小编Suk*_*mbu的帖子

演示代码

#!/usr/bin/env python3

from abc import ABCMeta, abstractmethod

class Base(metaclass = ABCMeta):
    @classmethod
    def __subclasshook__(cls, subclass):
        return (
            hasattr(subclass, 'x')
        )

    @property
    @abstractmethod
    def x(self) -> float:
        raise NotImplementedError

class Concrete:
    x: float = 1.0

class Application:
    def __init__(self, obj: Base) -> None:
        print(obj.x)

ob = Concrete() 
app = Application(ob)

print(issubclass(Concrete, Base))
print(isinstance(Concrete, Base))
print(type(ob))
print(Concrete.__mro__)

python test_typing.py返回：

1.0
True
False
<class '__main__.Concrete'>
(<class '__main__.Concrete'>, <class 'object'>)

并mypy test_typing.py返回：

test_typing.py:30: error: Argument 1 to "Application" has incompatible …