[Python-ideas] Add lookahead iterator (peeker) to itertools

[Antoine Pitrou]

On Mon, 25 Feb 2013 13:58:59 +0200
Serhiy Storchaka <storchaka at gmail.com>
wrote:
> On 25.02.13 12:07, Antoine Pitrou wrote:
> > Le Sun, 24 Feb 2013 22:41:48 -0500,
> > Terry Reedy <tjreedy at udel.edu> a écrit :
> >>
> >> def test_lookahead():
> >>       it = lookahead('abc')
> >>       while it:
> >>           a = it.peek
> >>           b = next(it)
> >>           print('next:', b, '; is peek:', a is b )
> >
> > def test_lookahead():
> >      it = iter('abc')
> >      while True:
> >          it, peeking = itertools.tee(it)
> 
> This should be outside a loop.

Only if you restrict yourself to access peeking each time you access it.
(which, I suppose, is not the general use case for the lookahead
proposal)

Regards

Antoine.