#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())(1, 2)
MACRO(0) // expands to nothing
MACRO(1) // expands to (1, 2)
Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at www.boost.org/LICENSE_1_0.txt)