Kuyerekezera kwa Python Type Checker: Empty Container Inference

Chifukwa Chake Zotengera Zopanda Zake Zimaphwanya Ma Checkers a Python - Ndi Zomwe Mungachitire Pazo

Dongosolo lolemba pang'onopang'ono la Python lakhwima kwambiri kuyambira pomwe PEP 484 idakhazikitsa zolozera zamtundu mu 2015. Masiku ano, opanga mamiliyoni ambiri amadalira ma static type checkers kuti agwire nsikidzi asanayambe kupanga. Koma pali ngodya yobisika, yokhumudwitsa yamtundu wamtundu womwe umayenderabe ngakhale mainjiniya odziwa zambiri: chotengera chopanda kanthu chimakhala ndi mtundu wanji? Mukalemba x = [] popanda mawu, chowunikira chamtundu wanu chiyenera kuganiza - ndi ma checkers osiyanasiyana amalingalira mosiyana. Kusiyanaku kumabweretsa mavuto enieni kwa magulu omwe amasunga ma codebase akulu, pomwe kusintha kapena kuphatikiza zoyang'anira mitundu kumatha kuwonetsa zolakwika zambiri zosayembekezereka usiku umodzi.

Nkhaniyi ikufotokoza momwe ma chekeni anayi amtundu wa Python - mypy, pyright, pytype, ndi pyre - amagwirira ntchito zotengera zopanda kanthu, chifukwa chake sagwirizana, ndi njira zotani zomwe mungatsatire kuti mulembe Python yotetezedwa mosasamala kanthu komwe mwasankha.

Vuto Lalikulu: Zotengera Zopanda Zachinthu Ndizosamveka Mwachibadwa

Ganizirani za mzere wosalakwa wa Python: zotsatira = []. Kodi zotsatira ndi mndandanda[int]? Amndandanda[str]? Amndandanda[dict[str, Any]]? Popanda mawu owonjezera, palibe njira yodziwira. Nthawi yothamanga ya Python sichisamala - mindandanda ndi yosiyana kwambiri ndi chilengedwe - koma ofufuza amtundu wa static ayenera kupatsa mtundu wa konkire kumitundu iliyonse kuti igwire ntchito yawo. Izi zimapanga kukangana kwakukulu pakati pa kusinthasintha kwa Python ndi zitsimikizo zomwe kusanthula kokhazikika kumayesa kupereka.

Vutoli limakhala ndi madikishonale ndi ma seti. Zopanda kanthu {} zimagawidwa ngati dict, osati seti, zomwe zimawonjezera kusamveka bwino pamwamba pa mtundu wa kusamveka bwino. Ndipo zotengera zomwe zasungidwa - ganizirani defaultdict(mndandanda) kapena zotsatira = {k: [] za k mu makiyi} - kukankhira mainjini otengera malire awo. Chowunikira chilichonse chapanga ma heuristics akeake, ndipo kusiyana kwake kuli kofunika kwambiri kuposa momwe opanga ambiri amaganizira.

Mukapangidwe kazinthu zokonza zochulukira zenizeni - kaya ndi CRM yomwe imagwira ma rekodi a kasitomala, gawo la ma invoice opanga zinthu, kapena ma analytics aggregating metrics - zotengera zopanda kanthu zimawoneka nthawi zonse ngati njira zoyambira. Kulakwitsa kwa mitundu yawo sikumangotulutsa machenjezo a linter; imatha kubisa zolakwika zenizeni zomwe zimadutsa mpaka nthawi yothamanga.

Mypy: Chidziwitso Choyimitsidwa Ndi Chilichonse

Mypy, chowunikira chakale kwambiri komanso chodziwika bwino cha Python, chimatenga njira yochepetsera zotengera zopanda kanthu. Ikakumana ndi x = [] pakukula kwa ntchito, imayesa kulepheretsa chisankho chamtundu ndikuwonetsa mtundu wa chinthucho kuchokera pakugwiritsa ntchito motsatira. Ngati mulemba x = [] kutsatiridwa ndi x.append(42), mypy idzafotokoza mndandanda[int]. Njira ya "kujowina" iyi imagwira ntchito modabwitsa pamilandu yowongoka pomwe chidebecho chili ndi anthu ofanana.

