いまさらながらGCC 4.5で動いたので完全なコードを：
#include <iostream> #include <utility> #include <boost/tuple/tuple.hpp> #include <boost/preprocessor/tuple/elem.hpp> #include <boost/preprocessor/tuple/rem.hpp> #include <boost/preprocessor/seq/fold_left.hpp> #include <boost/preprocessor/arithmetic/inc.hpp> #include <boost/preprocessor/stringize.hpp> template<size_t N, typename T> typename boost::tuples::element<N, T>::type & get_with_tuple_ref_folding(T & tup) { return boost::get<N>(tup); } template<size_t N, typename T> typename boost::tuples::element<N, T>::type && get_with_tuple_ref_folding(T && tup) { return std::move(boost::get<N>(tup)); } #define TIE(seq, expr) TIE_I(seq, expr, __LINE__,) #define TIE_AUTO(seq, expr) TIE_I(seq, expr, __LINE__, auto) #define TIE_I(seq, expr, id, a) TIE_II(seq, expr, id, a) #define TIE_II(seq, expr, id, a) auto && tie_tmp_ ## id = expr; BOOST_PP_TUPLE_ELEM(4, 3, BOOST_PP_SEQ_FOLD_LEFT(TIE_OP, (0, tie_tmp_ ## id , a,), seq)) #define TIE_OP(_, l, e) TIE_OP_I((e, BOOST_PP_TUPLE_REM(4)l)) #define TIE_OP_I(par) TIE_OP_II par #define TIE_OP_II(e, n, name, a, s) (BOOST_PP_INC(n), name, a, s a e(get_with_tuple_ref_folding<n>(std::forward<decltype(name)>(name)));) int main() { TIE((const int x)(const int y)(const int z), boost::tuples::make_tuple(1, 2, 3)); std::cout << x << "," << y << "," << z << std::endl; // TIE((const int a)(boost::tuples::ignore), boost::tuples::make_tuple(4, 5)); // std::cout << a << std::endl; }
1,2,3
ignoreは使えないっぽいですねぇ。
