Closed
Description
When I check this code with mypy:
from abc import abstractmethod
from functools import total_ordering
@total_ordering
class PriorityMixin:
@abstractmethod
def getName(self) -> str: ...
@abstractmethod
def getPriority(self) -> int: ...
def __hash__(self) -> int:
return hash(self.getName())
def __eq__(self, other: object) -> bool:
if isinstance(other, PriorityMixin):
return self.getName() == other.getName()
else:
return NotImplemented
def __lt__(self, other: object) -> bool:
if isinstance(other, PriorityMixin):
prioCmp = self.getPriority() - other.getPriority()
if prioCmp == 0:
return self.getName() < other.getName()
else:
return prioCmp < 0
else:
return NotImplementedIt reports:
testcase.py:4: error: Only concrete class can be given where "Type[PriorityMixin]" is expected [misc]
@total_ordering
^
I'm using mypy 0.770 under Python 3.7.3 on openSUSE Linux.
I don't see a reason why an abstract class cannot be decorated with @total_ordering.
In typeshed commit e404e15 the signature of total_ordering was changed to preserve the original type. I think that change makes sense until full total_ordering support is implemented (#4610), but it does trigger the issue described above.
I think this issue may be a variation of #5374, since that describes a similar problem when using @dataclass as an annotation.