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

From: David Abrahams (dave_at_[hidden])
Date: 2005-01-10 10:30:12

Ben Hutchings wrote:

> Well the first attempt doesn't solve the problem because it requires an 
> extra parameter.  The second attempt solves it but I don't think you're 
> supposed to make use of other templates.  

Any solutions is allowable, though that one is not particularly elegant.

> I think the expected solution 
> would be more like this:
> 
>      template<typename T>
>      struct add_const_ref
>      {
>          typename T const & type;
>      };
> 
>      template<typename T>
>      struct add_const_ref<T &>
>      {
>          typename T & type;
>      };

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

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com