in-place-t-struct-in-place-type-t-struct-in-place-index-t-struct.md

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Learn more about: in_place_t Struct, in_place_type_t Struct, in_place_index_t Struct	in_place_t Struct, in_place_type_t Struct, in_place_index_t Struct	11/04/2016	utility<in_place_t> utility/std::in_place_t utility<in_place_type_t> utility/std::in_place_type_t utility<in_place_index_t> utility/std::in_place_index_t	utility<in_place_t> struct

in_place_t Struct, in_place_type_t Struct, in_place_index_t Struct

The empty structure type in_place_t can be passed into constructors of expected class, optional class or single_view class for in-place construction of the contained type. The empty structure type in_place_type_t can be passed into constructors of any class or variant class to specify the type of the object. The empty structure type in_place_index_t can be passed into constructors of variant class to specify the index of the object.

Syntax

struct in_place_t {
    explicit in_place_t() = default;
};

inline constexpr in_place_t in_place{};

template <class T>
struct in_place_type_t {
    explicit in_place_type_t() = default;
};

template <class T>
inline constexpr in_place_type_t<T> in_place_type{};

template <size_t I>
struct in_place_index_t {
    explicit in_place_index_t() = default;
};

template <size_t I>
inline constexpr in_place_index_t<I> in_place_index{};