[Boost-users] Re: C++ Template Metaprogramming - Exercise 2-0

Dave Abrahams wrote:

...

Actually there's a much more concise solution using the type traits library. That is, after all, the focus of the chapter.

I believe that would be:

template <typename T> struct add_const_ref { typedef add_const::type type; };

Correct me if I'm wrong.

Eric.

This will not works because does not add const to references For example: add_const::type; // type is int & and not int const & I was not expecting that but it makes sence if we compare references to const pointer: add_const::type would give int * const and not int const *. Since a reference in essentially equivalent to T * const (but without the need of an inderection to uses it) add_const does not have any effect in that case. Given that, it is trivial to modify Eric's solution to have the proper result. Philippe