Rereading my quick post from yesterday I notice: The visit facility could be generalized further to deduce the base type, so 'visit' is not limited to 'ast::node' arguments. We can also change the interface of 'visit' to hide all the pointers from the user (taking a reference instead and applying boost::addressof in case operator& is overloaded): namespace detail { template <class Last, class T, class Visitor> bool visit(Last, Last, T *, Visitor &) { throw "bummer"; } template <class First, class Last, class T, class Visitor> bool visit(First, Last, T * object, Visitor & v) { typedef typename mpl::deref<First>::type type; type * typed_object = dynamic_cast<type *>(object); if (! typed_object) detail::visit( typename mpl::next<First>::type() , Last() , object , v ); else v(*typed_object); } } template<class T, class Visitor> bool visit(T & object, Visitor & with_visitor) { typedef typename Visitor::accepted_types seq; return detail::visit( typename mpl::begin<seq>::type() , typename mpl::end<seq>::type() , boost::addressof(object) , with_visitor ); } Regards, Tobias