Macro overloading - c++

Question

Is it possible to define something like this:
#define FOO(x, y) BAR()
#define FOO(x, sth, y) BAR(sth)
so that this:
FOO("daf", sfdas);
FOO("fdsfs", something, 5);
is translated to this:
BAR();
BAR(something);
?
Edit:
Actually, BAR's are methods of my class. Sorry for not saying that before (didn't think it was relevant).
Answering DyP's question:
class Testy
{
public:
void TestFunction(std::string one, std::string two, std::string three)
{
std::cout << one << two << three;
}
void AnotherOne(std::string one)
{
std::cout << one;
}
void AnotherOne(void)
{
std::cout << "";
}
};
#define PP_NARG(...) PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
#define PP_ARG_N(_1, _2, _3, N, ...) N
#define PP_RSEQ_N() 3, 2, 1, 0
// macro for exactly 2 arguments
#define FOO_2(_1, _2) AnotherOne()
// macro for exactly 3 arguments
#define FOO_3(_1, _2, _3) AnotherOne(_2)
// macro selection by number of arguments
#define FOO_(N) FOO_##N
#define FOO_EVAL(N) FOO_(N)
#define TestFunction(...) FOO_EVAL(PP_NARG(__VA_ARGS__))(__VA_ARGS__)
And call:
Testy testy;
testy.TestFunction("one", "two", "three"); // line 9
Compiler output:
Warning 1 warning C4003: not enough actual parameters for macro 'PP_ARG_N' main.cpp 9
Warning 2 warning C4003: not enough actual parameters for macro 'FOO_' main.cpp 9
Error 3 error C2039: 'FOO_' : is not a member of 'Testy' main.cpp 9

Answer 1

Edit ------------------------------------------------look here----------------------------------------------------------------->
(Overloading macro on number of arguments)
// functions, or macros, ....
void bar(){}
void bar(int){}
#define EXPAND(X) X // for MSVC10 compatibility
// compute number of (variadic) macro arguments
// from http://groups.google.com/group/comp.std.c/browse_thread/thread/77ee8c8f92e4a3fb/346fc464319b1ee5?pli=1
#define PP_NARG(...) EXPAND( PP_NARG_(__VA_ARGS__, PP_RSEQ_N()) )
#define PP_NARG_(...) EXPAND( PP_ARG_N(__VA_ARGS__) )
#define PP_ARG_N(_1, _2, _3, N, ...) N
#define PP_RSEQ_N() 3, 2, 1, 0
// macro for exactly 2 arguments
#define FOO_2(_1, _2) bar()
// macro for exactly 3 arguments
#define FOO_3(_1, _2, _3) bar(_2)
// macro selection by number of arguments
#define FOO_(N) FOO_##N
#define FOO_EVAL(N) FOO_(N)
#define FOO(...) EXPAND( FOO_EVAL(EXPAND( PP_NARG(__VA_ARGS__) ))(__VA_ARGS__) )
int main()
{
int something = 42;
FOO("daf", sfdas);
FOO("fdsfs", something, 5);
}
Preprocessor output:
void bar(){}
void bar(int){}
int main()
{
int something = 42;
bar();
bar(something);
}
Edit2: Seems like VS2010 has some issues with __VA_ARGS__ and macro replacement.
UPDATE: It's ... a bug?? (also see this SO question):
#define MACRO2(PARAM0, PARAM1, ...) arg 0: >PARAM0< arg 1: >PARAM1< \
additional args: >__VA_ARGS__<
#define MACRO1(...) MACRO2(__VA_ARGS__, OTHERARG_0, OTHERARG_1)
MACRO1(ARG0, ARG1);
Preprocessor output:
arg 0: >ARG0, ARG1< arg 1: >OTHERARG_0< additional args: >OTHERARG_1<;
For a workaround, see the linked SO question. I've updated the original answer (code) above and tested it with MSVC10 -> works now.