Python Type Checker Ntotoho: Nneɛma a Ɛda Hɔ Nsusuwii

Nea Enti a Nsukorabea Da mpan Bu Python Type Checkers — Ne Nea Wubetumi Ayɛ Afa Ho

Python nkakrankakra typing nhyehyɛe no anyin kɛse fi bere a PEP 484 de type hints bae wɔ afe 2015. Ɛnnɛ, developers ɔpepem pii de wɔn ho to static type checkers so sɛ wɔbɛkyere bɔne ansa na wɔabɔ production. Nanso type system no ntwea bi a ɛyɛ anifere na ɛyɛ abasamtu wɔ hɔ a ɛda so ara ma mfiridwumayɛfo a wɔn ho akokwaw mpo hintiw: type bɛn na ade a hwee nni mu wɔ? Sɛ wo kyerɛw x = [] a enni nkyerɛkyerɛmu a, ɛsɛ sɛ wo type checker no susuw — na checker ahorow guess wɔ ɔkwan soronko so. Saa mpaepaemu yi de ɔhaw ankasa ba akuw a wɔhwɛ codebases akɛse so, baabi a sɛ wɔsesa anaa wɔka type checkers bom a, ebetumi ama mfomso ɔhaha pii a wɔnhwɛ kwan aba anadwo biako.

Saa asɛm yi mu paapae sɛnea Python type checkers atitiriw anan — mypy, pyright, pytype, ne pyre — di empty container inference ho dwuma, nea enti a wɔn adwene nhyia, ne akwan a mfaso wɔ so a wubetumi afa so akyerɛw type-safe Python a wo nnwinnade a wopaw mfa ho.

Ɔhaw Titiriw: Nsukorabea a Da mpan no Fi Awosu Mu Nhumu

Susuw Python line a ɛnyɛ bɔne yi ho: results = []. So nea efi mu ba yɛ list[int]? kyerɛwtohɔ[str] bi? list[dict[str, Biara]] bi? Sɛ nsɛm foforo a ɛfa ho nni hɔ a, nokwarem no, ɔkwan biara nni hɔ a wobɛfa so ahu. Python runtime no mfa ho — lists yɛ heterogeneous wɔ abɔdeɛ mu — nanso static type checkers hia sɛ wɔde concrete type bi ma variable biara na wɔayɛ wɔn adwuma. Wei de nhyɛsoɔ titire ba Python dynamic flexibility ne guarantees a static analysis bɔ mmɔden sɛ ɛde bɛma ntam.

Ɔhaw no ne nsɛm asekyerɛ nhoma ne nhyehyɛe ahorow bom. Wɔkyekyɛ {} a hwee nni mu no mu ankasa sɛ dict, ɛnyɛ set, a ɛde kasamufa mu adwenem naayɛ ka type-level ambiguity no atifi. Na nested containers — susuw defaultdict(list) anaa results = {k: [] ma k wɔ keys mu} — pia inference engine ahorow kɔ wɔn anohyeto so. Type checker biara ayɛ n’ankasa heuristics, na nsonsonoe no yɛ kɛse sen sɛnea developers dodow no ara hu.

Wɔ nnwumayɛ nhyehyɛeɛ a ɛdi adwuma ankasa ho dwuma — sɛ ɛyɛ CRM a ɛdi adetɔfoɔ kyerɛwtohɔ ho dwuma, invoicing module a ɛma line items, anaa analytics pipeline a ɛboaboa metrics ano — nsuo a hwee nni mu pue daa sɛ mfitiaseɛ nhwɛsoɔ. Wɔn types a wobenya wɔ ɔkwan a ɛnteɛ so no nyɛ linter kɔkɔbɔ ahorow kɛkɛ; ebetumi akata mfomso ankasa a ɛtwetwe kɔ runtime mu.

Mypy: Nsusuwii a Wɔatu Akɔ akyiri a Ɛnkyerɛ Biara

Mypy, Python type checker a akyɛ sen biara na wɔagye atom kɛse no, fa ɔkwan a ɛyɛ mmerɛw kakra so wɔ nsukorade a hwee nni mu ho. Sɛ ɛhyia x = [] wɔ function scope a, ɛbɔ mmɔden sɛ defer type gyinaesi na ɛkyerɛ element type no fi dwumadie a ɛdi akyire no mu. Sɛ wokyerɛw x = [] a x.append(42) di akyi a, mypy bɛkyerɛ sɛ list[int]. Saa "join" nhyehyeɛ yi yɛ adwuma yie ma ɛyɛ nwonwa ma nsɛm a ɛyɛ tẽẽ a wɔde ahina no ahyɛ mu ma wɔ beaeɛ korɔ no ara mu.

