Hi all, I know the Boost.Parameter allows advanced defaults when dealing with templated parameters - for templated classes. But shouldn't we have a simple interface, like this: struct default_ {}; template<class param, class default_type> struct use_default { typedef param type; }; template<class default_type> struct use_default<default_, default_type> { typedef default_type type; }; Example: template<class formatter_base = default_, class destination_base = default_, class f_ptr = default_, class d_ptr = default_ > struct logger { typedef use_default<formatter_base, formatter::base<> > ::type formatter_type; typedef use_default<destination_base, destination::base<> > ::type destination_type; typedef use_default<f_ptr, formatter_type* > f_ptr_type; typedef use_default<d_ptr, destination_type* > d_ptr_type; ... }; This way, if can specify only the params I want, specifying "default_" for the rest: logger< some_formatter> l; logger< default_, some_destination> l2; logger< some_fmt, default_, shared_ptr<some_fmt> > l3; ... Best, John -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right