I may have posted something to this effect in Apr. 2003 but got no response if I have; just thought I might have better luck the second time as there were no changes to the tuple library since then. Proposal: current boost/tuple library has a hardcoded limit on the tuple arity (10 elements). Some applications may require substantially larger tuples even at a cost of extended compilation time. Using boost/preprocessor library, it is relatively easy to rewrite the tuple code in such a way that arity limit will depend on a single configuration macro without incuring any other changes to the library. No additional cost will be imposed on the users who are satisifed with the current tuple library. I have a working implementation of such configurable tuples that I've been using since Apr. 2003. As I had no need to support C++ compilers that do not implement partial specification, I have only converted boost/tuple/detail/tuple_basic.hpp so far. Arity limit is controlled by the BOOST_TUPLE_MAX_ARITY macro which is defaulted to 10 inside tuple_basic.hpp if it is not defined prior to its inclusion. Since I am not sure what procedure should I follow to submit such a modification to an existing Boost library, I decided just to post the proposal here and provide a link to the modifed file: http://fridge.yymap.com/files/tuple_basic.hpp Regards, ...Max...