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Subject: Re: [PHP-DEV] Generators in PHP
From: smalyshev@sugarcrm.com (Stas Malyshev)

Hi!


> https://wiki.php.net/rfc/generators#yield_keyword
> https://wiki.php.net/rfc/generators#sending_values

I'm not sure $data = (yield $value) makes a lot of sense. Why we have
two variables here? Why it is only operator in the language that
requires parentheses around? All these complex parentheses rules seem
unnecessarily complicated. I'd rather do it in a more simple way: yield
in an expression means incoming yield. I.e.:
$data = yield;
foo(yield, 1, 2);
list($a, $b) = yield;

Same with:
call(yield $value) - what is the meaning of $value here? Why not just
call(yield)?

I would also not support array((yield $key => $value)) - it seems to be
really unclear how it works. I'd just have yield produce a value which
was sent, and that's it, and you could use this value in the same way
you'd use any other expression.

Only question I have here is what happens if you use yield in the middle
of function call expression, for example:
call(foo(bar(), $foo, yield, 3), baz());

We are kind of stopping the function in the middle of the function call
and going to unrelated code here, and may never return back. Where the
required cleanups, etc. should happen?

Another question is, if my function is like this:
function foo()
{
	var_dump(yield);
}

And I do: foo()->current() - what happens? Do I get null there? What
happens if after that I do send() on the same generator? In general,
interaction between incoming and outgoing yields is not very clear,
especially what happens when you combine them.

Also, small point: yield is repeatably called "statement" in the doc,
but in fact it can be both statement and expression with returning yield.

-- 
Stanislav Malyshev, Software Architect
SugarCRM: http://www.sugarcrm.com/
(408)454-6900 ext. 227