[#beman-optional-optional-06-emplace]
= xref:beman.adoc[beman]::xref:beman/optional.adoc[optional]::xref:beman/optional/optional-06.adoc[optional<T&>]::emplace
:relfileprefix: ../../../
:mrdocs:

Emplaces a new value in the optional, destroying the current one if the optional is engaged.

== Synopsis

Declared in `<beman/optional/optional.hpp>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class U>
requires (std::is_constructible_v<T&, U> && !detail::reference_constructs_from_temporary_v<T&, U>)
constexpr
T&
emplace(U&& u) noexcept(std::is_nothrow_constructible_v<T &, U>);
----

== Description

Constructs the contained value from `u` if it is convertible to `T&`.

== Return Value

T&

== Template Parameters

[cols="1,4"]
|===
|Name|Description

| *U*
| The type of the value to emplace.
|===

== Parameters

[cols="1,4"]
|===
|Name|Description

| *u*
| The value to emplace.
|===


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