[#bsl-optional-072-operator_assign-01]
= xref:bsl.adoc[bsl]::xref:bsl/optional-072.adoc[optional]::operator=
:relfileprefix: ../../
:mrdocs:

Assignment operators

== Synopses

Declared in `<bslstl_optional.h>`

Assign to this object the value of the specified `rhs` object, and return a non‐`const` reference to this object.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:BloombergLP/bslstl/Optional_Base-05.adoc[Optional_Base<t_TYPE, t_USES_BSLMA_ALLOC>]&
xref:BloombergLP/bslstl/Optional_Base-05/operator_assign-05.adoc[operator=](xref:BloombergLP/bslstl/Optional_Base-05.adoc[Optional_Base] const& rhs);
----

[.small]#xref:BloombergLP/bslstl/Optional_Base-05/operator_assign-05.adoc[_» more..._]#

Disengage this object if the specified `rhs` object is disengaged, and assign to this object the value of `rhs.value()` (of `t_ANY_TYPE`) converted to `t_TYPE` otherwise. Return a reference providing modifiable access to this object. Note that this method does not participate in overload resolution unless `t_TYPE` and `t_ANY_TYPE` are compatible. This assignment operator can be called in constant expressions only when neither `t_TYPE` nor `t_ANY_TYPE` is allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_ANY_TYPE>
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-08.adoc[operator=](xref:bsl/optional-072.adoc[optional<t_ANY_TYPE>] const& rhs);
----

[.small]#xref:bsl/optional-072/operator_assign-08.adoc[_» more..._]#

Reset this object to be disengaged and return a reference providing modifiable access to this object. This assignment operator can be called in constant expressions only when `t_TYPE` is not allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-09.adoc[operator=](xref:bsl/nullopt_t.adoc[bsl::nullopt_t]) noexcept;
----

[.small]#xref:bsl/optional-072/operator_assign-09.adoc[_» more..._]#

Assign to this object the value of the specified `rhs` object, and return a non‐`const` reference to this object. The allocators of this object and `rhs` both remain unchanged. The contents of `rhs` are either move‐constructed into or move‐assigned to this object. `rhs` is left in a valid but unspecified state.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:BloombergLP/bslstl/Optional_Base-05.adoc[Optional_Base<t_TYPE, t_USES_BSLMA_ALLOC>]&
xref:BloombergLP/bslstl/Optional_Base-05/operator_assign-08.adoc[operator=](xref:BloombergLP/bslmf/MovableRef.adoc[BloombergLP::bslmf::MovableRef<Optional_Base>] rhs);
----

[.small]#xref:BloombergLP/bslstl/Optional_Base-05/operator_assign-08.adoc[_» more..._]#

Disengage this object if the specified `rhs` object is disengaged, and move assign to this object the value of `rhs.value()` (of `t_ANY_TYPE`) converted to `t_TYPE` otherwise. Return a reference providing modifiable access to this object. Note that this method does not participate in overload resolution unless `t_TYPE` and `t_ANY_TYPE` are compatible. This assignment operator can be called in constant expressions only when neither `t_TYPE` nor `t_ANY_TYPE` is allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_ANY_TYPE>
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-0f.adoc[operator=](xref:BloombergLP/bslmf/MovableRef_Deduced.adoc[BloombergLP::bslmf::MovableRef_Deduced<optional<t_ANY_TYPE>>] rhs);
----

[.small]#xref:bsl/optional-072/operator_assign-0f.adoc[_» more..._]#

Disengage this object if the specified `rhs` object is disengaged, and assign to this object the value of `rhs.value()` (of `t_ANY_TYPE`) converted to `t_TYPE` otherwise. Return a reference providing modifiable access to this object. Note that this method does not participate in overload resolution unless `t_TYPE` and `t_ANY_TYPE` are compatible. This assignment operator can be called in constant expressions only when `t_TYPE` is not allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_ANY_TYPE = t_TYPE>
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-06.adoc[operator=](std::optional<t_ANY_TYPE> const& rhs);
----

[.small]#xref:bsl/optional-072/operator_assign-06.adoc[_» more..._]#

Assign to this object the value of the specified `rhs` object converted to `t_TYPE`, and return a reference providing modifiable access to this object. Note that this method may invoke assignment from `rhs`, or construction from `rhs`, depending on whether this object is engaged. This assignment operator does not participate in overload resolution if `t_ANY_TYPE` is possibly cv‐qualified `bsl::optional<t_TYPE>`. Also note that an assignment of the form `o = {};`, where `o` is of type `optional`, will always assign to `o` the empty state, and never call this overload (see implementation notes). This assignment operator can be called in constant expressions only when `t_TYPE` is not allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_ANY_TYPE = t_TYPE>
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-0d.adoc[operator=](t_ANY_TYPE&& rhs);
----

[.small]#xref:bsl/optional-072/operator_assign-0d.adoc[_» more..._]#

Disengage this object if the specified `rhs` object is disengaged, and move assign to this object the value of `rhs.value()` (of `t_ANY_TYPE`) converted to `t_TYPE` otherwise. Return a reference providing modifiable access to this object. Note that this method does not participate in overload resolution unless `t_TYPE` and `t_ANY_TYPE` are compatible. This assignment operator can be called in constant expressions only when `t_TYPE` is not allocator‐aware.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_ANY_TYPE = t_TYPE>
constexpr
xref:bsl/optional-072.adoc[optional<t_TYPE>]&
xref:bsl/optional-072/operator_assign-0e.adoc[operator=](std::optional<t_ANY_TYPE>&& rhs);
----

[.small]#xref:bsl/optional-072/operator_assign-0e.adoc[_» more..._]#


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