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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Thu, 25 Oct 2012 10:36:47 -0600
Subject: Re: while expression feature proposal
To: Python <python-list@python.org>
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Xref: csiph.com comp.lang.python:32145

On Thu, Oct 25, 2012 at 1:21 AM, Thomas Rachel
<nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de>
wrote:
>> j = next(j for j in iter(partial(randrange, n), None) if j not in
>> selected)
>
>
> This generator never ends. If it meets a non-matching value, it just skips
> it and goes on.

next() only returns one value.  After it is returned, the generator is
discarded, whether it has ended or not.  If there were no valid values
for randrange to select, then it would descend into an infinite loop.
But then, so would the dropwhile and the original while loop.