See examples below: Is Boost.Contract parenthesized syntax really more complex than Boost.Parameter or Boost.Interface?
1) While I recognize the ugliness of the Boost.Contract parenthesized syntax, I think it is actually simpler than Boost.Parameter or Boost.Interface syntax because it is essentially "the usual C++ syntax with all the tokens wrapped within parenthesis".
2) It is possible to provide Boost.Contract with macros similar to ones of Boost.Parameter.
Hi, I think you are succesfully making the point that Boost.Contract syntax is no worse than that of Boost.Parameter; and since the latter made it into Boost, the syntax of Boost.Contract should be considered acceptable too. What is interesting is whether it is possible to define a function that validates contracts and allows named parameters at the same time. You already said it was possible. I paste an example from your post below. struct g { CONTRACT_CLASS( (g) ) BOOST_PARAMETER_MEMBER_FUNCTION( (void), depth_first_search, tag, (required (graph, *) ) (optional (visitor, *, boost::dfs_visitor<>()) (root_vertex, *, *vertices(graph).first) (index_map, *, get(boost::vertex_index, graph)) (in_out(color_map), *, default_color_map(num_verticies(graph), index_map)) ) ) CONTRACT_FUNCTION( (public) (template)( (typename)(graph_type) (typename)(visitor_type) (typename)(root_vertex_type) (typename)(index_map_type) (typename)(color_map_type) ) (void) (depth_firt_search)( (graph_type&)(graph) (visitor_type&)(visitor) (root_vertex_type&)(root_vertex) (index_map_type&)(index_map) (copyable)(color_map_type&)(color_map) ) (postcondition) ({ CONTRACT_ASSERT( color_map == CONTRACT_OLDOF(color_map) + 10 ); }) (body) ({ color_map += 10; std::cout << "graph=" << graph << std::endl; std::cout << "visitor=" << visitor << std::endl; std::cout << "root_vertex=" << root_vertex << std::endl; std::cout << "index_map=" << index_map << std::endl; std::cout << "color_map=" << color_map << std::endl; }) ) }; This example is for sure more complex than any Boost.Parameter or Boost.Contract. I believe it should be possible to add another set of macros that would allow defining functions with named parameters and contract verification in a more simpler manner. E.g. something like: struct g { CONTRACT_CLASS( (g) ) CONTRACT_NAMED_PARAM_FUNCTION( // a new macro (public) (void) (depth_firt_search)( (CONTRACT_NAMED_PARAM_REQUIRED_ARG(&graph) CONTRACT_NAMED_PARAM_OPTIONAL_ARG(&visitor)(boost::dfs_visitor<>()) CONTRACT_NAMED_PARAM_OPTIONAL_ARG(&root_vertex)(*vertices(graph).first) CONTRACT_NAMED_PARAM_OPTIONAL_ARG(&index_map)(get(boost::vertex_index, graph)) CONTRACT_NAMED_PARAM_OPTIONAL_ARG(copyable)(color_map_type&)(color_map) (default_color_map(num_verticies(graph), index_map)) ) (postcondition) ({ CONTRACT_ASSERT( color_map == CONTRACT_OLDOF(color_map) + 10 ); }) (body) ({ color_map += 10; std::cout << "graph=" << graph << std::endl; std::cout << "visitor=" << visitor << std::endl; std::cout << "root_vertex=" << root_vertex << std::endl; std::cout << "index_map=" << index_map << std::endl; std::cout << "color_map=" << color_map << std::endl; }) ) }; Obviously, my example is syntactically wrong and may be impossible, but I think you get the general idea. I am not sure if it is Boost's requirement that different libraries should interoperate smoothly with one another, but it would surely be elegant. I am not sure if this is achievable, as the macro tricks employed in the above libraries are beyond my comprehension. Also, it is not clear whether it should be a task for Boost.Contract maintainer or Boost.Parameter maintainer - the issue seems symmetrical. Regards, &rzej