Re: [boost] [type_traits] has_equal_to< std::vector<T> > always true_

Subject: Re: [boost] [type_traits] has_equal_to< std::vector<T> > always true_
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-04-25 13:28:52

Le 25/04/12 15:02, lcaminiti a écrit :
> Frédéric Bron wrote
>>> Were these traits specialized for the STL in any of the latest Boost
>>> releases?
>> don't think so.
>>
> Do I have permission to add the specializations for STL containers to trunk
> and then the to release 1.50?
>
> 1) I'd add something like this for each STL container that defines an
> operator==:
>
>      template<  typename T, class Alloc = std::allocator<T>  >
>      struct has_equal_to<  std::vector<T, Alloc>  >  : has_equal_to<T>  {};
>
> 2) I'd add similar specializations for all traits that apply !=,<=, etc.
>
> 3) I'd add the specializations in the trait header
> type_traits/has_equal_to.hpp, etc and not into special headers
> type_traits/std/vector.hpp, .etc (because when I use has_equal_to on
> std::vector I'd always expect it to work according to the specialized
> version as a user and achieving expected behavior should require no extra
> user step like including type_traits/std/vector.hpp).
>
> I'm happy to change the code, check the regression tests, and I don't think
> any documentation needs to be changed (because the specializations just make
> the traits work as the user expects them to work).
>
> What do you think?

Why do you need to specialize this trait for STL containers? Do you mean 
that has_equal_to doesn't work for them? if no why?

Sorry if this is something obvious.

Best,
Vicente