[#beman-optional-optional-06-2constructor-07d]
= xref:beman.adoc[beman]::xref:beman/optional.adoc[optional]::xref:beman/optional/optional-06.adoc[optional<T&>]::optional
:relfileprefix: ../../../
:mrdocs:

Constructs an optional from another optional of type U

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class U>
requires (std::is_constructible_v<T&, const U&> && !std::is_same_v<std::remove_cv_t<T>, optional<U>> &&
                 !std::is_same_v<T&, U> && detail::reference_constructs_from_temporary_v<T&, const U&>)
constexpr
optional(xref:beman/optional/optional-03.adoc[optional<U>] const& rhs) = delete;
----

== Description

Constructs the stored value from the rhs if it has a value, otherwise constructs an empty optional. If `T&` can be constructed from a temporary, this constructor is deleted to prevent binding a temporary to a reference.

== Template Parameters

[cols=2]
|===
| Name
| Description
| *U*
| 
|===

== Parameters

[cols=2]
|===
| Name
| Description
| *rhs*
| 
|===


[.small]#Created with https://www.mrdocs.com[MrDocs]#