Chief Delphi - An error when inheriting Joystick

There are cases in our code when we use the negated value of the Y-axis for a Joystick. I know this is (really) easy to do, but for convenience, I'd love to extend the Joystick class to include a member function that would do it automatically—I think the resultant code would read a little more intuitively.

So I tried writing this:

Code:

#include "WPILib.h"



// some code...



class MyNewAndImprovedJoystickClass : public Joystick

{

public:

        virtual float GetNegativeY() //

        {

                return -GetY();

        }

};



// more code...

But WindRiver returned the following error:

Quote:

C:/WindRiver/2013/SimpleTemplate/MyRobot.cpp:33: error: base `Joystick' with only non-default constructor in class without a constructor

And, well, I'm not sure what that means.

I understand that this issue on its own is an unimportant one. But I'm doing something wrong, and I'd like to know why. Besides, knowing more about C++ and WPILib can't hurt me.

Edit:
I found a WPILib-extending library that includes an extended Joystick class. After looking there, I tried rewriting the class as follows, and built without error:

Code:

class MyNewAndImprovedJoystickClass : public Joystick

{

public:

        MyNewAndImprovedJoystickClass(UINT32 port) : Joystick(port) {}



        virtual float GetYAdj()

        {

                return -GetY();

        }

};

I haven't tested this on the robot yet, but here's hoping.