Komabe, machitidwe a mypy amasintha kwambiri kutengera zomwe zikuchitika komanso makonda. Pa module scope (code-level code), kapena chidebecho chikaperekedwa ku ntchito ina musanakhazikitsidwe, mypy nthawi zambiri imabwerera ku mndandanda[Aliyense]. Pansi pa --strict mbendera, izi zimabweretsa cholakwika, koma mumachitidwe okhazikika zimadutsa mwakachetechete. Izi zikutanthauza kuti matimu omwe akuthamanga mopanda malire atha kudziunjikira zotengera zambiri zotayidwa bwino zomwe zimakhala ngati zikwapu kuchokera pamakina amtunduwo, kulepheretsa cholinga chake.

Khalidwe limodzi losawoneka bwino: mitundu ya mypy isanakwane 0.990 nthawi zina imawonetsa mndandanda[Osadziwika] mkati ndikukulitsa mndandanda[Aliyense] pa ntchito. Pambuyo pa-0.990, malingalirowo adalimbikitsidwa, koma kusinthaku kunaphwanya chiwerengero chodabwitsa cha ma codebases enieni omwe akhala akudalira khalidwe lolekerera popanda kuzindikira. Uwu ndi mutu womwe umabwerezedwa - kusintha kwa zomwe zili mu chidebe zopanda kanthu ndi zina mwa zosintha zosokoneza kwambiri chifukwa mawonekedwe ake amapezeka paliponse.

Pyright: Strict Inference and the "Unknown" Type

Pyright, yopangidwa ndi Microsoft ndi Powering Pylance mu VS Code, imakhala ndi malingaliro osiyana kwambiri. M'malo mobwerera mwakachetechete ku Chilichonse, pyright imasiyanitsa Yosadziwika (mtundu womwe sunadziwikebe) ndi Chilichonse (chosankha chotuluka pofufuza). Mukalemba x = [] mumayendedwe okhwima a pyright, zimatengera mndandanda[Zosadziwika] ndikunena za matenda, ndikukukakamizani kuti mupereke ndemanga.

Pyright alinso wamakani kwambiri pa kuchepetsa mkati mwa gawo. Ngati mulemba:

• x = [] yotsatiridwa ndix.append("hello") — pyright infers mndandanda[str]
• x = [] akutsatiridwa ndix.append(1) ndiyex.append("hello") — pyright infersmndandanda[int | str]
• x = [] adadutsa mwachindunji ku ntchito yomwe ikuyembekezera mndandanda[int] — pyright infers mndandanda[int] kuchokera pa tsamba loyimbira foni
• x = [] wabwerera kuchokera ku ntchito yopanda tanthauzo la mtundu wobwereza — pyright ikunena cholakwika m'malo mongopeka

Kufotokozera kwapawiri uku (pogwiritsa ntchito zonse zotsatila ndi mitundu yoyembekezeredwa kuchokera patsamba loyimbira foni) kumapangitsa pyright kukhala yolondola kwambiri kuposa mypy ya zotengera zopanda kanthu. The tradeoff is verbosity: pyright's hard mode mbendera pafupifupi 30-40% nkhani zambiri pa codebase yosadziwika bwino poyerekeza ndi machitidwe okhwima a mypy, malinga ndi kusanthula kwa malipoti angapo otsegula otsegula. Kwa magulu omwe amamanga machitidwe ovuta a backend - titi, nsanja yoyang'anira ma module 207 olumikizana omwe amatenga CRM, payroll, ndi analytics - kukhwima kwa pyright kumapeza zolakwika zobisika zomwe kungoganiza mopepuka kungaphonye.

