Python3 Interface and Abstract class

abstract-python.py

import abc


class MyInterface(abc.ABC):  # Same as class MyInterface(metaclass=abc.ABCMeta)
    def __init__(self, age: int):
        print('MyInterface: init')
        self.age = age

    @abc.abstractmethod
    def load_data(self, name: str):
        # Notice abstract method can contain actual code
        print('MyInterface: load_data')
        print(f'MyInterface: age={self.age}')


class B (MyInterface):
    def __init__(self, age: int):
        super().__init__(age)
        print('B: init')

    def load_data(self, name: str):
        super().load_data(name) # Notice there is no param in super()
        print('B: load_data')


print(f'is subclass: B => MyInterface, {issubclass(B, MyInterface)}')
print(f'Method Resolution Order (MRO): {B.__mro__}')
b = B(13)
b.load_data('hahaha')
print(f'is instance: b => MyInterface, {isinstance(b, MyInterface)}')

# is subclass: B => MyInterface True
# Method Resolution Order (MRO): (<class '__main__.B'>, <class '__main__.MyInterface'>, <class 'abc.ABC'>, <class 'object'>)
# MyInterface: init
# B: init
# MyInterface: load_data
# MyInterface: age=13
# B: load_data
# is instance: b => MyInterface True