[Python-Dev] Typo in itertools.dropwhile()

[Chris Monson]

Actually, I think it *is* a typo:  the last part should read that no
output is produced until the predicate becomes *false*.

- C


On 7/13/07, Raymond Hettinger <python at rcn.com> wrote:
>
> [Matthieu on itertools.dropwhile() docs]
> > Make an iterator that drops elements from the iterable as long as the
> predicate is true; afterwards, returns every element. Note,
> > the iterator does not produce any output until the predicate is true, so
> it may have a lengthy start-up time.
> >
> > It says something and then the opposite, so which one is true ?
>
>
> It is correct as written.  Given a sequence where predicate is true 1000
> times and then alternately false and true, it returns the
> part that is alternately false and true.  So, it did DROP (omit, not return,
> skip-over, etc) the first 1000 true items and it did
> return EVERY element from the first false to the end.  It did not produce
> any output for the first 1000 inputs so it took a while to
> get to the first output (the first false).  Hope that clears it up for you.
>
>
> Raymond
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