Rewinding iterators

C. Scott Ananian ecmascript at cscott.net
Mon Apr 7 14:58:56 PDT 2014


It would be worthwhile to state that iterators returned by 'built-in'
functions always have the "no zombies" property (once done, stays
done), even though that can't be enforced on user-supplied iterators.
"Be generous in what you accept, rigorous in what you emit."
 --scott

On Mon, Apr 7, 2014 at 11:47 AM, Allen Wirfs-Brock
<allen at wirfs-brock.com> wrote:
> see https://bugs.ecmascript.org/show_bug.cgi?id=2003 which was the original
> issue that motivated the currently spec'ed  behavior.
>
>
>
>
>
>
> On Apr 7, 2014, at 3:30 AM, Marcus Stade wrote:
>
> Thanks for filing that! Now I also know where to file bugs, so doubly
> thanks!
>
> -- Marcus
>
>
> On Mon, Apr 7, 2014 at 10:00 AM, David Bruant <bruant.d at gmail.com> wrote:
>>
>> Le 07/04/2014 02:31, Marcus Stade a écrit :
>>
>> In section 25.1.2 of the spec it says:
>>
>>> The function returns an object that conforms to the IteratorResult
>>> interface. If a previous call to the next method of an Iterator has returned
>>> an IteratorResult object whose done property is true, then all subsequent
>>> calls to the next method of that object must also return an IteratorResult
>>> object whose done property is true,
>>
>>
>> Are there any practical reasons why the Iterator interface explicitly
>> disallows this?
>>
>> There is no good reason indeed. Worse, there is no way to enforce it on
>> user-generated iterators, so it'd be dangerous for standard iterator
>> consumers to assume such a property.
>>
>> This mention should probably be removed altogether.
>> Filed https://bugs.ecmascript.org/show_bug.cgi?id=2606
>>
>> Thanks,
>>
>> David
>
>
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