Dynamic switching between classes which contain similar functions

Question

I have a base abstract class and 2 child classes ( Reader_a and Writer_a) . I have another set of classes (reader_b,writer_b) which inherit from same base class. writer_a writer_b and reader_a and reader_b serve same purpose but handle different type of images, basically they have different backends. Is there any functionality in python by which i can switch these classes based on what Image type user inputs?

Answer 1

I'd add two factory (static) methods to the base class that would check the type and would create the right child class accordingly.

class Base:
    @staticmethod
    def create_reader(image):
        if image == 'A':
            return Reader_a()
        elif image == 'B':
            return Reader_b()
        else:
            raise Exception('Unknown image')

    @staticmethod
    def create_writer(image):
        if image == 'A':
            return Writer_a()
        elif image == 'B':
            return Writer_b()
        else:
            raise Exception('Unknown image')