Re: Simulating Partial Specialization

From: jbandela_at_[hidden]
Date: 2000-10-02 12:21:02

Forgive me if I am misunderstanding your post, but if Iterator is a 
pointer, Iterator::value_type won't be defined. 

John Bandela

--- In boost_at_[hidden], "Boris Fomitchev" <fbp_at_s...> wrote:
> Looks like ISPTR used as a discriminator for full class
> specialization  
> will work if ISCONST used as a secondary discriminator and member 
> template classes work :
> 
> template <bool is_ptr, bool is_const>
> struct iterator_traits_helper
> {
>   template <class Iterator> class iterator_traits_base {
>     typedef typename Iterator::value_type value_type;
>     ...
>   }
> };
> 
> template<>
> struct iterator_traits_helper<true, true>
> {
>   // we know for sure this guy is const T*
>   // remove_const template is supposed to remove const -- do we 
have 
> that ???
>   template <class Iterator> class iterator_traits_base {
>     typedef typename remove_const<Iterator>::value_type value_type;
>     ...
>   }
> }; 
> 
> template <class T>
> struct iterator_traits : public 
> iterator_traits_helper::iterator_traits_base<IS_PTR<T>::Ret, 
> IS_CONST<T> > {
> };
> 
> The problem might be that VC6 might not work very well with 
typedefs 
> inside member template classes...
> 
> 
> -Boris.