Python - Add methods dynamically to a class (from another class)

add_metods_dyn.py

"""MethodType for dynamic appending methods to classes"""

from types import MethodType


class A:
    def __init__(self) -> None:
        self.n = 0

    def inc(self):
        self.n += 1

    def propagate_inc(self, class_instance):
        class_instance.inc = MethodType(A.inc, class_instance)


class B:
    def __init__(self) -> None:
        self.n = 0


if __name__ == '__main__':
    a = A()
    print(f'A(n) {a.n}')
    a.inc()
    print(f'A(n) {a.n}')
    b = B()
    print(f'B(n) {b.n}')
    a.propagate_inc(b)
    b.inc()
    print('inc?')
    print(f'A(n) {a.n}')
    print(f'B(n) {b.n}')
    b.inc()
    print(f'A(n) {a.n}')
    print(f'B(n) {b.n}')