Nette\Caching\Cache::checkCallbacks PHP Метод

    public static function checkCallbacks($callbacks)
    {
        foreach ($callbacks as $callback) {
            if (!call_user_func_array(array_shift($callback), $callback)) {
                return FALSE;
            }
        }
        return TRUE;
    }

 /**
  * Read from cache.
  * @param  string key
  * @return mixed|NULL
  */
 public function read($key)
 {
     $key = $this->prefix . $key;
     $meta = $this->memcache->get($key);
     if (!$meta) {
         return NULL;
     }
     // meta structure:
     // array(
     //     data => stored data
     //     delta => relative (sliding) expiration
     //     callbacks => array of callbacks (function, args)
     // )
     // verify dependencies
     if (!empty($meta[self::META_CALLBACKS]) && !Cache::checkCallbacks($meta[self::META_CALLBACKS])) {
         $this->memcache->delete($key, 0);
         return NULL;
     }
     if (!empty($meta[self::META_DELTA])) {
         $this->memcache->replace($key, $meta, 0, $meta[self::META_DELTA] + time());
     }
     return $meta[self::META_DATA];
 }