Make all variables global, PHP

Question

Is there a way to make all variables global?

Answer 1

To import all global variables incl. superglobals and clashing names of parameters into the functions scope:

extract($GLOBALS, EXTR_REFS | EXTR_SKIP);

The problem is with the superglobals here. You might want to exclude them, here is a list (PHP 5.2):

/**
 * PHP Superglobals
 */
array (
  1 => 'GLOBALS',
  2 => '_ENV',
  3 => 'HTTP_ENV_VARS',
  4 => '_POST',
  5 => 'HTTP_POST_VARS',
  6 => '_GET',
  7 => 'HTTP_GET_VARS',
  8 => '_COOKIE',
  9 => 'HTTP_COOKIE_VARS',
  10 => '_SERVER',
  11 => 'HTTP_SERVER_VARS',
  12 => '_FILES',
  13 => 'HTTP_POST_FILES',
  14 => '_REQUEST',
  15 => 'HTTP_SESSION_VARS',
  16 => '_SESSION',
)

You get the parameter variable names with get_defined_vars.

That's also the reason why the opposite is less tricky, get_defined_vars does not return the superglobals, only the local variables.

The global creates a reference to the variable of the global scope, so it's actually a local variable that is an alias to the global variable with the same name. Also some local vars are clashing to export, so some pre-cautions like esoteric variable names should be taken:

foreach(get_defined_vars() as ${"\x00\x00"} => ${"\x00\x01"})
{
    $GLOBALS[${"\x00\x00"}] =&$${"\x00\x00"};
}

Note that like globals the $GLOBALS superglobal array contains references to the global variables as well, so this creates references here as well. This is especially needed if you import via global or &$GLOBALS[...] or the extract like above. Or if you have local variables that are aliases to private class members (don't do that ;)):

Example/Demo:

<?php
/**
 * Make all variables global, PHP
 * @link http://stackoverflow.com/q/1909647/367456
 */
error_reporting(~0);

function bar($goo = 1)
{
    global $foo;

    $foo++;
    $baz = 3;

    foreach(get_defined_vars() as ${"\x00\x00"} => ${"\x00\x01"})
    {
        $GLOBALS[${"\x00\x00"}] =&$${"\x00\x00"};
    }
}

$foo = 1;
bar();
echo '$goo: ', var_dump($goo); # int(1)
echo '$foo: ', var_dump($foo); # int(2)
echo '$baz: ', var_dump($baz); # int(3)

Answer 2

It doesn't matter what you're trying to do, but this is a bad way of going about it. You'll be much better off just passing variables as arguments to functions or by declaring them global there.

but in short, there is no simple way to do it without a lot of global statements.