class Db extends \PDO
{
    private $_host;
    private $_dbname;
    private $_user;
    private $_pass;
    public function __construct($config)
    {
      if(empty($config)) {
        throw new Exception('Cannot connect to database. Config array seems to be empty.');
      }
        $this->_host = $config['host'];
        $this->_dbname = $config['dbname'];
        $this->_user = $config['user'];
        $this->_pass = $config['pass'];
        $format = 'mysql:host=%s;dbname=%s;charset=utf8';
        $dsn = sprintf($format, $this->_host, $this->_dbname);
        try {
            parent::__construct($dsn, $this->_user, $this->_pass, \NULL);
            parent::setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
        } catch (PDOException $e) {
            throw new Exception('Cannot connect to database. Please check your DSN string. '.$e->getMessage(), $e->getCode());
        }
    }
}