ABCMeta issue #506

Moosems · 2025-03-04T17:39:02Z

Moosems
Mar 4, 2025

Hey @leycec its me again, here to steal your week once more 🙂

I am trying to do some funky class stuff in a project but am getting a beartype issue on the latest version. Heres a very simplified example of what I'm doing:

from abc import ABC

class Foo(ABC):
    ...
    
class Bar(Foo):
    ...
    
x: Foo = Bar()

Foo is a skeleton class meant to force good API usage and Bar is a subclass doing said API usage. When I run this in my actual project with the actual classes I get this:

__________________________________________________________ test_extension_manager ___________________________________________________________

    def test_extension_manager():
        # Test manager creation
        data = "Arbitrary data type"
>       manager = ExtensionManager("tests/test_extensions", data)

tests/test_manager.py:10:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
<@beartype(estensione.manager.ExtensionManager.__init__) at 0x110391440>:36: in __init__
    ???
estensione/manager.py:69: in __init__
    self.reload_all()
<@beartype(estensione.manager.ExtensionManager.reload_all) at 0x110392160>:12: in reload_all
    ???
estensione/manager.py:306: in reload_all
    info, extension = self.preload_extension(item)
<@beartype(estensione.manager.ExtensionManager.preload_extension) at 0x110391ee0>:33: in preload_extension
    ???
estensione/manager.py:154: in preload_extension
    extension: BaseExtension | None = getattr(module, "Extension", None)
venv/lib/python3.12/site-packages/beartype/door/_func/doorcheck.py:137: in die_if_unbearable
    func_raiser(obj)  # pyright: ignore
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

__beartype_pith_0 = <class 'test_ext_4.Extension'>
__beartype_object_4565839424 = (<class 'estensione.extension.BaseExtension'>, <class 'NoneType'>)
__beartype_exception_prefix = 'Callable \x1b[1m\x1b[35mestensione.manager.ExtensionManager.preload_extension()\x1b[0m local variable "\x1b[1m\x1b[35mextension\x1b[0m" '
__beartype_get_violation = <function get_hint_object_violation at 0x11030dd00>, __beartype_hint = estensione.extension.BaseExtension | None
__beartype_conf = BeartypeConf(warning_cls_on_decorator_exception=<class 'beartype.roar._roarwarn.BeartypeClawDecorWarning'>)

>   ???
E   beartype.roar.BeartypeDoorHintViolation: Callable estensione.manager.ExtensionManager.preload_extension() local variable "extension" value <class 'test_ext_4.Extension'> violates type hint estensione.extension.BaseExtension | None, as <class "abc.ABCMeta"> <class 'test_ext_4.Extension'> not <class "estensione.extension.BaseExtension"> or <class "builtins.NoneType">.

<@beartype(__beartype_checker_6) at 0x7fcac3570950>:23: BeartypeDoorHintViolation
========================================================== short test summary info ==========================================================
FAILED tests/test_manager.py::test_extension_manager - beartype.roar.BeartypeDoorHintViolation: Callable estensione.manager.ExtensionManager.preload_extension() local variable "extension" val...

Ok, thats a lot of stuff that has no relevance and probably confuses you, so I'll stick to what's important:

E   beartype.roar.BeartypeDoorHintViolation: Callable estensione.manager.ExtensionManager.preload_extension() local variable "extension" value <class 'test_ext_4.Extension'> violates type hint estensione.extension.BaseExtension | None, as <class "abc.ABCMeta"> <class 'test_ext_4.Extension'> not <class "estensione.extension.BaseExtension"> or <class "builtins.NoneType">.

This can be translated easily over to my example:

E   beartype.roar.BeartypeDoorHintViolation: Callable some_function() local variable "x" value <class 'Bar'> violates type hint Foo | None, as <class "abc.ABCMeta"> <class 'Bar'> not <class "Foo"> or <class "builtins.NoneType">.

So what it's trying to scream at me is that I can't use Foo for my catch all type handling. I could just remove my types here and it work but that feels like cheating. Any thoughts?

If it matters, here's the actual values in the project that gave the issue:

from estensione import BaseExtension, ExtensionManager


class Extension(BaseExtension):
    def __init__(self, context: ExtensionManager) -> None:
        # Meant to fail instantiation
        1 / 0
# The insufferable test_ext_4.Extension

from abc import ABC, abstractmethod

class BaseExtension(ABC):
    """Extension Docstring"""

    name: str = "BaseExtension"
    author: str = "None"
    version: str = "0.0.1"
    dependencies: list[str] = []

    def __init__(self, context: "ExtensionManager") -> None:
        pass

    def notify(self, event: Event) -> None: ...

    @abstractmethod
    def kill(self) -> None: ...

leycec · 2025-03-05T05:27:08Z

leycec
Mar 5, 2025
Maintainer

Guh. Abstract base class horror shows, huh? Please, Gods... Let this not be the Multiple Inheritance Diamond Problem! 😱

Actually, I can't replicate this. I feel great relief, whereas you now feel great trepidation. Given this minimal-working example, we clearly see that @beartype still correctly type-checks ABCs:

from abc import ABC
from beartype.door import die_if_unbearable

class Foo(ABC): ...
class Bar(Foo): ...

x = Bar()
die_if_unbearable(x, Foo)
print("I'm OK! You're OK! @Moosems isn't OK! But that's gotta be OK!")

...which prints:

I'm OK! You're OK! @Moosems isn't OK! But that's gotta be OK!

In other words, x is indeed an instance of Foo as expected.

In your elongated example, I note that your Extension subclass fails to concretely implement the abstract superclass BaseExtension.kill() method. Could that be the issue? Probably not. Who knows what the issue here is. If you manage to drum up another minimal working example, hit me with your best copy-paste and we'll sort your code out straightaway. Your days are numbered, broken code! 🤫

Well done, by the way. Every type hierarchy needs a kill() method. We could all do with a great more murder-hoboing in our types.

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ABCMeta issue #506

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Moosems Mar 4, 2025

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leycec Mar 5, 2025 Maintainer

Moosems
Mar 4, 2025

leycec
Mar 5, 2025
Maintainer