Pytype ndi Pyre: Misewu Yochepa Yoyenda

Google's pytype imatenga mwina njira yabwino kwambiri. M'malo mofuna mafotokozedwe kapena kubwerera ku Chilichonse, pytype amagwiritsa kusanthula pulogalamu yonse kuti ayang'ane momwe chidebe chimagwiritsidwira ntchito kudutsa malire a ntchito. Ngati mupanga mndandanda wopanda kanthu mu ntchito imodzi ndikuipereka kwa ina yomwe imawonjezera manambala, pytype nthawi zambiri imatha kutanthauzira mndandanda[int]popanda zofotokozera zilizonse. Malingaliro ophatikizika awa ndi okwera mtengo kwambiri - pytype ndi yochedwa kwambiri kuposa mypy kapena pyright pama codebase akulu - koma imatulutsa zabwino zabodza zochepa pama code osazindikirika.

Pytype imayambitsanso lingaliro la "mitundu yochepa" ya zotengera zopanda kanthu. Chopangidwa chatsopano [] chimapeza mtundu wocheperako womwe umasinthidwa pang'onopang'ono pomwe chekicho chimagwiritsidwa ntchito kwambiri. Izi ndi zokongola koma zimatha kutulutsa mauthenga olakwika osokoneza pamene mtunduwo sungathe kuthetsedwa bwino, monga pamene chidebe chopanda kanthu chimadutsa muzinthu zingapo popanda kudzaza anthu.

Meta's pyre, pakadali pano, imayandikira kwambiri machitidwe a mypy koma osasintha kwambiri. Pyre amachitira x = [] monga mndandanda[osadziwika] ndipo amafuna kutanthauzira muzinthu zambiri. Kumene pyre imadzisiyanitsa ndi momwe imagwirira ntchito literals zopanda kanthu za mtanthauzira mawu omwe amagwiritsidwa ntchito ngati kwargs - njira yodziwika bwino pamawebusayiti. Pyre ali ndi malingaliro apadera oti afotokoze mitundu ya mtanthauzira mawu kuchokera pamikangano ya mawu osakira, kuchepetsa kulemedwa kwa mafotokozedwe mu ma codebases olemera. Poganizira kuti mapulogalamu amakono a pa intaneti amaphatikiza kugwiritsa ntchito kwambiri kumasula mtanthauzira mawu pokonza ndi kuyankha, pragmatism iyi imapereka phindu.

Zochitika Zenizeni Zapadziko Lonse: Pamene Inference Divergence Bites

Kusiyana pakati pa zoyesa mitundu zitha kuwoneka ngati zamaphunziro mpaka mutakumana nazo mu codebase yopanga. Ganizirani za njira zodziwika bwino zamabizinesi: kukhazikitsa dongosolo la data lomwe limakhala ndi anthu motsatira.

Zotengera zopanda kanthu zowopsa kwambiri sizomwe zimalemba mbendera - ndizomwe zimadutsa mwakachetechete ndi mtundu wa uliyonse, zomwe zimalola kuti deta yosagwirizana iwunjikane popanda chenjezo mpaka ntchito yakumunsi ikawonongeka panthawi yothamanga ndiTypeError zomwe sizingatheke kuti zibwerere ku chiyambi chake.

Chitsanzo chenicheni: gulu lomwe linayambitsa fintech linanena kuti likugwiritsa ntchito masiku atatu kuthetsa vuto la kupanga pomwe mndandanda wopanda kanthu, womwe unayambika pa ntchito yokonza malipiro, umatchedwa mndandanda[Any] ndi mypy. Mndandandawo umayenera kukhala ndi zinthu Decimal pa ndalama zandalama, koma njira ya ma code inali kuwonjezera ma fit m'malo mwake. Kulingalira mofatsa kwa Mypy kunalola mwakachetechete. Vutoli lidawonekera kokha pamene zolakwika zozungulira mu masamu oyandama zidapangitsa kusiyana kwa $ 0.01 pagulu la ma invoice 12,000. Akadagwiritsa ntchito pyright mosamalitsa, kapena kungofotokozera mndandanda wopanda kanthu ngati mndandanda[Decimal], cholakwikacho chikadagwidwa panthawi yachitukuko.

