Callable ClassVar is incorrectly treated as a method

from typing import Callable, MutableMapping, ClassVar

class C:
    x: ClassVar[Callable[[], MutableMapping]] = dict
    def f(self) -> MutableMapping:
        return self.x()  

c = C()
print(c.f())

Gives

a.py:6: error: Attribute function "x" with type "Callable[[], MutableMapping[Any, Any]]" does not accept self argument

This is a known problem / feature. The same happens without ClassVar as well:

from typing import Callable, MutableMapping, ClassVar

class C:
    x: Callable[[], MutableMapping] = dict
    def f(self) -> MutableMapping:
        # error: Attribute function "x" with type "Callable[[], MutableMapping[Any, Any]]" does not accept self argument
        return self.x()

c = C()
print(c.f())

Related #9489

FWIW #9489 was fixed by #10548. But this appears to still be an issue

Closing as a duplicate of #6910 (which is not about ClassVars, but is the same but nonetheless)

Can we re-open this? It's not fixed and not a duplicate of #6910. The related issue for instance vars was fixed, but it remains a problem for ClassVar[Callable[...]].

Blast from the past!

FWIW there's a recent ongoing Discourse discussion about this

https://discuss.python.org/t/when-should-we-assume-callable-types-are-method-descriptors/92938

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Callable ClassVar is incorrectly treated as a method #11077

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Callable ClassVar is incorrectly treated as a method #11077

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sobolevn commented on Sep 17, 2021

thejcannon commented on Jan 31, 2022

AlexWaygood commented on Mar 26, 2022

h4l commented on Jun 15, 2025

thejcannon commented on Jun 15, 2025

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