从python中的变量类继承

Question

I have a class foo that inherits from bar. However I also want to have the option when initializing foo to have it inherit from wall instead of bar. I am thinking something like this:

class Foo():
    def __init__(self, pclass):
        self.inherit(pclass)
        super().__init__()

Foo(Bar) # child of Bar
Foo(Wall) # child of Wall

Is this possible in Python?

Answer 1

It's not really possible easily, because classes are defined at the time of executing the class block, not at the time of creating an instance.

A popular design pattern to use instead would be to put the common code into a mixin :

class FooMixin:
    # stuff needed by both Foo(Bar) and Foo(Wall)

class FooBar(FooMixin, Bar):
    ...

class FooWall(FooMixin, Wall):
    ...

Then you can use some sort of factory function:

def make_foo(parent, *init_args, **init_kwargs):
    if parent is Bar:
        Foo = FooBar
    elif parent is Wall:
        Foo = FooWall
    return Foo(*init_args, **init_kwargs)