public function getDriver()
    {
        if(!$this->__driver instanceof DatabaseDriverInterface)
        {
            $this->__driver = $this->getObject($this->__driver);

            if(!$this->__driver instanceof DatabaseDriverInterface)
            {
                throw new \UnexpectedValueException(
                    'Driver: '.get_class($this->__driver).' does not implement DatabaseDriverInterface'
                );
            }
        }

        return $this->__driver;
    }