如何为PyCharm中动态生成的类添加类型提示消除Linter警告

方法1：为动态生成函数添加泛型类型提示 #

用typing.TypeVar和typing.Type定义泛型，让类型检查器明确make_augmented_class返回的是输入类的子类类型，从而识别继承的类属性。

修改后的完整代码：

from typing import TypeVar, Type

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

class MyClass(object):
    ID_NUM: int = 0

    def __init__(self, id_num: int, first_name: str, last_name: str):
        self.ID_NUM = id_num
        self.first_name = first_name
        self.last_name = last_name


def make_augmented_class(cls: Type[T]) -> Type[T]:
    def augmented__eq__(self, other):
        try:
            return self.ID_NUM == other.ID_NUM
        except AttributeError:
            return False

    new_cls = type('{}Augmented'.format(cls.__name__), (cls,), {})
    new_cls.__eq__ = augmented__eq__
    return new_cls


def do_stuff(my_class: Type[MyClass]):
    print(my_class.ID_NUM)


if __name__ == '__main__':
    do_stuff(MyClass)

    augmented_class = make_augmented_class(MyClass)
    do_stuff(augmented_class)  # Linter不再报警告

注：原代码中augmented__eq__里的self.id_num是笔误，修正为self.ID_NUM保证逻辑正确。

方法2：调用时用typing.cast强制类型转换 #

如果不想改动函数的类型注解，直接在调用do_stuff时用cast告诉Linter动态类的实际类型：

from typing import cast, Type

# MyClass和make_augmented_class代码保持不变

def do_stuff(my_class: Type[MyClass]):
    print(my_class.ID_NUM)


if __name__ == '__main__':
    do_stuff(MyClass)

    augmented_class = make_augmented_class(MyClass)
    do_stuff(cast(Type[MyClass], augmented_class))  # 强制转换类型消除警告

cast仅作用于类型检查阶段，不影响代码运行逻辑。

方法3：用Protocol定义类属性契约 #

如果需要更灵活的约束（只要类有ID_NUM属性就能传入do_stuff），可以用typing.Protocol定义契约：

from typing import Protocol, Type, TypeVar

class HasIDNum(Protocol):
    ID_NUM: int

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

class MyClass(object):
    ID_NUM: int = 0

    def __init__(self, id_num: int, first_name: str, last_name: str):
        self.ID_NUM = id_num
        self.first_name = first_name
        self.last_name = last_name


def make_augmented_class(cls: Type[T]) -> Type[T]:
    def augmented__eq__(self, other):
        try:
            return self.ID_NUM == other.ID_NUM
        except AttributeError:
            return False

    new_cls = type('{}Augmented'.format(cls.__name__), (cls,), {})
    new_cls.__eq__ = augmented__eq__
    return new_cls


def do_stuff(my_class: Type[HasIDNum]):
    print(my_class.ID_NUM)


if __name__ == '__main__':
    do_stuff(MyClass)

    augmented_class = make_augmented_class(MyClass)
    do_stuff(augmented_class)

这种方式不局限于MyClass及其子类，任何带有ID_NUM类属性的类都能传入do_stuff。

内容的提问来源于stack exchange，提问作者Roy Wood