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Date: Tue, 1 Jul 2014 09:48:18 +0400
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To: Andrea Faulds <ajf@ajf.me>
Cc: Bob Weinand <bobwei9@hotmail.com>, Xinchen Hui <xinchen.h@zend.com>, 
	David Soria Parra <dsp@php.net>, Julien Pauli <jpauli@php.net>, PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Wired constant expression syntax and bug
From: dmitry@zend.com (Dmitry Stogov)

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On Tue, Jul 1, 2014 at 1:05 AM, Andrea Faulds <ajf@ajf.me> wrote:

>
> On 30 Jun 2014, at 20:06, Dmitry Stogov <dmitry@zend.com> wrote:
>
> > Hi Bob,
> >
> > I'm wondered why you introduced this wired syntax in PHP-5.6.
>
> Do you mean weird?
>

yes :) sorry


>
> >
> > class FooBar {
> >              const bar =3D ["bar" =3D> 3]["bar"];
> > }
> >
> > It wasn't a part of RFC, it wasn't covered by tests, and it actually
> > doesn't make a lot of sense. May be it's better to remove it?
>
> I disagree, it makes perfect sense:
>
> class FooBar {
>    const FOO =3D 3;
>    const BAR =3D [
>        3 =3D> =E2=80=98qux=E2=80=99,
>        4 =3D> =E2=80=98bang=E2=80=99,
>        7 =3D> =E2=80=98theta=E2=80=99,
>        9 =3D> =E2=80=98epsilon=E2=80=99
>    ][FOO];
> }
>
> ?: and ? only work when there are just two possibilities.
>

?: may work with brackets, but I have to admit that it's less readable.

class Foo {
        const X =3D 2;
        const Y =3D (Foo::X =3D=3D 0 ? 1 :
                 (Foo::X =3D=3D 1 ? 2 :
                 (Foo::X =3D=3D 2 ? 3 :
                 (Foo::X =3D=3D 3 ? 4 :
                 5))));
}

The situation is really inconsistent because we allow expressions on
constant arrays but at the same time prohibit array usage.
Look into the following scripts:


<?php
 class Foo {
   const BAR =3D [
       3 =3D> =E2=80=98qux=E2=80=99,
       4 =3D> =E2=80=98bang=E2=80=99,
       7 =3D> =E2=80=98theta=E2=80=99,
       9 =3D> =E2=80=98epsilon=E2=80=99
   ][1];
}
var_dump(Foo::BAR); // works - prints 'bang'
?>

<?php
 class Foo {
   const BAR =3D [
       3 =3D> =E2=80=98qux=E2=80=99,
       4 =3D> =E2=80=98bang=E2=80=99,
       7 =3D> =E2=80=98theta=E2=80=99,
       9 =3D> =E2=80=98epsilon=E2=80=99
   ];
}
var_dump(Foo::BAR); // doesn't work - Fatal error: Arrays are not allowed
in constants at run-time
?>

<?php
 class Foo {
   const BAR =3D [
       3 =3D> =E2=80=98qux=E2=80=99,
       4 =3D> =E2=80=98bang=E2=80=99,
       7 =3D> =E2=80=98theta=E2=80=99,
       9 =3D> =E2=80=98epsilon=E2=80=99
   ];
}
// This works again! We may declare array class constants if we don't use
them?
?>

Where is the logic?

Thanks. Dmitry.


>
> It is surprising that it wasn=E2=80=99t in the RFC though, I suspect that=
 was just
> an oversight on Bob=E2=80=99s part.
> --
> Andrea Faulds
> http://ajf.me/
>
>
>
>
>

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