Overview It is known that since C++11, a parameter of type T&& is called an rvalue reference [ISO/IEC 14882:2011 ยง8.3.2/p2 References [dcl.ref] ]. That is, unless T is a template parameter type or auto or a typedef for some lvalue reference type. examples: template<typename T> void foo(T&& p) { // -> T is a template … Read more
You know the classes A and B, so you know if they are movable or not and if this design is ultimately necessary. For something like std::string, it’s a waste of time changing the existing code unless you know you have a performance problem here. If you’re dealing with auto_ptr, then it’s time to rip … Read more
When and if you should use auto&& in for loops has been explained very nicely by Howard Hinnant here. This leaves the question what x in auto &&x = …expr… actually is. And it is handled as if there there were a function template definition template <class U> void f(U&& u); and the type of … Read more
Do they mean the same thing? Universal reference was a term Scott Meyers coined to describe the concept of taking an rvalue reference to a cv-unqualified template parameter, which can then be deduced as either a value or an lvalue reference. At the time the C++ standard didn’t have a special term for this, which … Read more