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Different results in Python 3.12.1 vs Python 3.12.2 #335
Description
Small reproducer:
from dataclasses import dataclass
from typing_extensions import Protocol, runtime_checkable
@runtime_checkable # removing this decorator fixes the bug.
class HasConfig(Protocol):
pass
@runtime_checkable
class Action(HasConfig, Protocol):
pass
@dataclass
class Delete:
pass
delete = Delete()
print(isinstance(delete, Action))This prints False in 3.12.2, True in 3.12.1. Changing the import to from typing import Protocol, runtime_checkable also makes this bug disappear.
Activity
AlexWaygood commentedon Feb 15, 2024
This is because Python 3.12.2 changed the implementation of
@runtime_checkableso that it now adds an attribute to the class it decorates, and the latest release oftyping_extensionsjust re-exports thetypingmodule's version of the@runtime_checkablerather than defining its own version.We've actually already fixed this bug on the
typing_extensionsmain branch (in 004b893), but the fix hasn't been released yet.@JelleZijlstra -- thoughts on possibly reconsidering #324 (comment)? I think it might be worth cutting a patch release for this :/ Sorry for the bother :(
JelleZijlstra commentedon Feb 16, 2024
I feel the changes are too big for a bugfix release. I merged the PEP 742 implementation and hopefully we can also get PEP 728 implemented in the next few days, then make a release on Sunday (#337).
AlexWaygood commentedon Feb 25, 2024
typing_extensions 4.10.0 has now been released, which should hopefully fix the issue! Let us know if you're still having problems @tfeldmann