std::experimental::in_place

Defined in header <experimental/optional>
constexpr in_place_t in_place{};
(library fundamentals TS)

std::experimental::in_place is a constant of type std::experimental::in_place_t that is used to disambiguate the overloads of constructors and member functions of that take arguments (possibly a parameter pack) for in-place construction of some value.

See also

in-place construction tag
(class template)
(C++17)
a wrapper that may or may not hold an object
(class template)