Re: [boost] Interesting variadic template trick

Louis Dionne writes:

template void allow_expansion(T&&...);

template struct or_ { static constexpr bool value = !noexcept( allow_expansion((T::value ? throw : 0)...) ); };

How embarrassing; my unit test was very poor and the above trick does not seem to work. However, the following was tested more rigorously and works (with similar performance improvements): template constexpr bool all_pointers(T*...) { return true; } template constexpr bool all_pointers(T...) { return false; } template struct or_ { static constexpr bool value = !all_pointers( ((typename std::conditional::type)0)... ); }; template <> struct or_<> { static constexpr bool value = false; }; Regards, Louis Dionne