Iterators

Definitions

An iterator is an object that returns the next element of an iterable. The most common iterables are sequences or generators.

An iterable object is an object that implements __iter__, which is expected to return an iterator object. An iterator object implements __next__, which is expected to return the next element of the iterable or raise a StopIteration when no more elements are available.

Iterating over a collection

Basic principle:

class MyClass:
    def __iter__(self):
        self._current_value = 0
        return self

    def __next__(self):
        try:
            value = self.students[self._current_value]
            self._current_value += 1
            return value
        except IndexError:
            raise StopIteration("End of collection")