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inheritancepython-3.xmetaprogrammingmetaclasspython-datamodel

How to get parent classes of class in my meta class?


I have the following script:

#!/usr/bin/python3

class MyMeta(type):
    def __new__(mcs, name, bases, dct):
        print(name + " " + str(bases))
        return super(MyMeta, mcs).__new__(mcs, name, bases, dct)


class A(metaclass=MyMeta):
    def foo(self):
        pass


class B(A):
    pass


class C(B):
    def foo(self):
        pass


def main():
    pass


if __name__ == "__main__":
    main()

I get the following output:

A ()
B (<class '__main__.A'>,)
C (<class '__main__.B'>,)

But I expect it:

A ()
B (<class '__main__.A'>,)
C (<class '__main__.B'>, <class '__main__.A'>)

Where I make a mistake?


Solution

  • bases parameter list base classes listed in the class definition.

    It seems like you want class.mro:

    class MyMeta(type):
        def __new__(mcs, name, bases, dct):
            ret = super(MyMeta, mcs).__new__(mcs, name, bases, dct)
            print(name + " " + str(ret.mro()[1:-1]))
            return ret