Hi there, thanks Steven for your good advise. I have been making some progress but I'm stuck on one part. Here is some code that exhibits my problem. #include <boost/preprocessor.hpp> template< int i, int j > void test() {} int main() { #define S1 (1)(2)(3) #define S2 (1)(2)(3) #define FOR_EACH( r, data, elem ) BOOST_PP_CAT( elem \ , BOOST_PP_COMMA() ) #define FOR_EACH_PRODUCT(r, product) test< BOOST_PP_SEQ_FOR_EACH( FOR_EACH \ , BOOST_PP_EMPTY() \ , product \ ) >(); BOOST_PP_SEQ_FOR_EACH_PRODUCT( FOR_EACH_PRODUCT \ , (S1)(S2) \ ) return 0; } Here is what the preprocessor produces: test< 1, 1, >(); test< 1, 2, >(); test< 1, 3, >(); test< 2, 1, >(); [snip] My problem is that I cannot figure out how to get rid of the last comma? Any ideas? Thanks, Christian