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Protocols don't support descriptors #5481
Description
Consider this code:
class Descr:
def __get__(self, inst: Any, owner: Any) -> int: ...
class Proto(Protocol):
x: int
class C:
x = Descr()
a: Proto = C()I think it should be allowed. This can be done by simply re-using the logic in analyze_member_access in checkmember.py, see also #5136.
Activity
bryanforbes commentedon Jan 30, 2019
This will be fixed when #3832 is complete
ilevkivskyi commentedon Dec 19, 2019
This appeared again in dropbox/sqlalchemy-stubs#134
ckarnell commentedon Dec 20, 2019
Can you tell me exactly where in the code the duplication is happening WRT Protocols, so I can try to piece together some understanding and look into fixing it? I'm looking myself but it's not immediately obvious, and I'm unfamiliar with the codebase.
ilevkivskyi commentedon Dec 20, 2019
Just to set realistic expectations: it is unlikely anyone beyond core team can fix this. But anyway, the problematic logic duplication is between
is_protocol_implementation()/find_member()insubtypes.pyandanalyze_instance_member_access()incheckmember.py.ckarnell commentedon Dec 21, 2019
Got it, makes sense. I might take a peek anyway just out of curiosity.
sobolevn commentedon Jun 23, 2021
This was raised once again in
django-stubsrepo: typeddjango/django-stubs#651Use checkmember.py to check protocol subtyping (python#18943)
Use checkmember.py to check protocol subtyping (python#18943)