#include <boost/preprocessor/control/if.hpp> #include <boost/preprocessor/tuple/eat.hpp> #define OP(a, b) (a b) #define MACRO(n) BOOST_PP_IF(n, OP, BOOST_PP_TUPLE_EAT(2))(1, 2) MACRO(0) // expands to nothing MACRO(1) // expands to (1, 2)