Question

Let’s say I have some code that creates a class:

class Item:
    def __init__(self, param1):
        do something with param1

now let’s say I have an object, ItemChild, that inherits from that class and inherits its initialization function, i.e., has some code that calls Item’s __init__ function. However, let’s say I also want it to do more in its __init__ function, and I want it to work with more parameters, i.e., param1, param2, param3, and param4. It seems like the call to the parent’s __init__ function will now be confused, since it won’t know which parameter is param1 when I pass params 1-3 into an instance of ItemChild. Is there any way to get around this, or is inheritance of the initialization method limited to that method and cannot be extended?

Answer 1

Here is the proper way to handle a scenario like this:

class Item(object):
    def __init__(self, param1):
        # do something with param1

class ItemChild(Item):
    def __init__(self, param1, param2, param3, param4):
        super(ItemChild, self).__init__(param1)
        # do something with params

Note that Item inheriting from object is important because super() only works with new-style classes.

As noted in comments, with 3.x you do not need to include the arguments to super(), you can just use super().__init__(param1).