== -body-parser@1.19.2: - version "1.19.2" - resolved "https://registry.npmjs.org/body-parser/-/body-parser-1.19.2.tgz" - integrity sha512-SAAwOxgoCKMGs9uUAUFHygfLAyaniaoun6I8mFY9pRAJL9+Kec34aU+oIjDhTycub1jozEfEwx1W1IuOYxVSFw== - dependencies: - bytes "3.1.2" - content-type "~1.0.4" - debug "2.6.9" - depd "~1.1.2" - http-errors "1.8.1" - iconv-lite "0.4.24" - on-finished "~2.3.0" - qs "6.9.7" - raw-body "2.4.3" - type-is "~1.6.18" - body-parser@1.20.1: version "1.20.1" resolved "https://registry.npmjs.org/body-parser/-/body-parser-1.20.1.tgz" @@ -294,30 +278,20 @@ depd@2.0.0, depd@~2.0.0: resolved "https://registry.npmjs.org/depd/-/depd-2.0.0.tgz" integrity sha512-g7nH6P6dyDioJogAAGprGpCtVImJhpPk/roCzdb3fIh61/s/nPsfR6onyMwkCAR/OlC3yBC0lESvUoQEAssIrw== -depd@~1.1.2: - 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version "4.17.3" - resolved "https://registry.npmjs.org/express/-/express-4.17.3.tgz" - integrity sha512-yuSQpz5I+Ch7gFrPCk4/c+dIBKlQUxtgwqzph132bsT6qhuzss6I8cLJQz7B3rFblzd6wtcI0ZbGltH/C4LjUg== - dependencies: - accepts "~1.3.8" - array-flatten "1.1.1" - body-parser "1.19.2" - content-disposition "0.5.4" - content-type "~1.0.4" - cookie "0.4.2" - cookie-signature "1.0.6" - debug "2.6.9" - depd "~1.1.2" - encodeurl "~1.0.2" - escape-html "~1.0.3" - etag "~1.8.1" - finalhandler "~1.1.2" - fresh "0.5.2" - merge-descriptors "1.0.1" - methods "~1.1.2" - on-finished "~2.3.0" - parseurl "~1.3.3" - path-to-regexp "0.1.7" - proxy-addr "~2.0.7" - qs "6.9.7" - range-parser "~1.2.1" - safe-buffer "5.2.1" - send "0.17.2" - serve-static "1.14.2" - setprototypeof "1.2.0" - statuses "~1.5.0" - type-is "~1.6.18" - utils-merge "1.0.1" - vary "~1.1.2" - express@^4.17.3: version "4.18.2" resolved "https://registry.npmjs.org/express/-/express-4.18.2.tgz" @@ -443,19 +381,6 @@ finalhandler@1.2.0: statuses "2.0.1" unpipe "~1.0.0" -finalhandler@~1.1.2: - 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