Ku Mewayz, komwe nsanja imakonza ma invoice, kuwerengetsa malipiro, ndi kuwerengera ndalama muakaunti ya ogwiritsa ntchito 138,000+, kusiyana kwamtundu wamtundu uwu sikungoyerekeza - ndi kusiyana pakati pa kulipira koyenera ndi kuwerengeranso kokwera mtengo. Kuwongolera mosamalitsa kulemba mozama poyambitsa zotengera ndi imodzi mwazinthu "zotopetsa" zomwe zimalepheretsa zochitika zosangalatsa zopanga.

Njira Zabwino Kwambiri Poyambitsa Chikhombo Choteteza

Mosasamala kanthu kuti gulu lanu limagwiritsa ntchito chowunikira chamtundu wanji, pali njira zenizeni zothetsera kusatsimikizika kwachidebe chopanda kanthu. Cholinga chake ndikusadalira zotengera zopanda kanthu - fotokozerani mtunduwo momveka bwino kotero kuti nambala yanu ikhale yosunthika pamacheke onse komanso osatengera kusintha kwamakhalidwe pakati pamitundu.

1. Nthawi zonse fotokozerani zosintha zachidebe zopanda kanthu. Lembanizotsatira: list[int] = [] m'malo mwa zotsatira = []. Mtengo wocheperako wa verbosity ndi wocheperako poyerekeza ndi nthawi yokonzanso yosungidwa. Kuchita kumodzi kumeneku kumachotsa pafupifupi 80% ya nkhani zopanda kanthu za zotengera.
2. Gwiritsani ntchito ntchito za fakitale pazotengera zovuta. M'malo mwa cache = {}, lembani ntchito ngati def make_cache() -> dict[str, list[UserRecord]]: bwererani {}. Mafotokozedwe amtundu wobwerera amapangitsa kuti mtundu wake ukhale wosamveka komanso wodzilemba okha.
3. Kukonda zomanga zotayidwa kuposa zilembo zamitundu yosakhala yaing'ono. Lembani zinthu: set[int] = set() m'malo modalira malingaliro omveka. Kwadefaultdict ndiCounter, nthawi zonse perekani mtundu wa parameter: mawerengero: Counter[str] = Counter().
4. Sinthani mawonekedwe okhwima a cholozera chamtundu wanu kuti mupeze khodi yatsopano. Zonse za mypy ndi pyright zimathandizira pafayilo iliyonse kapena masinthidwe atsamba lililonse. Yambitsani kuyang'ana mosamalitsa ma module atsopano kwinaku mukusamuka pang'onopang'ono ma code olowa. Izi zimalepheretsa kudziunjikira kwa makontena atsopano olembedwa mosabisa.
5. Onjezani choyesa chofananira ndi payipi yanu ya CI. Kuthamanga mypy ndi pyright pa codebase yanu kumapeza kusiyana koyambirira. Ngati chitsanzo chikudutsa chofufuza chimodzi koma chikulephera china, ndi chizindikiro chakuti mtunduwo sunatchulidwe mokwanira.

Chithunzi Chachikulu: Lembani Kufufuza Monga Mayesero a Gulu

Zopanda kanthu za chidebe ndizovuta kwambiri pamtundu wa Python: kukangana pakati pa kumasuka ndi chitetezo. Lingaliro la Python la "tonse ndife akuluakulu ovomereza" limagwira ntchito bwino pakujambula ndi zolemba, koma makina opanga omwe amapereka ogwiritsa ntchito masauzande ambiri amafunikira zitsimikizo zamphamvu. Mfundo yakuti ma cheki akuluakulu anayi amatsutsana pa chinthu chofunika kwambiri monga mtundu wa [] imasonyeza kuti Python typing ecosystem ikukhwima.

