I am trying to use inheritance in which I have a base class, say X, and 2 classes which both independently inherit from X, say A(X) and B(x) (these represent the common attributes of a whole bunch of tertiary classes, A1(A), A2(A), B1(B), etc.)

I then have some classes which ideally would inherit from both A and B, i.e., AB(A, B). Thus creating a “diamond-shaped” inheritance. But Python doesn’t seem to like this (see example below).

Why is this? Is this a bug? Does anyone know how to work around this? The example I have given is obviously extremely over-simplified, but I have a case in which I need to execute this sort of “diamond-shaped” inheritance, but it doesn’t seem to work.

I am using Python 3.11.6

For example, consider the following:

# main.py
class X:

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


class A(X):

    def __init__(self, a, x):
        self.a = a
        super().__init__(x)


class B(X):

    def __init__(self, b, x):
        self.b = b
        super().__init__(x)


class AB(A, B):

    def __init__(self, a, b, x):
        A.__init__(self, a, x)
        B.__init__(self, b, x)


ab = AB("a", "b", "x")

This fails with the following exception:

Traceback (most recent call last):
  File "main.py", line 28, in <module>
    ab = AB("a", "b", "x")
         ^^^^^^^^^^^^^^^^^
  File "main.py", line 24, in __init__
    A.__init__(self, a, x)
  File "main.py", line 11, in __init__
    super().__init__(x)
TypeError: B.__init__() missing 1 required positional argument: 'x'

As you can see, the super() inside A.__init__() refers to B, even though

issubclass(A, B) == False