How would I create a custom list class in python?

Question

I would like to write a custom list class in Python (let's call it MyCollection) where I can eventually call:

for x in myCollectionInstance:     #do something here 

How would I go about doing that? Is there some class I have to extend, or are there any functions I must override in order to do so?

Answer 1

Your can subclass list if your collection basically behaves like a list:

class MyCollection(list):     def __init__(self, *args, **kwargs):         super(MyCollection, self).__init__(args[0]) 

However, if your main wish is that your collection supports the iterator protocol, you just have to provide an __iter__ method:

class MyCollection(object):     def __init__(self):         self._data = [4, 8, 15, 16, 23, 42]      def __iter__(self):         for elem in self._data:             yield elem 

This allows you to iterate over any instance of MyCollection.