Extension:IsAllowedHook.php

This code exhibits voodoo programming techniques. The most common of these is extending an instance's class at runtime after it has been instantiated, a technique that can be used to provide additional hooks into existing code without requiring modification of code-base files. For a list of all our scripts which exhibit voodoo, see Category:Code that uses voodoo.

<?php
# Extension:IsAllowedHook
# - Started: 2007-10-09
# - Licenced under LGPL (http://www.gnu.org/copyleft/lesser.html)

if ( !defined( 'MEDIAWIKI' ) ) die('Not an entry point.' );

define( 'ISALLOWED_VERSION', '0.0.0, 2007-10-09' );

$wgExtensionCredits['parserhook'][] = array(
	'name'        => "IsAllowedHook",
	'author'      => '[http://www.organicdesign.co.nz/nad User:Nad]',
	'description' => 'Adds a new hook called "IsAllowed" which is called from the User::isAllowed method.',
	'url'         => 'http://www.organicdesign.co.nz/Extension:IsAllowedHook.php',
	'version'     => ISALLOWED_VERSION
);

# This is the earliest hook I can find after which $wgUser is an instance of the User class
$wgHooks['userCan'][] = 'wfSetupIsAllowed';
function wfSetupIsAllowed() {

	# Return unless first call
	static $first = 0;  
	if ( $first++ ) return true;
	global $wgUser;

	# Create a new User class ($User2) by extending the existing one with an overridden isAllowed method
	$User  = get_class( $wgUser );
	$User2 = $User.'2';
	eval( "class $User2 extends $User".' {
		function isAllowed( $action = "" ) {
			$result = NULL;
			wfRunHooks("IsAllowed",array( &$this, $action, &$result ) );
			return $result === NULL ? $result = parent::isAllowed( $action ) : $result;
		}
	}' );

	# Replace the $wgUser object with an identical $User2 instance
	$oldUser = $wgUser;
	$wgUser  = new $User2();
	foreach ( array_keys( get_class_vars( $User ) ) as $k ) $wgUser->$k = $oldUser->$k;

	return true;
}