[byteit101]

If I did not know WPILib, your question is already answered (that is where you put the parens). However, I do know WPILib, and you are initializing the ds wrong (because you are getting an error you did not post, which are helpful, no matter how odd it may seem to you). The DS is a singleton, and so you need to initialize it based on the singleton. If you looked at the WPILib docs, you would notice the constructor is private.

..
     Relay barrel3;
     DriverStation &ds;

public:
     RobotDemo(void):
          barrel1(3),
          barrel2(4),
          barrel3(5),
          ds(*(DriverStation::GetInstance()))
     {
           GetWatchdog().SetExpiration(0.1);
     }
     void OperatorControl(void)
...