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Date: Tue, 14 Aug 2012 10:59:03 -0700
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To: Stas Malyshev <smalyshev@sugarcrm.com>
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Subject: Re: [PHP-DEV] [RFC] Generators
From: aaron@aaronholmes.net (Aaron Holmes)

On 8/14/12 10:36 AM, Stas Malyshev wrote:
> Hi!
>
>> That said, rewind() should behave consistently. I don't feel it makes
>> sense to have rewind() succeed at one point, and fail at another. It
>> would only cause confusion when not familiar with the behavior. Either
>> allow it, or don't. Not both.
> It does, since foreach uses rewind. So first rewind should succeed if
> you want iterators be usable in foreach. OTOH, on something like DB
> result set, next rewind does not make any sense, if you have
> non-seekable cursor, since the results consumed are gone and there's no
> way to get them back (you could rerun the query, but it might have side
> effects and nobody guarantees you'd get the same result anyway). So it
> makes sense for the generator to succeed on first rewind but fail on
> next ones. Note that generators by nature are stateful objects, so it is
> not unexpected that they would produce different result in different
> states.
>
Thanks for clarifying. It makes sense now, considering foreach's 
behavior and the generators statefulness allowing what otherwise seems 
inconsistent.
However, might it make sense to no-op instead of erroring? If generators 
allow rewind(), it would be unexpected to receive an error for calling it.