Nanso, mypy suban sesa kɛse a egyina nsɛm a ɛfa ho ne kateeyɛ nhyehyɛe so. Wɔ module scope (top-level code), anaa sɛ wɔde container no kɔ function foforo mu ansa na wɔahyɛ no ma a, mypy taa san kɔ list[Any]. Wɔ --strict frankaa ase no, eyi kanyan mfomso, nanso wɔ default mode mu no ɛtwam komm. Wei kyerɛ sɛ akuo a wɔde mypy tu mmirika a enni strict mode no tumi boaboa nsuo a wɔakyerɛw no implicitly du du pii ano a ɛyɛ adwuma sɛ guankɔbea hatches fi type system no mu, di n’atirimpɔw so nkonim.

Su biako a ɛyɛ anifere titiriw: mypy nkyerɛase ahorow a edi 0.990 anim no ɛtɔ mmere bi a ɛbɛkyerɛ sɛ list[Unknown] wɔ mu na afei ɛtrɛw kɔ list[Any] wɔ dwumadi mu. Wɔ 0.990 akyi no, wɔkyekyeree nsusuwii no mu den, nanso nsakrae no bubuu wiase ankasa mu codebases dodow bi a ɛyɛ nwonwa a na wɔde wɔn ho ato suban a wɔma ho kwan no so a na wonnim. Eyi yɛ asɛmti a ɛsan ba bio — nsakrae a ɛba ade hunu mu nsusuwii mu no ka type checker updates a ɛhaw adwene kɛse no ho efisɛ nhwɛso ahorow no wɔ baabiara.

Pyright: Nsusuwii a Ɛyɛ Katee ne "Wɔnnim" Type

Pyright, a Microsoft na ɛyɛeɛ na ɛma Pylance tumi wɔ VS Code mu no, fa nyansapɛ gyinabea soronko koraa. Sɛ anka ɛbɛyɛ komm asan akɔ Any so no, pyright kyerɛ nsonsonoeɛ a ɛda Unknown (type a wonnya nsii ho gyinaeɛ) ne Any (type checking a ɛda adi pefee a wɔayi afiri mu) ntam. Sɛ wo kyerɛw x = [] wɔ pyright strict mode mu a, ɛkyerɛ list[Unknown] na ɛbɔ diagnostic bi ho amanneɛ, na ɛhyɛ wo sɛ fa nkyerɛkyerɛmu bi ma.

Pyright nso yɛ basabasa kɛse wɔ ntwitwagye wɔ scope mu. Sɛ wokyerɛw a:

• x = [] a x.append("hello") di akyi — pyright kyerɛ sɛ list[str]
• x = [] akyi no x.append(1) afei x.append("hello") — pyright kyerɛ sɛ list[int | str]
, ɛyɛ nea ɛwɔ hɔ
• x = [] wɔde kɔ adwuma bi a ɛhwɛ kwan sɛ list[int] — pyright kyerɛ list[int] fi frɛ-beae nsɛm a ɛfa ho
mu
• x = [] asan afi dwumadie bi a enni sanba type nkyerɛkyerɛmu — pyright bɔ mfomsoɔ ho amanneɛ sene sɛ ɛbɛsusu

Saa akwan abien nsusuwii yi (a wɔde di dwuma akyiri yi ne ahorow a wɔhwɛ kwan fi frɛ sait ahorow mu nyinaa di dwuma) ma pyright yɛ nea ɛda nsow pɛpɛɛpɛ sen mypy ma nsukorade a hwee nni mu. Aguadi no yɛ verbosity: pyright strict mode frankaa bɛyɛ 30-40% nsɛm pii wɔ typical unannotated codebase sɛ wɔde toto mypy strict mode ho a, sɛnea nhwehwɛmu a efi open-source migration amanneɛbɔ pii mu kyerɛ no. Wɔ akuw a wɔkyekye backend nhyehyɛe a ɛyɛ den — ka sɛ, platform a ɛhwɛ module ahorow 207 a ɛka bom a ɛfa CRM, akatua, ne nhwehwɛmu ho — pyright kateeyɛ no kyere interface mismatches a ɛyɛ anifere a lenient inference bɛyera.

