/**
  * Очистить кэш
  *
  * @param string $pattern
  */
 public static function clearCache($pattern)
 {
     if (is_null(self::$_cache)) {
         self::$_cache = new Doctrine_Cache_Memcache(array('servers' => array('host' => 'localhost', 'port' => 11211, 'persistent' => true), 'compression' => false));
     }
     self::$_cache->delete($pattern);
 }