Opened 3 years ago

Closed 3 years ago

#33415 closed Bug (needsinfo)

@classproperty breakes @abc.abstractmethod

Reported by: Mateusz Legięcki Owned by: nobody
Component: Utilities Version: 4.0
Severity: Normal Keywords:
Cc: Triage Stage: Unreviewed
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

I'm trying to do something weird, but I found an interesting bug:

Example: 

import abc
import inspect

from django.utils.functional import classproperty


class A(metaclass=abc.ABCMeta):
    @classproperty
    @abc.abstractmethod
    def x(self):
        pass


print(inspect.isabstract(A))  # False

This prints False. It should print True, due to method x is not implemented.

It works a little bit better when @abc.abstractmethod is first decorator. Then class is recoginsed as abstract. However, subclass of this class is always not-abstract.

Example: 

import abc
import inspect

from django.utils.functional import classproperty


class A(metaclass=abc.ABCMeta):
    @abc.abstractmethod
    @classproperty
    def x(self):
        pass

class B(A, metaclass=abc.ABCMeta):
    pass


print(inspect.isabstract(A))  # True
print(inspect.isabstract(B))  # False

Change History (1)

comment:1 by Mariusz Felisiak, 3 years ago

Resolution: → needsinfo
Status: new → closed

Other decorators also break isabstract(), e.g. @cached_property. I'm not sure how to fix it and is it worth additional complexity. Can you provide PoC?

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