[boost] [utility] nonconstructible

Hi, I think it would be nice to have a "nonconstructible" class to derive from similar to noncopyable. Recently I was burned by a traits class that was getting constructed. I think this should also be used for template metafunctions. I envision something like the following: struct nonconstructible { private: nonconstructible() {} } template<typename T> struct my_traits : nonconstructible { typedef int my_type; }; Chris