[func.bind.place] (original) (raw)

20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.15 Function object binders [func.bind]

20.14.15.5 Placeholders [func.bind.place]

namespace std::placeholders { see below _1;see below _2;. . . see below _M;}

All placeholder types meet the Cpp17DefaultConstructible and_Cpp17CopyConstructible_ requirements, and their default constructors and copy/move constructors are constexpr functions that do not throw exceptions.

It is implementation-defined whether placeholder types meet the Cpp17CopyAssignable requirements, but if so, their copy assignment operators are constexpr functions that do not throw exceptions.

Placeholders should be defined as:inline constexpr unspecified _1{};

If they are not, they are declared as:extern unspecified _1;