On Fri, Jul 27, 2012 at 8:09 PM, Nikita Popov <nikita....@gmail.com> wrote: >> 5. Are multiple yields allowed? I.e. the rfc mentions something like >> yield yield $a - what that would mean? I'd allow yield only be applied >> to variable expression (lval) because double yield doesn't make sense to >> me, but maybe I miss something. > > yield yield $a would basically first yield $a and then receive some > value (via send) and yield that value again. Nothing you'd normally do > ;) It was mentioned only as a syntax ambiguity consideration. > > Actually I added some additional parenthesis requirements for yield. > For example you'd have to write the above as `yield (yield $a)` now > (which should be slightly more clear). I haven't yet reflected this > change in the RFC, but I'll add a section on it later. > >> 6. “Sending values” section seems to be missing. Especially useful would >> be to cover what happens with keys there and what is the syntax there - >> is it just "$a = yield;"? Or does it mean when yield is used in >> expression it becomes incoming yield? And, last but not least - do we >> need sending into generators at all? > > Yeah, I haven't written that section yet. But it is fairly simple: If > you go $generator->send($foo) then $foo will be the result of the > current `yield` expression. And yes, this also works with keys and > values. All of the following are valid: > > $data = yield; > $data = (yield $value); > $data = (yield $key => $value); > > The first case is the most common though. I.e. you usually use it > either as a generator or a reverse generator, not both. But doing both > is also common for cooperative multitasking etc. > > Regarding the last question: I think the feature is worth adding. It > is a very powerful concept that is hard to implement otherwise. Useful > in particular for things like parsing and multitasking. > >> 6. What happens if you send into a by-ref generator? Is the data sent >> by-ref then? What if it's an expression that can't be send by-ref? > > No, sending is always by-value. By-ref only affects the yielding part.
I now added the mentioned sections: https://wiki.php.net/rfc/generators#yield_keyword https://wiki.php.net/rfc/generators#sending_values I also added a list of error conditions: https://wiki.php.net/rfc/generators#error_conditions Sorry for the delay, Nikita -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
