/** * the singleton pattern * * @return Felamimail_Backend_Cache_Imap_Message or Felamimail_Backend_Cache_Sql_Message */ public static function getInstance() { if (self::$_instance === NULL) { $adapter = Tinebase_Core::getConfig()->messagecache; $adapter = empty($adapter) ? 'sql' : $adapter; $classname = 'Felamimail_Backend_Cache_' . ucfirst($adapter) . '_Message'; self::$_instance = new $classname(); } return self::$_instance; }