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Date: Mon, 2 Mar 2015 11:41:43 +0100
CC: Daniel Lowrey <rdlowrey@php.net>,
 "internals@lists.php.net" <internals@lists.php.net>
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To: Niklas Keller <me@kelunik.com>
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Subject: Re: [PHP-DEV] [RFC Discuss] Generator Delegation
From: bobwei9@hotmail.com (Bob Weinand)

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> Am 02.03.2015 um 11:28 schrieb Niklas Keller <me@kelunik.com>:
> 2015-03-02 11:11 GMT+01:00 Bob Weinand <bobwei9@hotmail.com =
<mailto:bobwei9@hotmail.com>>:
> > Am 02.03.2015 um 01:17 schrieb Niklas Keller <me@kelunik.com =
<mailto:me@kelunik.com>>:
> >
> > 2015-03-02 0:52 GMT+01:00 Daniel Lowrey <rdlowrey@php.net =
<mailto:rdlowrey@php.net>>:
> >
> >> Hi folks,
> >>
> >> I'd like to initiate discussion on a proposal to implement =
generator
> >> delegation via the following new syntax inside generator functions:
> >>
> >>    yield * <expr>
> >>
> >> The Generator Delegation RFC is available here:
> >>
> >> https://wiki.php.net/rfc/generator-delegation =
<https://wiki.php.net/rfc/generator-delegation>
> >>
> >> This proposal is conceptually related to (and requires =
functionality
> >> proposed by) the forerunning Generator Return Expressions RFC here:
> >>
> >> https://wiki.php.net/rfc/generator-return-expressions =
<https://wiki.php.net/rfc/generator-return-expressions>
> >>
> >>
> >> Thanks for your time,
> >>
> >> Daniel
> >>
> >
> > The proposed syntax has an issue:
> >
> > <?php
> >
> > function a () {
> >    echo yield * 3;
> > }
> >
> > $a =3D a();
> > $a->send(42);
> >
> > http://3v4l.org/n1sGb#v550 <http://3v4l.org/n1sGb#v550>
> >
> > This is currently valid PHP.
> >
> > Regards, Niklas
>=20
> Hey,
>=20
> I think we could use "yield from" as operator here.
>=20
> Yes, BC. So, I won't make "from" a keyword, but rather specify an own =
token for "yield from" (T_YIELD_FROM).
> That way we have no BC break, except someone tries to yield a constant =
named "from". I think that's a really minor break =E2=80=A6 and in case =
this breaks someones code, he needs to wrap the constant in parenthesis: =
"yield (from)".
>=20
> We can have nice syntax here with a minimal break, so, then, why not?
>=20
> Thanks,
> Bob
>=20
> If those keywords can be combined to one, that would be totally fine.
> I think BC breaks are less a problem when the lexer RFC passes, but =
that shouldn't lead to a lot more keyboards being added.
> So yield from will be totally fine, it's already used in other =
languages.
>=20
> Regards, Niklas

As said, I won't add a "from" keyword. It's just the combination of =
"yield" and "from" with will be interpreted differently at lexer level.

And yes, that's how e.g. Python calls it too, hence this suggestion.

Bob=

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