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Date: Wed, 19 May 2010 18:21:27 +0800
Message-ID: <AANLkTikxpdmpIlVB6lOJRQ7lhUzqaB9KVBy4JJfbn-0X@mail.gmail.com>
To: Frederic Hardy <frederic.hardy@mageekbox.net>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Constant and expression ?
From: datibbaw@php.net (Tjerk Anne Meesters)

On Wed, May 19, 2010 at 5:52 PM, Frederic Hardy
<frederic.hardy@mageekbox.net> wrote:
> Hello !
>>
>> AFAIK class constants are optimized for speed and therefore don't
>> support expressions; don't expect this to change any time soon ;-)
>>
>>> Is there any feature request about constant and expression ?
>>> I would like to write something like that :
>>>
>>> <?php
>>>
>>> namespace foo\bar\directories {
>>> =A0 =A0const tmp =3D __DIR__ . '/tmp';
>>> }
>>>
>>> ?>
>
> So the best solution is something like <?php
> define('foo\bar\directories\tmp', __DIR__ . '/tmp'); ?>...
> It 's strange that "define()" function can do something that the "const"
> =A0keyword can't do, even if "const" keyword evaluation is done at compil=
ation
> time and "define()" evaluation is done at runtime.

That's why there's a cost penalty to using define().

I wrote a small article that gives an idea of the speed differences:
http://shwup.blogspot.com/2010/04/about-constants.html


>
> Best regards,
> Fred.
>
> --
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
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> Fr=E9d=E9ric Hardy : Architecte d'application/Admin. syst=E8me/Ergonome
> =A0 =A0 =A0 =A0Status : En recherche d'emploi
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
>



--=20
--
Tjerk