std::any::emplace

C++

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Language support library

Concepts library (C++20)

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Utilities library

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Regular expressions library (C++11)

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Technical Specifications

Utilities library

Type support (basic types, RTTI, type traits)
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initializer_list (C++11)
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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
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pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
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swap
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std::any

Member functions

any::any

any::~any

any::operator=

Modifers

any::emplace

any::reset

any::swap

Observers

any::has_value

any::type

Non-member functions

swap(std::any)

any_cast

make_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.

Template parameters

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

Return value

A reference to the new contained object.

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.

See also

(constructor)	constructs an any object (public member function)
reset	destroys contained object (public member function)