Hi all,
Probably this is well-known and I just failed to find it in the docs and mailing list. According to the docs (http://www.boost.org/doc/libs/1_39_0/libs/mpl/doc/refmanual/integral-sequenc...): typedef seq_c<T,c1,c2,... cn> s; Semantics: s is a sequence seq of integral constant wrappers integral_c<T,c1>, integral_c<T,c2>, ... integral_c<T,cn>. Consider the following example: const int64_t max_int = integer_traits<int>::const_max; const int64_t max_int_plus_1 = max_int + 1; BOOST_MPL_ASSERT(( equal< vector_c< int64_t, 1 > , vector< integral_c< int64_t, 1 > > > )); BOOST_MPL_ASSERT(( equal< vector_c< int64_t, max_int > , vector< integral_c< int64_t, max_int > > > )); BOOST_MPL_ASSERT(( equal< vector_c< int64_t, max_int_plus_1 > , vector< integral_c< int64_t, max_int_plus_1 > > > )); The first assert passes, while the second and third fail with the following error messages (removed repetition of 2147483647l for readability): test.h:149: error: ************mpl::equal<mpl::vector_c<int64_t, 2147483647l, 2147483647l, ...>, mpl::vector<mpl_::integral_c<int64_t, 2147483647>>, is_same<true> >::************' test.h:153: error: ************mpl::equal<mpl::vector_c<int64_t, -0x00000000080000000l, 2147483647l, ...>, mpl::vector<mpl_::integral_c<int64_t, 2147483648ll>>, is_same<true> >::************' I consider these errors as a contradiction to the docs statement. Probably, I configured MPL wrong, as I see in the preprocessed code, where long is used (boost/mpl/aux_/preprocessed/gcc/vector_c.hpp) template< typename T, long C0 = LONG_MAX, long C1 = LONG_MAX, long C2 = LONG_MAX , long C3 = LONG_MAX, long C4 = LONG_MAX, long C5 = LONG_MAX , long C6 = LONG_MAX, long C7 = LONG_MAX, long C8 = LONG_MAX , long C9 = LONG_MAX, long C10 = LONG_MAX, long C11 = LONG_MAX , long C12 = LONG_MAX, long C13 = LONG_MAX, long C14 = LONG_MAX , long C15 = LONG_MAX, long C16 = LONG_MAX, long C17 = LONG_MAX , long C18 = LONG_MAX, long C19 = LONG_MAX > struct vector_c; I'm using GCC 3.4.6, on Linux-64, compiling 32-bit binary (so int and long are of same size, and boost::int64_t is bigger than long). Thanks, Maxim (to reply in private, please use FirstName.LastName at gmail.com)