public function getCacheManager($class= 'xPDO\\Cache\\xPDOCacheManager', $options = array('path' => XPDO_CORE_PATH, 'ignorePkg' => true)) {
        if ($this->cacheManager === null || !is_object($this->cacheManager) || !($this->cacheManager instanceof $class)) {
            if ($this->cacheManager= new $class($this, $options)) {
                $this->_cacheEnabled= true;
            }
        }
        return $this->cacheManager;
    }