How can inherit from different classes depending on a condition?

Question

I have two classes, A and B. Both have a foo method. In some cases, i wan't my class C to inherit foo (and other methods) from A in other cases from B. In the code example, C will always have the foo method from A:

class A:
    def foo(self):
        print('A.foo()')


class B:
    def foo(self):
        print('B.foo()')


class C(A, B):
    pass


C().foo()

How can i choose which foo method to inherit? like:

class C(A,B):
    def __init__(self, inherit_from):
        if inherit_from == "A":
            # inherit methods from A
        elif inherit_from == "B":
            # inherit methods from B

Answer 1

You don't want to make C a subclass, but rather a superclass, and make the decision of which type of object to create at the time you initialize the object, rather than when you define the class:

from abc import abstractmethod

class C:
    @abstractmethod
    def foo(self) -> None:
         pass

class A(C):
    def foo(self):
        print('A.foo()')

class B(C):
    def foo(self):
        print('B.foo()')

inherit_from = input("What type of C should I foo?")
if inherit_from == 'A':
    c: C = A()
elif inherit_from == 'B':
    c = B()
else:
    raise ValueError(f"unknown C subclass {inherit_from}")

c.foo()

Note that this is really only important if you're using type checking (i.e. you want to be able to guarantee that c is going to be an object that implements a foo method -- the C superclass gives you a way to do that without specifying ahead of time whether it's an A or B). If you're not using type checking, then you can just skip defining class C entirely.