Le 21/04/13 17:45, John Maddock a écrit :
I'm not against this radical alternative, and I even like it. I don't know which compilers need the enum workaround and if Boost should support them.
The list seems to be:
VC7 and earlier Vacpp 5.02 and earlier (currently 11.1) Sunpro 5.6 and earlier. MPW all versions?
What I want is just that integral_constant use them so that all the traits in Boost conforms to the C++11 standard.
Out of curiosity, can you detect the difference? What can you do with constexpr values that you can't with static const ones?
Even if most of the uses of integral_constant is to use its member ::value integral constant defines also the operator(), so it is a nullary functor. integral_constant<int, 1> a; constexpr int f(); template <int I> void g(); template <typename F> void h(F&& fct) { g<fct()>(); } h(&f); h(a); The last sentence will not compile if the operator() is not a constexpr and it can not be a constexpr if ::value is not a consexpr, or can it? As you can see the case is not current, but who know what the user want to do with boost::integral_constant. The status quo means that it can not do the same thing that with std::integral_constant. Note that the operator() has just been proposed for C++14, but there is however the conversion operator to the value type. Best, Vicente