Re: [boost] [config][mpl][type_traits][integer] BOOST_STATIC_CONSTANT should use constexpr

Le 22/04/13 16:24, Krzysztof Czainski a écrit :

2013/4/22 Vicente J. Botet Escriba

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Out of curiosity, can you detect the difference? What can you do with

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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 a; constexpr int f();

template <int I> void g();

template <typename F> void h(F&& fct) { g(); } 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?

Really?? I thought a static constant can be used in constexpr functions, just like in C++03 it could be used as a non-type template parameter or static array size. Am I wrong here?

You are right, but I was not using an static constant but a static function. Best, Vicente