Any interest in compile-time tribooleans? Functionality is currently limited by the fact that mpl::and_, mpl::or_, and mpl::not_ are not implemented in terms of any respective *_impl metafunction classes. (That means no nested expressions, no lambda expressions, and no 3+-arg expressions.) Any desire to change this? Cromwell D. Enage __________________________________ Yahoo! Music Unlimited Access over 1 million songs. Try it free. http://music.yahoo.com/unlimited/