How do I correctly add type-hints to Mixin classes?

Question

Consider the following example. The example is contrived but illustrates the point in a runnable example:

class MultiplicatorMixin:

    def multiply(self, m: in         


        

Answer 1

One approach I saw in this question is type hinting the self attribute. Together with Union from the typing package, you are able to use the attributes from a class which is used together with your mixin, while still having correct type hinting for own attributes:

from typing import Union

class AdditionMixin:

    def add(self: Union[MyBaseClass, 'AdditionMixin'], b: int) -> int:
        return self.value + b


class MyBaseClass:

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

Downside is that you have to add the hint to every method, which is kind of cumbersome.