std::in_place_t

 

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in_placein_place_tin_place_type_tin_place_index_t

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in_place

 

Defined in header <optional>
struct in_place_t {};		(since C++17)

std::in_place_t is an empty class type 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 in_place_t in_place_type_t in_place_index_t (since C++17)	in-place construction tag (function template)
optional (since C++17)	a wrapper that may or may not hold an object (class template)