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Attribute functions in stubs and dataclasses.Field #10750
Description
So something like the following gives me main.py:4: error: Attribute function "default_factory" with type "Callable[[], _T]" does not accept self argument:
import dataclasses
def foo(x: dataclasses.Field):
if x.default_factory is not dataclasses.MISSING:
...
Okay, hmm. Let's try to repro:
from typing import Callable
class X:
# f: Callable[[], str]
def __init__(self) -> None:
self.f = lambda: "whatever"
x = X()
reveal_type(x.f)
reveal_type(x.f())
This works fine! But if you uncomment the commented line, then you're back to the error, which is problematic if you want to express this in stubs. I can get things checking again by using a callback protocol — is that the best one can do?
Activity
hauntsaninja commentedon Jul 1, 2021
Opened python/typeshed#5718 to help with this
hauntsaninja commentedon Jul 1, 2021
Okay, also found #6910
AlexWaygood commentedon Mar 26, 2022
@hauntsaninja, are you happy for this to be closed, given the immediate problem has been resolved, and given that it's the same bug as #6910? :)