mypy:如何忽略mixin中的“缺少属性”错误

我无法让mypy正确使用mixin:它一直抱怨我的mixin引用了丢失的属性。考虑这个例子:

class PrintValueMixin:
    """A mixin that displays values"""

    def print_value(self) -> None:
        print(self.value)


class Obj(PrintValueMixin):
    """An object that stores values. It needs a mixin to display its values"""

    def __init__(self, value):
        self.value = value


instance = Obj(1)
instance.print_value()

error: "PrintValueMixin" has no attribute "value"

当然,它没有“值”属性。它是一个混合体,它不应该有自己的属性!