Re: [Boost-users] std::is_tr1_tuple<T> - how?

Markus Werle wrote:

While migrating from boost::tuple to std::tr1::tuple (pain!) I have to rewrite a lot of compile-time-magic code. Among other things I am in need of a type info

template <typename T> struct is_tr1_tuple;

Any implementation hint or proposal welcome.

This is tricky, when BOOST_HAS_TR1_TUPLE is *not* defined, then std::tr1::tuple is an alias for either boost::fusion::tuple or boost::tuple (the latter for broken Borland compilers only), so your existing metacode should work. When BOOST_HAS_TR1_TUPLE *is* defined then std::tr1::tuple is the std lib's native implementation, you could probably use function overload resolution to detect that: template char is_tr1_tuple_test(const std::tr1::tuple&); template <class T> double is_tr1_tuple_test(const T&); template <class T> struct is_tr1_tuple { static const T m_t; static const bool value = sizeof(is_tr1_tuple_test(m_t) == 1; }; In fact I think that should work for the case that BOOST_HAS_TR1_TUPLE is not defined as well? HTH, John.