Iterator for Custom Sequence

[Denis S. Otkidach]

On 16 Jul 2002, Patrick W wrote:

PW> To learn how to provide iterators for custom sequences, I've
PW> made a
PW> typical linked list with the following __iter__ method:
PW>
PW> class LinkedList:
PW>     ....
PW>     def __iter__(self):
PW>         def genitems(ls):
PW>             n = ls.head
PW>             while n.data is not None:
PW>                 yield n.data
PW>                 n = n.next
PW>         return genitems(self)
PW>     ....

__iter__ method can be implemented as generator itself:

class LinkedList:
    ...
    def __iter__(self):
        n = self.head
        while n.data is not None:
            yield n.data
            n = n.next
    ...

-- 
Denis S. Otkidach
http://www.python.ru/      [ru]
http://diveinto.python.ru/ [ru]