Kwa magulu a uinjiniya omwe amamanga nsanja zovuta - kaya mukuwongolera ma microservices ochepa kapena makina ophatikizika okhala ndi mazana a ma module olumikizana ngati Mewayz's business OS - malangizo othandiza ndi osavuta: musadalire zotengera zopanda kanthu, sankhani chowunikira ndikuchikonza mosamalitsa, ndipo tsatirani zolemba ngati zolemba zomwe zitha kukhala zamakina. Mphindi zisanu zomwe zagwiritsidwa ntchito polemba mndandanda[invoice] m'malo mwa [] zidzakupulumutsirani maola ambiri osintha ma codebase anu akamakula.

Monga PEP 696 (zosankha zamtundu wanthawi zonse) ndi PEP 695 (mtundu wa parameter syntax) zikupitilira kukhazikika m'matembenuzidwe atsopano a Python, malembedwe a zilembo zachidule apitiliza kuwongolera. Kusiyana pakati pa "annotated" ndi "unnotated" Python idzachepa. Koma mpaka tsikulo, mitundu ya zotengera zowonekera ikhalabe imodzi mwazochita zapamwamba kwambiri za ROI mu zida za opanga Python - njira yaying'ono yomwe imapereka chiwongola dzanja pagawo lililonse, sprint iliyonse, ndi kutumiza kulikonse.

Mafunso Ofunsidwa Kawirikawiri

Nchifukwa chiyani olemba macheki sangathe kuvomereza mtundu wa mndandanda wopanda kanthu?

Mukalemba `x = []`, choyang'ana chamtundu chikuyenera kuwonetsa mtundu wopanda malingaliro omveka bwino. Oyang'anira osiyanasiyana amagwiritsa ntchito njira zosiyanasiyana: ena amatanthauzira `mndandanda[Aliyense]` (mndandanda wa chilichonse), pomwe ena amatha kuganiza zamtundu wina koma wolakwika ngati `mndandanda[Palibe]`. Kusowa kwa muyezo wapadziko lonse lapansi ndichifukwa chake amatsutsana. Kwa mapulojekiti omwe amagwiritsa ntchito ma checkers angapo, kusagwirizana uku kungakhale mutu waukulu, kuphwanya kusanthula mu chida chimodzi chomwe chimadutsa mu china.

Kodi njira yosavuta yokonzera zolakwika za m'chitengera zopanda kanthu ndi iti?

Yankho lolunjika kwambiri ndikupereka mawu omveka bwino. M'malo mwa `my_list = []`, lembani `my_list: list[str] = []` kuti mulengeze momveka bwino mtundu womwe mukufuna. Izi zimachotsa kusamveka konse kwa chowunikira chamtundu, kuwonetsetsa kuti magwiridwe antchito azida zosiyanasiyana monga mypy, Pyright, ndi Pyre. Mchitidwewu ndi wovomerezeka pazoyambira zonse zopanda kanthu kuti mupewe zolakwika.

Kodi ndimayendetsa bwanji zotengera zopanda kanthu mkati mwa matanthauzidwe amkalasi?

Iyi ndi nkhani yofala chifukwa zofotokozera m'makalasi zimafunikira kuthandizidwa mwapadera. Muyenera kugwiritsa ntchito `kuchokera __future__ zolowetsa zolowetsa` kapena mawu a `ClassVar` ngati mndandandawo ukuyenera kukhala wagulu. Mwachitsanzo, `class MyClass: my_list: ClassVar[mndandanda[str]] = []`. Popanda izi, choyang'anira mtundu chikhoza kuvutikira kutsimikizira mtunduwo, zomwe zimabweretsa zolakwika.

Kodi pali zida zothandizira kukonza zolemba pamapulojekiti akuluakulu?

Inde, ma cheki apamwamba ngati Pyright (omwe amathandizira Pylance mu VS Code) ndiabwino kwambiri pakuwongolera zovuta. Kwa ma codebase akulu, nsanja ngati Mewayz (yopereka ma module 207 owunikira $19/mwezi) atha kupereka kuwunika kozama, kosasinthasintha komanso kuthandizira kulimbikitsa machitidwe pagulu lanu lonse, kuchepetsa zosagwirizana zomwe zafotokozedwa m'nkhaniyi.