public static function static_function($plugin, $function) {
        global $CFG;

        //check that the plugin exists
        $typedirectory = $CFG->dirroot . '/repository/'. $plugin . '/lib.php';
        if (!file_exists($typedirectory)) {
            //throw new repository_exception('invalidplugin', 'repository');
            return false;
        }

        $args = func_get_args();
        if (count($args) <= 2) {
            $args = array();
        } else {
            array_shift($args);
            array_shift($args);
        }

        require_once($typedirectory);
        return call_user_func_array(array('repository_' . $plugin, $function), $args);
    }