TestDevice(device)

This macro adds a device to the global connectedDevices array.

Parameter

• device - The device to add to the array.

Inner Workings

Macros have 2 actually useful features. The first is the double hash mark ## which allows you to concatenate names together. The second is the single hash mark # which allows you to convert a macro parameter into a string literal. What this does is first use the ## to make a global AddDevice variable that is named the device name followed by AddDevice. So if the device is named BL, the variable will be named BLAddDevice. Next, to call the constructor, it uses the # to convert the device parameter into a string literal for the name, then uses the & operator to convert it to a pointer so that the device can be implicitly cast to a vex::device pointer because they all inherit from the vex::device class.

Which makes the actual definition look like this:

#define TestDevice(device) AddDevice device##AddDevice(#device, &device);

What all this macro craziness allows me to do is make a macro that very cleanly does what would be much more work if I had to do it manually.

//Macro style:
motor motor1 = motor(PORT1);
TestDevice(motor1);

//Cpp style:
motor motor1 = motor(PORT1);
AddDevice motor1AddDevice("motor1", &motor1);