[#beman-optional-operator_3way-09]
= xref:beman.adoc[beman]::xref:beman/optional.adoc[optional]::operator<=>
:relfileprefix: ../../
:mrdocs:

Three‐way comparison of two optionals.

== Synopsis

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

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    typename T,
    std::three_way_comparable_with<T> U>
constexpr
std::compare_three_way_result_t<T, U>
operator<=>(
    xref:beman/optional/optional-03.adoc[optional<T>] const& lhs,
    xref:beman/optional/optional-03.adoc[optional<U>] const& rhs);
----

== Return Value

The comparison category; a disengaged optional orders before any engaged one.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *lhs*
| The left‐hand optional.
| *rhs*
| The right‐hand optional.
|===


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