Joomla 3 plugin to override class JMenuSite

Question

I'm trying to override a class JMenuSite in libraries/cms/menu/site.php. I created a plugin system jmenusite.php

<?php
defined( '_JEXEC' ) or die( 'Restricted access' );

class plgSystemJmenusite extends JPlugin{

    public function  onAfterRoute () {
        require_once(JPATH_SITE.'/plugins/system/jmenusite/site.php');
    }
}
?>

I copied the files site.php in the folder of the plugin.

Joomla performs the original class and then gives me error:

 Fatal error: Cannot redeclare class JMenuSite

How can I override the existing class?

Answer 1

onAfterRoute event is not the one which will work for your scenario. As JMenuSite class gets loaded before this event is triggered.

You need to use onAfterInitialise event to achieve this.

Important note : With Joomla 3.4 there are some changes in the core code due to which it will not be possible to override this class in case language filter plugin is enabled. As Joomla intentionally loads this plugin to apply some language specific handling and this plugin will load JMenuSite class before any event is triggered.