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Date: Fri, 28 Jan 2005 15:46:48 -0800
Lines: 38
Subject: Re: [PHP-DEV] Using Superglobals for variable variables works
From: pollita@php.net ("Sara Golemon")

> but this does also work, atm. i'm using PHP 5.0.2 on Windows XP with
> apache 1.3 and if i call my php page with
> http://localhost/test.php?test=works it works.
>
> //test.php
> <?php
> $a = '_GET';
> echo ${$a}['test'];
> var_dump($$a);
> ?>
>
It works when you're already at the global scope, but try this:

<?php
function foo() {
  var_dump($_GET);
  $g = '_GET';
  var_dump($$g);
}

foo();
?>

The first var_dump() will work right because $_GET is a superglobal and ZE
picks it out of the global context correctly, the second var_dump() will
yield a NULL and an undefined index since it will try to access it from the
local symbol table and not find it.

Declaring a variable as superglobals is just a hint to the scripting engine
to retreive it from the global symbol table rather than the active symbol
table (Superglobals, by definition live in the global symbol table).

Your example worked because at the time the variable variable was resolved,
the global symbol table WAS the active symbol table.

-Sara