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Date: Sun, 5 Jun 2016 14:24:01 +0200
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Subject: AW: [PHP-DEV] Re: [RFC] [PRE-VOTE] Union types
From: php@tutteli.ch ("Robert Stoll")



> -----Urspr=C3=BCngliche Nachricht-----
> Von: Ryan Pallas [mailto:derokorian@gmail.com]
> Gesendet: Sonntag, 5. Juni 2016 14:22
> An: Robert Stoll
> Cc: Bob Weinand; Andrea Faulds; internals@lists.php.net
> Betreff: Re: [PHP-DEV] Re: [RFC] [PRE-VOTE] Union types
>=20
>=20
>=20
> On Sun, Jun 5, 2016 at 6:09 AM, Robert Stoll <php@tutteli.ch> wrote:
>=20
>=20
> 	Hi Andrea, Bob
>=20
> 	> -----Urspr=C3=BCngliche Nachricht-----
> 	> Von: Bob Weinand [mailto:bobwei9@hotmail.com]
> 	> Gesendet: Sonntag, 5. Juni 2016 01:00
> 	> An: Andrea Faulds
> 	> Cc: internals@lists.php.net
> 	> Betreff: Re: [PHP-DEV] Re: [RFC] [PRE-VOTE] Union types
>=20
> 	>
> 	>
> 	> > Am 05.06.2016 um 00:55 schrieb Andrea Faulds <ajf@ajf.me>:
> 	> >
> 	> > Hi again,
> 	> >
> 	> > In an attempt to be constructive, I have implemented an =
alternative approach to weak scalar type selection
> here:
> 	> >
> 	> > =
https://github.com/krakjoe/php-src/compare/multi-types...TazeTSchnitzel:m=
ulti-types-roulette
> 	> >
> 	> > Where there is no exact scalar type match, this patch uses an =
algorithm originally suggested by Nikita, wherein
> we
> 	use
> 	> rand() to pick which type to cast to.
> 	> >
> 	> > This is much simpler than having a type precedence matrix, and =
thus is easier to remember and reason about.
> The
> 	choice
> 	> of selection function means that no particular use-case is =
privileged. Given PHP's scalar types are roughly
> equivalent
> 	(after
> 	> all, PHP juggles them freely), this apparently unorthodox selection =
process should nonetheless produce sensible
> 	results in
> 	> most cases.
> 	> >
> 	> > Please tell me your thoughts!
> 	> >
> 	> > --
> 	> > Andrea Faulds
> 	> > https://ajf.me/ <https://ajf.me/>
> 	> This is the holy grail I was hunting for so long!
> 	>
> 	> All my computational problems can be solved by a simple rand()!
> 	>
> 	> In case nobody objects I'm going to merge that straight ahead into =
php-src 7.0 (no need for master-only, after all
> 	it's no real
> 	> BC break!).
> 	>
> 	> Thanks a very much!!!
> 	>
> 	> Bob
>=20
>=20
> 	Not sure if this is a clever idea. I haven't read all emails so bear =
with me if this is more than clear. What happens
> 	with the following?
>=20
> 	function foo(int | string $a) {
> 	  if ($a =3D=3D "") {
> 	    //a
> 	  } else {
> 	    //b
> 	  }
> 	}
>=20
> 	foo(false);
>=20
> 	What branch is taken? Is it taken randomly?
>=20
>=20
>=20
> In this case, A will always be taken, because of the loose comparison =
(=3D=3D). Basically:
>=20
> var_dump("" =3D=3D ""); // bool(true)
> var_dump(0 =3D=3D ""); // bool(true)
> var_dump(false =3D=3D ""); // bool(true)
>=20

My fault, so what about=20

if ($a =3D=3D=3D "") {

}