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std::any::emplace

From cppreference.com
< cpp‎ | utility‎ | any
template< class ValueType, class... Args >
std::decay_t<ValueType>& emplace( Args&&... args );
(1) (since C++17)
template< class ValueType, class U, class... Args >
std::decay_t<ValueType>& emplace( std::initializer_list<U> il, Args&&... args );
(2) (since C++17)

Changes the contained object to one of type std::decay_t<ValueType> constructed from the arguments.

First destroys the current contained object (if any) by reset(), then:

1) constructs an object of type std::decay_t<ValueType>, direct-non-list-initialized from std::forward<Args>(args)..., as the contained object. This overload only participates in overload resolution if std::is_constructible_v<std::decay_t<ValueType>, Args...> and std::is_copy_constructible_v<std::decay_t<ValueType>> are both true.
2) constructs an object of type std::decay_t<ValueType>, direct-non-list-initialized from il, std::forward<Args>(args)..., as the contained object. This overload only participates in overload resolution if std::is_constructible_v<std::decay_t<ValueType>, std::initializer_list<U>&, Args...> and std::is_copy_constructible_v<std::decay_t<ValueType>> are both true.

Contents

[edit] Template parameters

ValueType - contained value type
Type requirements
-
std::decay_t<ValueType> must meet the requirements of CopyConstructible.

[edit] Return value

A reference to the new contained object.

[edit] Exceptions

Throws any exception thrown by T's constructor. If an exception is thrown, the previously contained object (if any) has been destroyed, and *this does not contain a value.

[edit] Example

[edit] See also

constructs an any object
(public member function) [edit]
destroys contained object
(public member function) [edit]