python typing module: Mixin

Question

Is there any class under typing that behaves like a mixin?

For example

from typing import Union class A:   pass  class B:   pass  class C:   pass  class D(A, B, C):   pass  # current: ab is A or B, but not both def f(ab: Union[A, B]):     pass  # ideal: ab is A and B def f(ab: Mixin[A, B]):     pass  f(D()) 

please notice how D is instance of A and B, but also C. This would be too much of a restriction for f (since f doesn't require C) and thus, the parameter ab is not necessarily of type D but Mixin[A, B]

If the typing module doesn't provide any option, is there anything more elegant than creating my own class AB(A, B)?

Answer 1

It seem to be impossible for now.

You can find a discussion about "Intersection" type in python/typing#123 repository.

There is a similar feature on PEP-544 called Protocol, and you can merge mixins by merging mixin protocols. There is an implementation of PEP-544 called typing_extensions. Maybe you can try that with this library.