如何在 Python 中键入用于多个子类方法的装饰器

Question

代码是这样的，我尝试输入g，它是用作A子类的方法f的装饰器。 f 有预定义接口，所以我想避免使用 typing.Any

from typing import Callable, Type, Union


def g(func: Callable[[A], int]) -> Callable[[A], int]:
    # do stuff and return a new callable.
    ...

class A:
    def __init__(self) -> None:
        self.a = 1

class B(A):
    def __init__(self) -> None:
        self.a = 2

    @g
    def f(self) -> int:
        return self.a


class C(A):
    def __init__(self) -> None:
        self.a = 3

    @g
    def f(self) -> int:
        return self.a

上面给出了这个错误

mypy tmp.py
tmp.py:14:6: error: Argument 1 to "g" has incompatible type "Callable[[B], int]"; expected "Callable[[A], int]"
tmp.py:23:6: error: Argument 1 to "g" has incompatible type "Callable[[C], int]"; expected "Callable[[A], int]"
Found 2 errors in 1 file (checked 1 source file)

在这种情况下，输入 g 的正确方法是什么？

Answer 1

TypeVar 可用于您的情况：

from typing import Callable, TypeVar

T = TypeVar('T', bound='A')

def g(func: Callable[[T], int]) -> Callable[[T], int]:
    # do stuff and return a new callable.
    ...

class A:
    def __init__(self) -> None:
        self.a = 1

class B(A):
    def __init__(self) -> None:
        self.a = 2

    @g
    def f(self) -> int:
        return self.a


class C(A):
    def __init__(self) -> None:
        self.a = 3

    @g
    def f(self) -> int:
        return self.a

如何在 Python 中键入用于多个子类方法的装饰器

How to type a decorator that's used for methods of multiple subclasses in Python

python

class

typing

mypy