python: iterables and iterators

A class with __iter__() method or __getitem__() method is iterable. The __iter__() method returns an iterator. A iterator object has a next() method (or __next__() method in python 3.0).

class Iterator(object):
    def next(self):
        pass

class Iterable(object):
    def __iter__(self):
        return Iterator()

see also

• Build a Basic Python Iterator
• What makes something iterable in python
• Understanding Python's iterator, iterable, and iteration protocols — what exactly are they?