Pytype ne Pyre: Akwan a Wɔntuo pii

Google pytype no fa ebia ɔkwan a ɛyɛ adwuma sen biara. Sɛ anka ɛbɛhia nkyerɛkyerɛmu anaasɛ ɛbɛsan akɔ Any so no, pytype de whole-program analysis di dwuma de di sɛnea wɔde adekorabea bi di dwuma wɔ dwumadie hyeɛ so no akyi. Sɛ wobɔ list a hwee nni mu wɔ dwumadie baako mu na wode kɔ foforɔ a ɛde integers ka ho a, pytype taa tumi susu list[int] a nkyerɛkyerɛmu biara nni mu koraa. Saa cross-function inference yi bo yɛ den wɔ akontabuo mu — pytype yɛ brɛoo kɛseɛ sene mypy anaa pyright wɔ codebases akɛseɛ so — nanso ɛma atoro positives kakraa bi ba code a wɔannotated so.

Pytype nso de adwene a ɛne "afã ahorow" ma nkuku a hwee nni mu no ba. [] a wɔayɛ no foforɔ no nya type fã bi a wɔayɛ no foforɔ nkakrankakra berɛ a checker no hyia dwumadie pii. Eyi yɛ adwene mu fɛfɛɛfɛ nanso ebetumi ama mfomso nkrasɛm a ɛyɛ basaa aba bere a wɔrentumi nsiesie ɔfã bi su no koraa, te sɛ bere a ade a hwee nni mu sen fa dwumadi ahorow pii mu a wɔanhyɛ mu ma da.

Meta pyre, saa bere yi, hews bɛn mypy suban nanso ɛwɔ defaults a ɛyɛ den. Pyre di x = [] sɛ list[unknown] na ɛhwehwɛ sɛ wɔkyerɛw nsɛm wɔ nsɛm dodow no ara mu. Baabi a pyre da nsow ne sɛnea ɔdi nsɛm asekyerɛ nhoma mu nsɛmfua a hwee nni mu a wɔde di dwuma sɛ kwargs — nhwɛso a ɛtaa ba wɔ wɛb nhyehyɛe mu. Pyre wɔ special-case logic a ɔde bɛkyerɛ nsɛm asekyerɛ nhoma ahorow afi keyword argument contexts mu, a ɛtew annotation adesoa so wɔ framework-heavy codebases mu. Sɛ yɛhwɛ sɛ nnɛyi wɛb aplikeshɔn dodow no ara fa nsɛm asekyerɛ nhoma a wɔde yi nneɛma mu a wɔde di dwuma kɛse ma nhyehyɛe ne abisade ho dwumadie ho a, saa pragmatism yi tua mfasoɔ.

Wiase Ankasa Nkɛntɛnso: Bere a Inference Divergence Ka

Nsonsonoe a ɛda type checkers ntam no betumi ayɛ te sɛ nea ɛyɛ adesua kosi sɛ wubenya bi wɔ production codebase mu. Susuw nhwɛsoɔ a ɛtaa ba wɔ adwumayɛ dwumadie mu: data nhyehyɛɛ a ɛhyɛ aseɛ a ɛyɛ nea wɔahyɛ no ma wɔ tebea mu.

a wɔde ahyɛ mu

Akoraeɛ a hwee nni mu a ɛyɛ hu paa no nyɛ deɛ type checkers frankaa — ɛyɛ deɛ ɛde Any type a wɔasusu sɛ ɛtwam komm, ma kwan ma data a ɛnhyia boaboa ano a wɔmmɔ kɔkɔ kɔsi sɛ downstream function bi bɛbɔ wɔ runtime mu a TypeError a ɛkame ayɛ sɛ ɛrentumi nyɛ yie sɛ wobɛsan akɔ ne mfitiaseɛ.

na ɛkyerɛ sɛ woayɛ

Nhwɛsoɔ pɔtee: kuw bi a wɔwɔ fintech mfitiaseɛ bi bɔɔ amanneɛ sɛ wɔde nnansa de siesiee adwumayɛ ho asɛm bi wɔ baabi a wɔde mypy susuwii sɛ list a hwee nni mu, a wɔhyɛɛ aseɛ wɔ akatua dwumadie dwumadie mu sɛ list[Any]. Na ɛsɛ sɛ list no kura Decimal nneɛma ma sika dodoɔ, nanso na koodu kwan bi de float botaeɛ reka ho mmom. Mypy nsusuwii a ɛyɛ brɛoo no maa kwan komm. Mfomso no puei bere a mfomso a ɛwɔ rounding mu wɔ float akontaabu mu maa $0.01 a ɛne ne ho nhyia wɔ batch a ɛyɛ 12,000 invoices so nkutoo. Sɛ wɔde pyright dii dwuma wɔ strict mode mu, anaasɛ wɔkyerɛw nsɛm a ɛda mpan no mu kɛkɛ sɛ list[Decimal] a, anka wɔbɛkyere bɔne no wɔ nkɔso bere mu.

