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Date: Tue, 03 Mar 2015 11:34:29 +0000
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Subject: Re: [PHP-DEV] [RFC Discuss] Generator Delegation
From: rowan.collins@gmail.com (Rowan Collins)

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Niklas Keller wrote on 03/03/2015 10:55:
>
>     Gr, top-posting...
>
>
> Sorry, was on mobile. ;-)
>
>     However, since the existence of the word "yield" is the only thing
>     that
>     marks a coroutine now, how about using a variant of that for the final
>     value, e.g. "yield final $foo"?
>
>
> What's the final value? The last "yield"ed value or a return?

"yield final" would mark the final result of the coroutine, as opposed 
to the intermediate values passed out with a normal "yield".


> Just to give you some real world example:
> If you're using "return", it would look like that:
>
> public function getSession ($sessionId) {
>     $result = yield $this->redis->get("session.{$sessionId}")); // 
> We're waiting here until redis responded.
>     return json_decode($result);
> }

My suggestion is simply to change the keyword:

public function getSession ($sessionId) {
     $result = yield $this->redis->get("session.{$sessionId}")); // 
We're waiting here until redis responded.
     yield final json_decode($result);
}


The reasoning being that when you run getSession(42), it *doesn't* 
return the result of json_decode(), it returns a pointer to the 
coroutine's state, which you can resume later.

Actually, I don't think that example makes sense, because JSON gets sent 
out at the first yield, and then sent back in, so the caller would look 
something like this:

$foo = getSession(42);
$json_data = $foo->current();
$foo->send($json_data);
$decoded = $foo->getReturn();

But never mind, I think we both get the idea.

I understand the desire for a "final result", but I don't like reusing 
the word "return", because it's never "returned" as the result of 
running the function, it's just made available through some specific 
method/syntax.

Regards,
-- 
Rowan Collins
[IMSoP]

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