Subject: [boost] Suggested change to type_traits/function_traits
From: Joseph Garvin (joseph.h.garvin_at_[hidden])
Date: 2010-07-13 14:12:28
I only just now subscribed to this list so forgive me if this has been
suggested and rejected before.
Currently function_traits<F> exposes the argument types for F as
individual typedefs, arg1_type, arg2_type, etc. I think this could be
made more powerful with two changes:
1. First, change it to be 0 indexed, arg0_type should be first. This
is more consistent with the rest of boost and C++ in general.
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.