public function getManager() {
        if ($this->manager === null || !$this->manager instanceof Om\xPDOManager) {
            $managerClass = '\\xPDO\\Om\\' . $this->config['dbtype'] . '\\xPDOManager';
            $this->manager= new $managerClass($this);
            if (!$this->manager) {
                $this->log(xPDO::LOG_LEVEL_ERROR, "Could not load xPDOManager class.");
            }
        }
        return $this->manager;
    }