Wɔ Mewayz, faako a platform no di invoicing, akatua akontaabu, ne sikasɛm mu nhwehwɛmu ho dwuma wɔ 138,000+ user accounts so no, saa type-safety gap yi nyɛ theoretical — ɛyɛ nsonsonoe a ɛda payroll runs a ɛteɛ ne recalculations a ɛho ka yɛ den ntam. Nteɛsoɔ a ɛyɛ katee a wɔde kyerɛw nsɛm a ɛfa container initialization ho yɛ saa "boring" engineering practices a ɛsiw production incidents a ɛyɛ anigyeɛ ano.

Nneyɛe Pa a Ɛfa Defensive Container Initialization ho

Ɛmfa ho type checker a wo kuw no de di dwuma no, akwan pɔtee bi wɔ hɔ a wobɛfa so ayi ade a hwee nni mu a emu nna hɔ no afi hɔ koraa. Botaeɛ ne sɛ woremfa wo ho nto inference so da mma containers a hwee nni mu — ma type no nna adi pefee sɛdeɛ ɛbɛyɛ a wo code no bɛtumi afa checkers nyinaa so na ayɛ immune to inference suban nsakraeɛ wɔ versions ntam.

1. Bere nyinaa kyerɛw adekorabea nsakrae a hwee nni mu. Kyerɛw aba: list[int] = [] sen sɛ wobɛkyerɛw aba = []. Verbosity ka ketewa no yɛ nea wontumi mmu ani ngu so sɛ wɔde toto debugging bere a wɔakora so no ho a. Saa adeyɛ biako yi yi bɛyɛ 80% fi nsukorade a hwee nni mu nsusuwii ho nsɛm.
2. Fa adwumayɛbea dwumadie di dwuma ma nsukoradeɛ a ɛyɛ den. Sɛ anka wode cache = {} bedi dwuma no, kyerɛw dwumadie te sɛ def make_cache() -> dict[str, list[UserRecord]]: san kɔ {}. Sankɔhwɛ type nkyerɛkyerɛmu no ma type a wɔahyɛ da ayɛ no yɛ nea emu nna hɔ na ɛyɛ ne ho kyerɛwtohɔ.
3. Pɛ typed constructors sen literals ma types a ɛnyɛ trivial. Twerɛ items: set[int] = set() sen sɛ wode wo ho bɛto set comprehension inference so. Wɔ defaultdict ne Counter ho no, fa type parameter no ma bere nyinaa: counts: Counter[str] = Counter().
4. Hyɛ wo type checker no strict mode no ma code foforo. Mypy ne pyright nyinaa boa fael biara anaa directory biara nhyehyɛe. Ma nhwehwɛmu a emu yɛ den nyɛ adwuma wɔ module foforo so bere a wode nkakrankakra retu agyapade koodu no. Wei siw nsukorade foforo a wɔakyerɛw no pefee a ɛbɛboaboa ano no ano.
5. Fa type checker ntotoho ka wo CI pipeline ho. Sɛ wode mypy ne pyright nyinaa tu mmirika wɔ wo codebase so a, ɛkyere inference divergence ntɛm. Sɛ nhwɛsoɔ bi twa checker baako nanso ɛdi nkoguo wɔ foforɔ so a, ɛyɛ sɛnkyerɛnne a ɛkyerɛ sɛ type no ntumi nkyerɛ pefee sɛdeɛ ɛsɛ.

Mfonini Kɛse: Type Checking sɛ Kuw Adeyɛ

Empty container inference yɛ awiei koraa no microcosm a ɛyɛ asɛnnennen kɛse wɔ Python type nhyehyɛe mu: nhyɛso a ɛda ahotɔ ne ahobammɔ ntam. Python nyansapɛ a ɛne sɛ "yɛn nyinaa yɛ mpanyimfo a yɛpene so" yɛ adwuma fɛfɛɛfɛ ma prototyping ne scripts, nanso production systems a ɛsom nnipa mpempem pii a wɔde di dwuma no hia guarantees a emu yɛ den. Nokwasɛm a ɛyɛ sɛ type checkers atitiriw baanan adwene nhyia wɔ biribi a ɛyɛ mfitiasede te sɛ [] type no ho no si so dua sɛ Python typing ecosystem no da so ara nyin.

| mfiri a wɔde di ho adanse. Simma anum a wode kyerɛw list[Invoice] sen sɛ wobɛkyerɛw [] no bɛma woakora nnɔnhwerew pii a wode bɛsiesie mfomso bere a wo codebase no reyɛ kɛse.

