Variadic macro and trailing comma

Question

I am trying to do object-orientation in C and want to have a syntactic sugar macro for the notation

object->vtable->method(object, arg1, arg2)
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Answer 1

In this answer there is technique explained which should allow you to count the number of parameters and use object and method as the first two arguments.

Answer 2

Short answer, yes, it is possible in a portable way.

Long answer: it's complicated, and you probably don't want to implement this yourself. There are ways to count the arguments that a macro receives and then take action according to that number. P99 implements a series of macros that can help you to achieve this. If you'd implement two base macros send_2 and send_more for the two cases you could then implement send as

#define send(...)                     \
 P99_IF_LT(P99_NARG(__VA_ARGS__), 3)  \
 (send_2(__VA_ARGS__))                \
 (send_more(__VA_ARGS__))

Technically these constructs in P99 have a restriction that they can't handle more than 150 (or so) arguments to send.

BTW, you know that probably, calling a macro send is not really a good idea. Usually people prefer that macros are in all-caps. Also most of the time it is a good idea to have a name prefix that is unique to your library/package, such as AC245_SEND.