[optional.specalg]

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

## 22.5 Optional objects [[optional]](optional#specalg)

### 22.5.10 Specialized algorithms [optional.specalg]

[ð](#lib:swap,optional)

`template<class T>
  constexpr void swap(optional<T>& x, optional<T>& y) noexcept(noexcept(x.swap(y)));
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5456)

*Constraints*: is_reference_v<T> || (is_move_constructible_v<T> && is_swappable_v<T>) is true[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5463)

*Effects*: Calls x.swap(y)[.](#2.sentence-1)

[ð](#lib:make_optional)

`template<class T> constexpr optional<decay_t<T>> make_optional(T&& v);
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5474)

*Constraints*: The call to make_optional does not use
an explicit [*template-argument-list*](temp.names#nt:template-argument-list "13.3 Names of template specializations [temp.names]") that
begins with a type [*template-argument*](temp.names#nt:template-argument "13.3 Names of template specializations [temp.names]")[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5480)

*Returns*: optional<decay_t<T>>(std​::​forward<T>(v))[.](#4.sentence-1)

[ð](#lib:make_optional_)

`template<class T, class...Args>
  constexpr optional<T> make_optional(Args&&... args);
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5492)

*Effects*: Equivalent to: return optional<T>(in_place, std​::​forward<Args>(args)...);

[ð](#lib:make_optional__)

`template<class T, class U, class... Args>
  constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args);
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5504)

*Effects*: Equivalent to: return optional<T>(in_place, il, std​::​forward<Args>(args)...);
