Variadic macros with zero arguments

Question

I am working on a call macro,

#define CALL(f,...) FN(f)->call((ref(new LinkedList()), __VA_ARGS__))

which when called,

C         


        

Answer 1

If you're using gcc/g++ there is a way:

#define CALL(f,...) FN(f)->call((ref(new LinkedList()), ## __VA_ARGS__))

From the fine manual:

[...] if the variable arguments are omitted or empty, the `##' operator causes the preprocessor to remove the comma before it.

So gcc has an extension/hack specifically for the problem you are facing.