/**
  * Return instance of this object
  *
  * @return Singleton
  * @access public
  * @static
  */
 public static function getInstance()
 {
     if (self::$oInstance == false) {
         self::$oInstance = new WPDD_Layouts_Cache_Singleton();
         self::$cache['by_id'] = array();
         self::$cache['by_name'] = array();
         //self::cache_published_layouts();
     }
     return self::$oInstance;
 }