On 2014-05-01 05:10, Agustín K-ballo Bergé wrote:
On 30/04/2014 07:34 p.m., Louis Dionne wrote:
As an aside, I think your `all_t` and `any_t` metafunctions could be more efficient. I'm currently (literally right now) benchmarking different implementations for those; I will notify you if there is a better alternative.
I don't know which implementations you are considering (are they publicly available online?), but here is one I found to perform good enough:
https://github.com/eggs-cpp/tupleware/blob/draft/include/eggs/tupleware/core...
Just drop the `constexpr` since it's not actually needed and it confuses GCC. It's a bug according to my reading of [expr.unary.noexcept]/3, but I didn't have the time to investigate further yet.
Regard, Very cool, indeed. The only drawback in my eyes is that the logic of using noexcept is a bit convoluted.
That got me thinking, and here's a new version. Even faster (at least on my setup, see below), and very easy to read, I think: // ------------------------------ #include <type_traits> template<bool...> struct all_helper {}; template<bool... Bs> using all_t = std::is_same<all_helper<Bs...>, all_helper<(true or Bs)...>>; // -------------------------------- I am going to use that in sqlpp11 for the time being, see https://github.com/rbock/sqlpp11/blob/develop/include/sqlpp11/detail/logic.h Here are some adhoc measurements, using a static_assert with 65536 true bool arguments (reduced code is attached): clang++-3.2 -std=c++11 -stdlib=libc++: Roland: 0.27s Agustín: 0.73s clang++-3.4.1 -std=c++11 -stdlib=libc++: Roland: 0.30s Agustín: crashes on my machine g++-4.8 -std=c++11: Roland: 0.28s Agustín: 0.79s Adding a false at the end (asserting a false value) yields the same numbers. Thanks and best regards, Roland