[#beman-optional-optional-03-2constructor-026]
= xref:beman.adoc[beman]::xref:beman/optional.adoc[optional]::xref:beman/optional/optional-03.adoc[optional]::optional
:relfileprefix: ../../../
:mrdocs:

Constructors

== Synopses

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

Default constructs an empty optional.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-066.adoc[optional]() noexcept;
----

[.small]#xref:beman/optional/optional-03/2constructor-066.adoc[_» more..._]#

Copy constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-06c.adoc[optional](xref:beman/optional/optional-03.adoc[optional] const& other)
requires std::is_copy_constructible_v<T> && std::is_trivially_copy_constructible_v<T> = default;
----

[.small]#xref:beman/optional/optional-03/2constructor-06c.adoc[_» more..._]#

Copy constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-0c.adoc[optional](xref:beman/optional/optional-03.adoc[optional] const& rhs)
requires std::is_copy_constructible_v<T> && (!std::is_trivially_copy_constructible_v<T>);
----

[.small]#xref:beman/optional/optional-03/2constructor-0c.adoc[_» more..._]#

Constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class U>
constexpr
explicit(!std::is_convertible_v<U, T>)
xref:beman/optional/optional-03/2constructor-04a.adoc[optional](xref:beman/optional/optional-03.adoc[optional<U>] const& rhs)
requires (detail::enable_from_other<T, U, const U&>);
----

[.small]#xref:beman/optional/optional-03/2constructor-04a.adoc[_» more..._]#

Move constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-05.adoc[optional](xref:beman/optional/optional-03.adoc[optional]&& other)
requires std::is_move_constructible_v<T> && std::is_trivially_move_constructible_v<T> = default;
----

[.small]#xref:beman/optional/optional-03/2constructor-05.adoc[_» more..._]#

Move constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-0b.adoc[optional](xref:beman/optional/optional-03.adoc[optional]&& rhs) noexcept(std::is_nothrow_move_constructible_v<T>)
requires std::is_move_constructible_v<T> && (!std::is_trivially_move_constructible_v<T>);
----

[.small]#xref:beman/optional/optional-03/2constructor-0b.adoc[_» more..._]#

Constructs the value from `rhs` if it has one.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class U>
constexpr
explicit(!std::is_convertible_v<U, T>)
xref:beman/optional/optional-03/2constructor-06e.adoc[optional](xref:beman/optional/optional-03.adoc[optional<U>]&& rhs)
requires (detail::enable_from_other<T, U, U &&>);
----

[.small]#xref:beman/optional/optional-03/2constructor-06e.adoc[_» more..._]#

Constructs an empty optional.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:beman/optional/optional-03/2constructor-043.adoc[optional](xref:beman/optional/nullopt_t.adoc[nullopt_t] value) noexcept;
----

[.small]#xref:beman/optional/optional-03/2constructor-043.adoc[_» more..._]#

Constructs the value from `u,` forwarding it if necessary.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class U = T>
constexpr
explicit(!std::is_convertible_v<U, T>)
xref:beman/optional/optional-03/2constructor-00.adoc[optional](U&& u)
requires detail::enable_forward_value<T, U>;
----

[.small]#xref:beman/optional/optional-03/2constructor-00.adoc[_» more..._]#

Constructs the value in‐place using the given arguments.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class... Args>
constexpr
explicit
xref:beman/optional/optional-03/2constructor-02a.adoc[optional](
    xref:beman/optional/in_place_t.adoc[in_place_t],
    Args...&&... args)
requires std::is_constructible_v<T, Args...>;
----

[.small]#xref:beman/optional/optional-03/2constructor-02a.adoc[_» more..._]#

Constructs the value in‐place using the given arguments.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class U,
    class... Args>
constexpr
explicit
xref:beman/optional/optional-03/2constructor-07.adoc[optional](
    xref:beman/optional/in_place_t.adoc[in_place_t],
    std::initializer_list<U> il,
    Args...&&... args)
requires std::is_constructible_v<T, std::initializer_list<U>&, Args&&...>;
----

[.small]#xref:beman/optional/optional-03/2constructor-07.adoc[_» more..._]#


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