From Jimbojw.com

<?php //

/*
 * RawMsg.php - Adds a parser function for inserting raw messages.
 * @author Jim R. Wilson
 * @version 0.1
 * @copyright Copyright (C) 2007 Jim R. Wilson
 * @license The MIT License - http://www.opensource.org/licenses/mit-license.php 
 * -----------------------------------------------------------------------
 * Requirements:
 *     MediaWiki 1.6.x, 1.9.x, 1.10.x or higher
 *     PHP 4.x, 5.x or higher.
 * Installation:
 *     1. Drop this script (RawMsg.php) in $IP/extensions
 *         Note: $IP is your MediaWiki install dir.
 *     2. Enable the extension by adding this line to your LocalSettings.php:
 *         require_once('extensions/RawMsg.php');
 * Version Notes:
 *     version 0.1:
 *         Initial release.
 * -----------------------------------------------------------------------
 * Copyright (c) 2007 Jim R. Wilson
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy 
 * of this software and associated documentation files (the "Software"), to deal 
 * in the Software without restriction, including without limitation the rights to 
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of 
 * the Software, and to permit persons to whom the Software is furnished to do 
 * so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all 
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 
 * OTHER DEALINGS IN THE SOFTWARE. 
 * -----------------------------------------------------------------------
 */
 
# Confirm MW environment
if (defined('MEDIAWIKI')) {
 
# Credits
$wgExtensionCredits['parserhook'][] = array(
    'name'=>'RawMsg',
    'author'=>'Jim R. Wilson - wilson.jim.r<at>gmail.com',
    'url'=>'http://jimbojw.com/wiki/index.php?title=RawMsg',
    'description'=>'Adds a parser function for inserting raw messages.',
    'version'=>'0.1'
);
 
/**
 * Wrapper class for encapsulating RawMsg related parser methods
 */
class RawMsg {
 
    /**
     * Sets up parser functions.
     */
    function setup( ) {
    
        # Setup parser hook
    	global $wgParser, $wgVersion;
    	$hook = (version_compare($wgVersion, '1.7', '<')?'#rawmsg':'rawmsg');
    	$wgParser->setFunctionHook( $hook, array($this, 'parserFunction') );
    	
    	# Add system messages
    	global $wgMessageCache;
      $wgMessageCache->addMessage('rawmsg-missing-params', 'Error: <nowiki>{{#rawmsg:}}</nowiki> is missing a required parameter.');
      $wgMessageCache->addMessage('rawmsg-missing-article', 'Error: RawMsg cannot find the article [[MediaWiki:rawmsg-$1]].');
    }
    
    /**
     * Adds magic words for parser functions.
     * @param Array $magicWords
     * @param $langCode
     * @return Boolean Always true
     */
    function parserFunctionMagic( &$magicWords, $langCode='en' ) {
        $magicWords['rawmsg'] = array( 0, 'rawmsg' );
        return true;
    }
    
    /**
     * Inserts the requested raw message
     * @param Parser $parser Instance of running Parser.
     * @param String $msg Name of raw message to display.
     * @return String Receipt from parser as a result of successful insertion.
     */
    function parserFunction( $parser, $msg=null ) {
    
        # Short-circuit if no msg has been provided  
        if ($msg===null) return '<div class="errorbox">'.wfMsg('rawmsg-missing-params').'</div>';
 
        # Build title - short-circuit if doesnt exist
        $title = Title::newFromText('rawmsg-'.$msg, NS_MEDIAWIKI);
        if (!$title || !$title->exists()) return '<div class="errorbox">'.wfMsg('rawmsg-missing-article', $msg).'</div>';
        
        # Grab the content and send it through
        $article = new Article($title);
        return $parser->insertStripItem( $article->getContent(), $parser->mStripState );
    }
}
 
/**
 * Wrapper function for language magic call (hack for 1.6 
 */
 
# Create global instance and wire it up!
$wgRawMsg = new RawMsg();
$wgExtensionFunctions[] = array($wgRawMsg, 'setup');
if (version_compare($wgVersion, '1.7', '<')) {
    # Hack solution to resolve 1.6 array parameter nullification for hook args
    function wfRawMsgLanguageGetMagic( &$magicWords ) {
        global $wgRawMsg;
        $wgRawMsg->parserFunctionMagic( $magicWords );
        return true;
    }
    $wgHooks['LanguageGetMagic'][] = 'wfRawMsgLanguageGetMagic';
} else {
    $wgHooks['LanguageGetMagic'][] = array($wgRawMsg, 'parserFunctionMagic');
}
 
} # End MW Environment wrapper
//