Hi All I fear I may be trying to get a square peg in a round hole, but here goes anyway... I'm trying to use the boost PreProcessor library to generate constructors with varying numbers of parameters. I've tried the following: #include <boost/preprocessor/arithmetic/inc.hpp> #include <boost/preprocessor/punctuation/comma_if.hpp> #include <boost/preprocessor/repetition.hpp> #ifndef MAX_CONCRETE_CONSTRUCTOR_PARAMS #define MAX_CONCRETE_CONSTRUCTOR_PARAMS 3 #endif #define CONCRETE_CONSTRUCTOR(Z, N, _) \ template<class R BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_PARAMS(N, class A)> \ explicit Concrete( BOOST_PP_ENUM_PARAMS(N, A) ) \ { } class Concrete { public: BOOST_PP_REPEAT(BOOST_PP_INC(MAX_CONCRETE_CONSTRUCTOR_PARAMS), CONCRETE_CONSTRUCTOR, _) }; int main() { Concrete a( 1, 2 ); return EXIT_SUCCESS; } But this gives me the following error: error C2660: 'Concrete::Concrete' : function does not take 2 arguments I have feeling I'm doing something very wrong or that can't be done. Regards Paul Paul Grenyer Email: paul@paulgrenyer.co.uk Web: http://www.paulgrenyer.co.uk Have you met Aeryn: http://www.paulgrenyer.co.uk/aeryn/? Version 0.3.0 beta now ready for download