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我正在尝试__new__在 Python 的元类中键入该方法，以便它使 mypy 满意。代码将是这样的（取自pep-3115 - “Python 3000 中的元类”并精简了一点）：

from __future__ import annotations

from typing import Type


# The metaclass
class MetaClass(type):

    # The metaclass invocation
    def __new__(cls: Type[type], name: str, bases: tuple, classdict: dict) -> type:
        result = type.__new__(cls, name, bases, classdict)
        print('in __new__')
        return result


class MyClass(metaclass=MetaClass):
    pass

有了这个，mypy 抱怨说，Incompatible return type for "__new__" (returns "type", but must return a subtype of "MetaClass")，指着线def __new__。

我也试过：

def __new__(cls: Type[MetaClass], name: str, bases: …