> -----Original Message-----
> From: Nikita Popov [mailto:[email protected]]
> Sent: 20 August 2012 14:12
> To: Ángel González
> Cc: Rasmus Lerdorf; Stas Malyshev; Derick Rethans; PHP internals
> Subject: Re: [PHP-DEV] [RFC] Generators
>
> On Mon, Aug 20, 2012 at 1:56 PM, Ángel González
> <[email protected]> wrote:
> > On 20/08/12 02:01, Rasmus Lerdorf wrote:
> >> I would still like to understand what this generator keyword
would
> >> actually do. I don't see how it would work. Would a
> function marked
> >> generator somehow not be allowed to return normally or to
> finish and
> >> not return anything? How could this be enforced? I am completely
> >> against any keyword that is essentially documentation-only.
> >>
> >> -Rasmus
> > Given that such function could "return several times", seems a
> > different enough function type to have its keyword.
> The method signature defines the API, so the caller knows what to
use.
> Can we agree on that? In this case it makes absolutely no
> difference to the caller whether the function is implemented
> using a generator, or whether it returns a custom Iterator
> object. The "generator"
> keyword wouldn't document the API, it would document an
> implementation-detail.
>
> What would *actually* make sense here are return value typehints.
E.g.
> one could have something like `public Iterator getIterator() { ...
}`.
> This would provide the caller with information on what the
> function returns, but would leave out the implementation
> detail that the Iterator was implemented using a generator.
> Or, if the generator implementation is actually important
> (because it is used as a
> coroutine) one could also explicitly typehint against it:
> `public Generator getCoroutine() { ... }`.
>
Yes. Quick example...
interface A
{
function gen();
}
class AImplementation implements A
{
function gen()
{
for($i = 0; $i < 10; ++$i)
yield $i;
}
}
class ADecorator implements A
{
private $a;
function __construct(A $a)
{
$this->a = $a;
}
function gen()
{
return $this->a->gen();
}
}
$a = new ADecorator(new AImplementation());
foreach($a->gen() as $v)
echo $v, "\n";
Obviously, AImplementation::gen() is a generator, but
ADecorator::gen() isn't, but would want both to adhere to the same
interface.
So only return type hinting makes sense.
> But return-value type hints are not directly related to generators.
> They are a more general concept. If that's what all of you
> want, then I'd recommend opening up a new thread for it.
>
> > You could not decorate it and rely instead on the presence of the
> > yield keyword, but parsers will thank knowing about it from
> the start
> > rather than realising at mid-parsing that the function is a
> completely
> > different beast.
> No, parsers don't care about this. It's trivial to detect in
> both cases.
>
> Nikita
>
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Jared
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