Hi Igor, What about concepts defined within a doubly nested namespace? Will that also work? Have you tested the code below with VC++? On Tue, 20 Aug 2002, igor_bashkirov wrote: igor_b> igor_b> [code igor_b> igor_b> #define BOOST_CLASS_REQUIRES(type_var, ns, concept) \ igor_b> typedef void (ns::concept <type_var>::* func##type_var##ns##concept) igor_b> (); \ igor_b> template <func##type_var##ns##concept _Tp1> \ igor_b> struct concept_checking_##type_var##ns##concept { }; \ igor_b> typedef concept_checking_##type_var##ns##concept< \ igor_b> BOOST_FPTR ns::concept <type_var>::constraints> \ igor_b> concept_checking_typedef_##type_var##ns##concept; igor_b> igor_b> end code] ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek@osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------