Bere a PEP 696 (default type parameters) ne PEP 695 (type parameter syntax) kɔ so si fam wɔ Python nkyerɛase foforo mu no, ergonomics a ɛfa typing a ɛda adi pefee ho no bɛkɔ so atu mpɔn. Ɔkwan a ɛda "annotated" ne "unannotated" Python ntam no bɛtew. Nanso ɛde besi saa da no, container ahorow a ɛda adi pefee da so ara yɛ nneyɛe a ɛkorɔn sen biara a ɛwɔ ROI wɔ Python developer no adwinnade mu no mu biako — nteɛso ketewa bi a etua mfɛntom a wɔaka abom wɔ module biara, sprint biara, ne production deployment biara mu.

Nsɛmmisa a Wɔtaa Bisa

Dɛn nti na type checkers ntumi nnye ntom wɔ list a ɛda mpan no su ho?

Sɛ wokyerɛw `x = []` a, ɛsɛ sɛ type checker no kyerɛ type bi a enni hints a ɛda adi pefee. Checkers ahodoɔ de akwan ahodoɔ di dwuma: ebinom fa `list[Any]` (biribiara din), berɛ a ebinom nso bɛtumi asusu sɛ ɛyɛ type pɔtee nanso ɛntene te sɛ `list[None]`. Amansan gyinapɛn a wonni yi nti na wɔn adwene nhyia no. Wɔ nnwuma a wɔde checkers pii di dwuma no, saa a enhyia yi betumi ayɛ tiyɛ kɛse, abubu nhwehwɛmu wɔ adwinnade biako mu a ɛtwam wɔ foforo mu.

Ɔkwan bɛn na ɛyɛ mmerɛw a wobɛfa so asiesie mfomsoɔ a ɛwɔ ahina a hwee nni mu?

Ano aduru a ɛyɛ tẽẽ sen biara ne sɛ wode type annotation a ɛda adi pefee bɛma. Sɛ anka wobɛkyerɛw `my_list = []` no, kyerɛw `my_list: list[str] = []` na fa ɔkwan a wopɛ sɛ wofa so no to gua pefee. Wei yi adwenem naayɛ nyinaa fi hɔ ma type checker no, hwɛ hu sɛ nneyɛe a ɛkɔ so daa wɔ nnwinnade ahorow te sɛ mypy, Pyright, ne Pyre so. Wɔkamfo saa adeyɛ yi kyerɛ ma container initializations a ɛda mpan nyinaa sɛnea ɛbɛyɛ a wobesiw inference mfomso ano.

Mɛyɛ dɛn adi nkukuo a hwee nni mu ho dwuma wɔ adesua nkyerɛaseɛ mu?

Eyi yɛ asɛm a ɛtaa ba efisɛ nkyerɛkyerɛmu a ɛwɔ adesua ahorow mu hwehwɛ sɛ wodi ho dwuma titiriw. Ɛsɛ sɛ wode `from __future__ import annotations` import anaa `ClassVar` nkyerɛkyerɛmu di dwuma sɛ wɔahyɛ da ayɛ list no sɛ ɛbɛyɛ class su a. Sɛ nhwɛso no, `klas MeKlas: me_list: ClassVar [list [str]] = []`. Sɛ eyi nni hɔ a, ebia type checker no bɛpere sɛ ɔbɛkyerɛ type no yiye, na ɛde mfomso aba.

So nnwinnade bi wɔ hɔ a ɛbɛboa ma wɔadi saa nsɛm a wɔde kyerɛw nsɛm yi ho dwuma wɔ nnwuma akɛse mu?

Yiw, advanced type checkers te sɛ Pyright (a ɛma Pylance tumi wɔ VS Code mu) ye titiriw wɔ complex inference a wodi ho dwuma mu. Wɔ codebases akɛseɛ ho no, platforms te sɛ Mewayz (a ɛde nhwehwɛmu module 207 ma $19/ɔsram) betumi ama type checking a emu dɔ, a ɛkɔ so daa na aboa ma wɔahyɛ nkyerɛkyerɛmu nneyɛe wɔ wo kuw no nyinaa mu, abrɛ nsɛm a ɛnhyia a wɔaka ho asɛm wɔ asɛm no mu no ase.