Difference between revisions of "cpp/utility/in place"
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Revision as of 03:03, 6 April 2023
| Defined in header <utility>
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| struct in_place_t { explicit in_place_t() = default; |
(since C++17) | |
| template< class T > struct in_place_type_t { |
(since C++17) | |
| template< std::size_t I > struct in_place_index_t { |
(since C++17) | |
std::in_place, std::in_place_type, and std::in_place_index are disambiguation tags that can be passed to the constructors of std::expected, std::optional, std::variant, and std::any to indicate that the contained object should be constructed in-place, and (for the latter two) the type of the object to be constructed.
The corresponding type/type templates std::in_place_t, std::in_place_type_t and std::in_place_index_t can be used in the constructor's parameter list to match the intended tag.
See also
| (C++23) |
a wrapper that contains either an expected or error value (class template) |
| (C++17) |
a wrapper that may or may not hold an object (class template) |
| (C++17) |
a type-safe discriminated union (class template) |
| (C++17) |
objects that hold instances of any CopyConstructible type (class) |
