This code: BOOST_MPL_HAS_XXX_TRAIT_DEF(normal); template<class T, bool HasNormal> class getVertexHasNormal { public: static void getNormal(T &tv) {} }; template<class T> class getVertexHasNormal<T, true> // true case { public: static void getNormal(T &tv) { // do something } }; template<class VT> class A : public base { void doit(v) /* override */ { VT tv; getVertexHasNormal<VT, has_normal<VT>::value >::getNormal(tv); } } if I understand correctly, this code is suppose to do call a different "getNormal" method if the method "normal" exists (or not) in the template parameter class. Basically mimicking the infamous "__if_exists" macro on the Microsoft c++ compiler.... right? but, has_normal<VT> always return false (visual studio 2008) so we don't get the right expected behavior! Feel free to educate me.... thanks in advance. eric