Hicham Mouline wrote:

#include <iostream> #include <boost/mpl/has_xxx.hpp> #include <boost/mpl/bool.hpp>

BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_xxx, xxx, false)

struct test1 { int xxx; };

using namespace boost::mpl; int main() { std::cout<< has_xxx<test1>::value <<std::endl; return 0; }

The output is 0, while it should be 1, shouldn't it?

That macro generates a trait that looks for a nested *type* with the specified name. In your case, xxx is a data member, not a type. HTH, -- Eric Niebler BoostPro Computing http://www.boostpro.com