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(🐞) __future__._Feature.getMandatoryRelease should be Optional #8232

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Merged
AlexWaygood merged 2 commits into from
Jul 3, 2022
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(🐞) __future__._Feature.getMandatoryRelease should be Optional #8232

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__future__._Feature.getMandatoryRelease should be Optional
KotlinIsland Jul 3, 2022
a403292
Use CamelCase for type alias
AlexWaygood Jul 3, 2022
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9 changes: 6 additions & 3 deletions stdlib/__future__.pyi
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Original file line number Diff line number Diff line change
@@ -1,9 +1,12 @@
import sys
from typing_extensions import TypeAlias

_VersionInfo: TypeAlias = tuple[int, int, int, str, int]

class _Feature:

@graingert graingert Jul 3, 2022

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Might be cool to have this as a

_T_minver = TypeVar("_T_minver", bound=tuple[int, int, int, str, int])
_T_maxver = TypeVar("_T_maxver", bound=tuple[int, int, int, str, int] | None)

class _Feature(Generic[_T_minver, _T_maxver]):
    ...

So that the runtime constants can be exposed at type checking time

@AlexWaygood AlexWaygood Jul 3, 2022

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I don't think that's necessary here tbh, and making classes generic in the stub when they're not at runtime can have some unfortunate consequences.

@KotlinIsland KotlinIsland Jul 3, 2022

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mypy doesn't narrow the tuple here.

https://mypy-play.net/?mypy=latest&python=3.10&gist=40fa9e86e067c31b64565ef816390e0a

@AlexWaygood AlexWaygood Jul 3, 2022

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Although it does narrow the type here: https://mypy-play.net/?mypy=latest&python=3.10&gist=d7701f4a0f78a3c0e2a2e514ca12d269

@KotlinIsland KotlinIsland Jul 3, 2022

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@AlexWaygood it doesn't narrow to the the literal values

@KotlinIsland KotlinIsland Jul 3, 2022

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or not...

@AlexWaygood AlexWaygood Jul 3, 2022

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_Feature is private so it's not exposed right?

It is documented, though. And I still think in general we shouldn't make things generic in the stub when they're not at runtime unless there's a compelling use case for it, which I don't really see here.

@KotlinIsland KotlinIsland Jul 3, 2022

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python/typing#956

@graingert graingert Jul 3, 2022

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Could you do something like:

class _Feature:
    ...

class _StubOnlyFeature(_Feature, Generic[...]):
    ...

@AlexWaygood AlexWaygood Jul 3, 2022

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Could you do something like:

class _Feature:
    ...

class _StubOnlyFeature(_Feature, Generic[...]):
    ...

I'm even less a fan of that ;)

I prefer making classes generic in the stub to introducing lies about what class certain objects are at runtime.

def __init__(self, optionalRelease: sys._version_info, mandatoryRelease: sys._version_info, compiler_flag: int) -> None: ...
def getOptionalRelease(self) -> sys._version_info: ...
def getMandatoryRelease(self) -> sys._version_info: ...
def __init__(self, optionalRelease: _VersionInfo, mandatoryRelease: _VersionInfo | None, compiler_flag: int) -> None: ...
def getOptionalRelease(self) -> _VersionInfo: ...
def getMandatoryRelease(self) -> _VersionInfo | None: ...
compiler_flag: int

absolute_import: _Feature
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