[Tutor] a question about iterators

[Kent Johnson]

On Tue, Jun 17, 2008 at 1:46 AM, Christopher Spears
<cspears2002 at yahoo.com> wrote:

> I am confused by this statement:
>>>> i = iter(a)
>
> Why do I need to turn 'a' into an iterator?  Didn't I already do this when I constructed the class?

Yes, a is already an iterator.

> As a test, I tried the following:
>
>>>> for j in range(1,5):
> ...     print j, ':', a.next(j)
> ...
> 1 :
> Traceback (most recent call last):
>  File "<stdin>", line 2, in ?
>  File "<stdin>", line 13, in next
> StopIteration
>>>>
>
> Why didn't that work?

Did you make a new a or reuse the same one? The old a has reached the
end of its values so it raises StopIteration.

Note that passing parameters to next() is not part of the iterator protocol.

Kent