(🐞) __future__._Feature.getMandatoryRelease should be Optional

[KotlinIsland]

And it shouldn't be a sys._version_info, it should be a 5-tuple.

This is a 5-tuple, of the same form as sys.version_info, or, if the feature was dropped, or it's release date is undetermined, is None.

This is also needed for python/cpython#93628

[graingert]

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]

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]

mypy doesn't narrow the tuple here.

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

[AlexWaygood]

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

[KotlinIsland]

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

[KotlinIsland]

or not...

[AlexWaygood]

_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]

python/typing#956

[graingert]

Could you do something like:

class _Feature:
    ...

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

[AlexWaygood]

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.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[KotlinIsland]

Now have to make sure mypy works with it...

[KotlinIsland]

Mypy should be fine, it doesn't look at the values.