Hi,
2. Have an inner arg struct, templated over an integer indicating which argument you want. So instead of:
typedef some_type arg0_type; typedef some_other_type arg1_type; //...
You would have:
template<int i> struct arg
template<> struct arg<0> { typedef some_type type; }
template<> struct arg<1> { typedef some_other_type type; }
// etc.
I think this would make function_traits more usable for metaprogramming. As is, to access the different argN_types you have to resort to using boost preprocessor. For backwards compatibility the old interface could co-exist with the new one.
The Boost function_types library which I'm using since yesterday is more like this (but not exactly like this) and defining meta-functions and MPL sequences. Besides that it has the advantage that it works for both normal functions and for member functions. Regards, Barend