Hi all, A miniature project this week was started by me this week (I was bored?) to determine the minimum arity of a bind expression. On Peter's and Joel's suggestion, I made the changes non-intrusive: i.e. the listN's used to hold the argument sequence are fusion forward sequences. Currently there is no runtime component and I suspect there will need to be some generated "at" specializations, but I don't expect this to be too difficult. So anyway two-point-one questions: 1) How do I get the type of a bind expression as a metafunction (or something) so that I can have a metafunction (or something) to return the min_arity of a bind expression? 2) How do I make a patch that includes my added files? cvs diff only shows diffs to existing files 2.1) With 2) can someone help me make the fusion sequence a mpl sequence? I can't seem to get this to work properly Thanks! Sohail PS: I'm a bit shaky on the whole metafunction concept as my attempts to get the mpl book were thwarted, hence the "or something" :) Go easy on me! (Below is the current implementation of min_arity) // TODO: make this into some sort of metafunction - or something // probably will have to always have a function to deduce the bind // expression type but the rest of it can probably be moved template<int MinArity,typename BindExpression> void min_arity(BindExpression const &) { // should be a meta function of some sort typedef typename placeholders<BindExpression>::placeholders_list placeholders_list; // a list of... argument positions typedef typename result_of::transform< placeholders_list, argument_position >::type arg_positions; // the maximum element typedef typename mpl::max_element< arg_positions>::type iter; // if there are no placeholders typedef typename result_of::empty<arg_positions>::type no_placeholders; // can only dereference iterator if there were placeholders => atleast one argument position typedef typename mpl::eval_if< no_placeholders, mpl::int_<0>, mpl::deref<iter> >::type min_arity_type; BOOST_MPL_ASSERT(( boost::is_same<min_arity_type,mpl::int_<MinArity> >)); } MPL_TEST_CASE() { min_arity<0>(boost::bind(&fn_0)); min_arity<5>(boost::bind(&fn_2,_4,_5)); min_arity<1>(boost::bind(&fn_1,_1)); int a=9; min_arity<2>(boost::bind(&fn_3,a,_1,_2)); min_arity<3>(boost::bind(&fn_3,_1,_2,_3)); min_arity<4>(boost::bind(&fn_3,a,a,_4)); min_arity<9>(boost::bind(&fn_3,_7,_9,_8)); }