An iterator with look-ahead

[Paddy]

Neil Cerutti wrote:

> On 2007-01-10, Steven Bethard <steven.bethard at gmail.com> wrote:
> > Neil Cerutti wrote:
> >> For use in a hand-coded parser I wrote the following simple
> >> iterator with look-ahead.
> >
> > There's a recipe for this:
> >
> >    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/304373
> >
> > Note that the recipe efficiently supports an arbitrary
> > look-ahead, not just a single item.
> >
> >> I haven't thought too deeply about what peek ought to return
> >> when the iterator is exhausted. Suggestions are respectfully
> >> requested.
> >
> > In the recipe, StopIteration is still raised on a peek()
> > operation that tries to look past the end of the iterator.
>
> That was all I could think of as an alternative, but that makes
> it fairly inconvenient to use. I guess another idea might be to
> allow user to provide a "no peek" return value in the
> constructor, if they so wish.
>
> --
> Neil Cerutti
You could raise a different Exception, PeekPastEndEception ?
- Paddy.