[Django] #33415: @classproperty breakes @abc.abstractmethod

[Django]

#33415: @classproperty breakes @abc.abstractmethod
--------------------------------------+------------------------
Reporter: Behoston | Owner: nobody
Type: Bug | Status: new
Component: Utilities | Version: 4.0
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
--------------------------------------+------------------------
I'm trying to do something weird, but I found an interesting bug:

{{{
#!div style="font-size: 100%"
Example:
{{{#!python
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.

{{{
#!div style="font-size: 100%"
Example:
{{{#!python
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

}}}
}}}

--
Ticket URL: <https://code.djangoproject.com/ticket/33415>
Django <https://code.djangoproject.com/>
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[Django]

#33415: @classproperty breakes @abc.abstractmethod
----------------------------------+--------------------------------------
Reporter: Mateusz Legięcki | Owner: nobody
Type: Bug | Status: closed
Component: Utilities | Version: 4.0
Severity: Normal | Resolution: needsinfo

Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

----------------------------------+--------------------------------------
Changes (by Mariusz Felisiak):

* status: new => closed
* resolution: => needsinfo

Comment:

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?

--
Ticket URL: <https://code.djangoproject.com/ticket/33415#comment:1>