Hi, (CC'ing Peter and Joel) I've developed a patch after a somewhat short discussion on the users list for adding the ability to determine the number of arguments required at minimum for a bind expression. It is developed as a non-intrusive patch to bind and fusion. Basic usage is as follows: #include <boost/bind/min_arity.hpp> template<typename BindExpression> void dispatch(BindExpression const & e,boost::mpl::int_<0>) { // callable as e() } template<typename BindExpression> void dispatch(BindExpression const & e,boost::mpl::int_<1>) { // callable as e(_bi::type_at_index<arg_sequence,1>::type) } template<typename BindExpression> void fn(BindExpression e) { typedef boost::min_arity<BindExpression::type min_arity; dispatch(e,min_arity()); ] The patch is at: http://sohail.taggedtype.net/software/bind_arg_sequence_patch.tar.bz2 To apply: cd /path/to/boost/root tar -xjvf /path/to/bind_arg_sequence_patch.tar.bz2 patch -p0 < bind_arg_sequence.patch I would appreciate any comments. Currently it lacks documentation and I think the generated specializations could stand to be renamed. If you would like me to go further, please let me know. Thank you, Sohail