CODEWITHSUNDEEP
pythoninheritance
AdminXVII
AdminXVII

Reputation: 1329

Skip part of superclass __init__?

I have a class which subclass another. I would like to skip a part of the initialization process, for example:

class Parent:
    __init__(self, a, b, c, ...):
        # part I want to keep:
        self.a = a
        self.b = b
        self.c = c
        ...
        # part I want to skip, which is memory and time consuming
        # but unnecessary for the subclass:
        self.Q = AnotherClass()

class Child(Parent):
    __init__(self):
        #a part of the parent initialization process, then other stuff

The two solutions I've come up with are:

Which is best, or are there better methods?

Upvotes: 2

Views: 2207

Answers (1)

Łukasz Rogalski
Łukasz Rogalski

Reputation: 23233

What about wrapping creation of Q into private method, and overriding that method in subclass?

class Parent:
    def __init__(self, a, b, c, ...):
        # part I want to keep:
        self.a = a
        self.b = b
        self.c = c
        self._init_q()

    def _init_q():
        self.Q = AnotherClass()

class Child(Parent):
    def _init_q(self):
        pass  # do not init q when creating subclass

It's not a cleanest approach, since if Child does not need Q either it shouldn't be a child of Parent, or maybe AnotherClass is misplaced (maybe it should be injected to methods which needs it) but it solves your issue without changing any of class interfaces.

Upvotes: 7

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