system prototype

main.py

class NonCallable:
    #TODO: now this is a behavior, not metaclass,
    # so msg has to refer to NonCallable

    def __call__(self, *args, **kwargs):

        is_root = len(self.__mro__) ==2

        cls_name = self.__name__
        type_name = type(self).__name__


        if is_root:
            msg = '\nClass '+cls_name+'(metaclass = '+type_name+') cannot be called'
        else:
            mcs_root_name = self.get_metaclass_root().__name__
            msg = '\nClass '+cls_name+' cannot be called\nbecause it has '+mcs_root_name+'(metaclass = '+type_name+')'

        raise AttributeError(msg)

    def get_metaclass_root(self):
        return (self.__mro__[::-1][1])


class ClassAllMethods:
    def __new__(cls, name, bases, attrs):
        for method_name, method in attrs.items():
            if method_name.startswith('_'): continue
            print (method)
            attrs[method_name] = classmethod(method)
        return type.__new__(cls, name, bases, attrs)


class SystemType(NonCallable, ClassAllMethods, type):
    pass


class System(metaclass=SystemType):
    def some_method(cls):
        print('hi')


class MySystem(System):
    def some_method(cls):
        super().some_method()
        print('hi')

MySystem.some_method()