CODEWITHSUNDEEP
python
num3ric
num3ric

Reputation: 696

Child function with additional conditions

Say I have the following:

class Parent(object):
    [...]
    def func(self, list):
        for item in list:
            if condition1:
                do something

class Child(Parent):
    [...]
    def func(self, list):
        for item in list:
            if condition1 and condition2:
                do something

What would be an elegant way to add condition2 to func without having to recopy the entire function? Note that I actually have two additional conditions in nested 'ifs'.

Upvotes: 1

Views: 251

Answers (4)

agf
agf

Reputation: 176760

from functools import partial

class Parent(object):
    [...]
    def func(self, list, condition = lambda item: condition1):
        for item in list:
            if condition(item):
                do something

class Child(Parent):
    [...]

    def func(self, list): 
        super(Child, self).func(list, condition = lambda item: condition1 and condition2)

if you only want to vary that one condition, or 

class Parent(object):
    [...]
    def func(self, list):
        for item in list:
            self.whatever(item)

    @staticmethod
    def whatever(item):
        if condition1:
            do something
class Child(Parent):
    [...]
    @staticmethod
    def whatever(item):
        if condition1 and condition2:
            do something

if you want to vary multiple things in the loop. do something can also be another staticmethod on Parent if that is the same in both.

Upvotes: 1

Felix Kling
Felix Kling

Reputation: 816364

Another way would be to evaluate the condition in an other method and override in the child:

class Parent(object):
    [...]
    def func(self, list):
        for item in list:
            if self.test(item):
                do something

    def test(self, item):
        return condition1

class Child(Parent):
    [...]
    def test(self, item):
        return super(Child, self).test(list) and condition2

Upvotes: 4

glglgl
glglgl

Reputation: 91017

If you have access to Parent, you could do

class Parent(object):
    [...]
    def _condition(self, whatever):
        return condition1
    def func(self, list):
        for item in list:
            if self._condition(...):
                do something

class Child(Parent):
    [...]
    def _condition(self, whatever):
        return condition1 and condition2

Upvotes: 6

m0skit0
m0skit0

Reputation: 25873

Add a new method (function) that does the comparison (returns condition1 on Parent and condition1 and condition2 on Child). You would only have to modify that function in the child class.

Sorry buy I cannot write an example because I don't know Python :P

Upvotes: 1

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