Re: [boost] Tick: Trait instrospection and concepts library now for C++11

Subject: Re: [boost] Tick: Trait instrospection and concepts library now for C++11
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2014-06-05 02:37:38

Le 05/06/14 07:53, paul Fultz a écrit :
> Hi,
>
> I've just update the Tick library to support C++11 compilers including support
> for gcc 4.6:
>
> https://github.com/pfultz2/Tick
>
> To support gcc 4.6 an additional `TICK_RETURNS` macro was added. So while this
> can be written for gcc 4.7 or later:
>
>      TICK_TRAIT(is_incrementable)
>      {
>          template<class T>
>          auto requires_(T&& x) -> TICK_VALID(
>              returns<int>(x++)
>          );
>      };
>
> This can be written in order to support gcc 4.6:
>
>      TICK_TRAIT(is_incrementable)
>      {
>          template<class T>
>          auto requires_(T&& x) -> TICK_VALID(
>              TICK_RETURNS(x++, int)
>          );
>      };
>
> Of course, the macro is optional and only needed to support older compilers.
>
> Any other feedback would be appreciated.
>
>
Hi,

Does your library define just traits or try to emulate Concept Lite?

In this post concepts_at_[hidden] "[concepts] Can Concepts Lite be used 
to conditionally disable a copy constructor?" there are a couple of 
questions related to your library.

* Can these traits be used to conditionally disable a constructors? an 
assignment?

class NonCopyable
{
     NonCopyable(NonCopyable const&) = delete;
};

template <typename T>
class wrapper
{
     wrapper(const wrapper&)
         requires std::is_copy_constructible<T>::value {}
};

* Can non-template members of template class be overloaded by only 
requires clause? I mean is the following examples correct (assuming that 
C1 and C2 are concepts):
template<typename T>
struct A
{
    A(const A&) requires C1<T> { /*...*/ };
    A(const A&) requires C2<T> { /*...*/ };
};

How the refinements plays on this concern?
What are the limitations respect ConceptLite?

Best,
Vicente