CODEWITHSUNDEEP
pythonpython-3.xinheritanceabstract-classabstract-methods
CypherX
CypherX

Reputation: 7353

How to overwrite abstract method of a child class of a super class, from the inheriting class?

I have a class KA, which has two methods, add() and subtract(), and an abstract child class KAX. KAX has an abstract method, multiply(). There is another class KB which inherits KA, and by extension has access to KAX.multiply(). I would like to overwrite/define KAX.multiply() from class KB. How to do this?

So far what I could think of is define a private method __multiply() under class KB, and then redefine under KB.__init__() as follows: 

self.KAX.multiply = self.__multiply()

This works. However, I am wondering if there is a better way to do what I am trying to achieve here. Thank you.

My current code: 

from abc import ABC, abstractmethod

class KA():

    def __init__(self):
        self.A = 3
        self.B = 10
        self.C = self.B**self.A

    @abstractmethod
    def add(self): pass

    @abstractmethod
    def subtract(self): pass

    class KAX(ABC):

        @abstractmethod
        def multiply(self): pass


class KB(KA):

    def __init__(self, A = 3, B = 10):
        #super(KB, self).__init__()
        self.A = A
        self.B = B
        self.KAX.multiply = self.__multiply
        self.KAX.multiply()
        self.C = self.KAX.multiplication

    def add(self):
        self.addition = self.A + self.B

    def subtract(self):
        self.subtraction = self.A - self.B

    def __multiply(self):
        self.KAX.multiplication = self.A*self.B


if __name__ == '__main__':
    kb = KB(A = 4, B = 2)
    # check values of variables: A, B, C
    print('Parameters: A, B, C')
    print(''.join(['kb.{}: {}\n'.format(vname, getattr(kb,vname)) for vname in ['A', 'B', 'C']]))
    # apply methods
    kb.add()
    kb.subtract()
    kb.KAX.multiply()
    # show results
    result_string = 'Result: \n\t addition: {}\t | subtraction: {}\t | multiplication: {}'
    print(result_string.format(kb.addition, kb.subtraction, kb.KAX.multiplication))

The output of this code results in: 


    Parameters: A, B, C
    kb.A: 4
    kb.B: 2
    kb.C: 1000

    Result: 
         addition: 6     | subtraction: 2    | multiplication: 8

Upvotes: 0

Views: 395

Answers (2)

Joseph Feld
Joseph Feld

Reputation: 11

Maybe you could try making a new class called KB.KAX that extends KA.KAX and then implementing your method like so:

class KA():
    class KAX():  
        @abstractmethod
        def multiply(self): pass

class KB(KA):
    class KAX(KA.KAX):
        def multiply(self):
            print("doing stuff")

Upvotes: 1

ForceBru
ForceBru

Reputation: 44858

KAX isn't a child class, it's just a class defined within another class. So, you can subclass it and override its methods:

class KB(KA):
    class KAX(KA.KAX):
        def multiply(self):
            print("hello!")

Upvotes: 1

Related Questions