In the page it is informed that sort has an average complexity of O(nlog n), but I'm writing this: template <typename T, typename U> struct sort_hierarchy_pred : mpl::not_< boost::is_base_and_derived<T, U> >::type { }; typedef mpl::back_inserter< mpl::vector<> > aux_in; template <typename SequenceT> struct sort_hierarchies : public mpl::sort<SequenceT, typename mpl::lambda<sort_hierarchy_pred<mpl::_, mpl::_> >::type , aux_in> {}; and for a sequence of 5 or more, the compile time and memory usage gets too huge. To became unuseable. What I'm trying to achieve is a sequence of types that are sorted with the bases first... Could anybody shed some light why and if there's some workaround this? thanks in advance, Felipe. -- Felipe Magno de Almeida Developer from synergy and Computer Science student from State University of Campinas(UNICAMP). Unicamp: http://www.ic.unicamp.br Synergy: http://www.synergy.com.br "There is no dark side of the moon really. Matter of fact it's all dark."