alru_cache decorator on a class method causes mypy error: Missing positional argument "self"

[atusy]

Thank you for the amazing project.

I'm trying to apply alru_cache on a class method, but mypy raises an error and a note:

error: Missing positional argument "self" in call to "f" of "X"  [call-arg]
note: "__call__" is considered instance variable, to make it class variable use ClassVar[...]

below is the reproducible example tested with mypy 1.1.1 and asyncstdlib 3.10.5

from asyncstdlib.functools import lru_cache as alru_cache

class X:
    @alru_cache()
    async def f(self) -> int:
        return 1

    async def g(self) -> int:
        return await self.f()

[maxfischer2781]

This might take a bit. The standard library type hints just ignore all arguments, making the implicit-self case trivially covered. I need to check if it is possible to cover the self case explicitly or disable argument checking only for methods.

[maxfischer2781]

It looks like it is not possible to stitch things together using ParamSpec: python/mypy#13222

[maxfischer2781]

Turns out in principle it is possible to annotate a descriptor (__get__ method) to have ParamSpec stitch together instance/class and other parameters. However, it doesn't seem possible to break up a captured "async callable" TypeVar this way. So it is not clear how the function and method annotations can co-exist cleanly.

For the time being, #105 will implement a middle ground: Full type support on functions, parameter erasure on methods.

[atusy]

Wow! Thank you for your hard work.

[maxfischer2781]

Looks like I found out how to stitch together self and other parameters. Method parameters should fully work with #129.

[atusy]

How nice!!