c++17

I would like to understand how deductions guides work with universal references and std::forward , in particular to create perfectly forwarding wrappers. The code below provides a code to experiment with a functor wrapper in two cases: one with an implicit deduction guide and one with an explicit deduction guide. I have put a lot of && and std::forward in comments, because I do not know where they are needed to achieve perfect forwarding. I would like to know where to put them, and where they are not needed. // Case with not conversion constructor template <class F> struct functor1 { explicit

In this Q&A I wrote a little wrapper class that provides reverse iterator access to a range, relying on the c++1z language feature template argument deduction for class templates ( p0091r3 , p0512r0 ) #include <iostream> #include <iterator> #include <vector> template<class Rng> class Reverse { Rng const& rng; public: Reverse(Rng const& r) noexcept : rng(r) {} auto begin() const noexcept { using std::end; return std::make_reverse_iterator(end(rng)); } auto end() const noexcept { using std::begin; return std::make_reverse_iterator(begin(rng)); } }; int main() { std::vector<int> my_stack; my

std::byte is an abstraction that is supposed to provide a type safe(r) access to regions of memory in C++, starting with the new standard 17. However, it's declared this way according to http://en.cppreference.com/w/cpp/types/byte : enum class byte : unsigned char {} ; That is, it is an enum class without any enumerations. Since usually the purpose of enums is to provide a restricted set of enumerations, this seems a bit strange. A class with a private unsigned char member seems like the more obvious way to do this. Why is it done this way? A class with an unsigned char member would not be