[any.modifiers]

# 22 General utilities library [[utilities]](./#utilities)

## 22.7 Storage for any type [[any]](any#modifiers)

### 22.7.4 Class any [[any.class]](any.class#any.modifiers)

#### 22.7.4.4 Modifiers [any.modifiers]

[ð](#lib:emplace,any)

`template<class T, class... Args>
  decay_t<T>& emplace(Args&&... args);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7390)

Let VT be decay_t<T>[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7393)

*Constraints*: is_copy_constructible_v<VT> is true andis_constructible_v<VT, Args...> is true[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7398)

*Preconditions*: VT meets the [*Cpp17CopyConstructible*](utility.arg.requirements#:Cpp17CopyConstructible "16.4.4.2 Template argument requirements [utility.arg.requirements]") requirements[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7402)

*Effects*: Calls reset()[.](#4.sentence-1)

Then direct-non-list-initializes the contained value of type VT with std​::​forward<Args>(args)...[.](#4.sentence-2)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7408)

*Postconditions*: *this contains a value[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7412)

*Returns*: A reference to the new contained value[.](#6.sentence-1)

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7416)

*Throws*: Any exception thrown by the selected constructor of VT[.](#7.sentence-1)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7420)

*Remarks*: If an exception is thrown during the call to VT's constructor,*this does not contain a value, and any previously contained value
has been destroyed[.](#8.sentence-1)

[ð](#lib:emplace,any_)

`template<class T, class U, class... Args>
  decay_t<T>& emplace(initializer_list<U> il, Args&&... args);
`

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7434)

Let VT be decay_t<T>[.](#9.sentence-1)

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7437)

*Constraints*: is_copy_constructible_v<VT> is true andis_constructible_v<VT, initializer_list<U>&, Args...> is true[.](#10.sentence-1)

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7442)

*Preconditions*: VT meets the [*Cpp17CopyConstructible*](utility.arg.requirements#:Cpp17CopyConstructible "16.4.4.2 Template argument requirements [utility.arg.requirements]") requirements[.](#11.sentence-1)

[12](#12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7446)

*Effects*: Calls reset()[.](#12.sentence-1)

Then direct-non-list-initializes the contained value
of type VT with il, std​::​forward<Args>(args)...[.](#12.sentence-2)

[13](#13)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7451)

*Postconditions*: *this contains a value[.](#13.sentence-1)

[14](#14)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7455)

*Returns*: A reference to the new contained value[.](#14.sentence-1)

[15](#15)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7459)

*Throws*: Any exception thrown by the selected constructor of VT[.](#15.sentence-1)

[16](#16)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7463)

*Remarks*: If an exception is thrown during the call to VT's constructor,*this does not contain a value, and any previously contained value
has been destroyed[.](#16.sentence-1)

[ð](#lib:reset,any)

`void reset() noexcept;
`

[17](#17)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7476)

*Effects*: If has_value() is true, destroys the contained value[.](#17.sentence-1)

[18](#18)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7480)

*Postconditions*: has_value() is false[.](#18.sentence-1)

[ð](#lib:swap,any)

`void swap(any& rhs) noexcept;
`

[19](#19)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7492)

*Effects*: Exchanges the states of *this and rhs[.](#19.sentence-1)
