[#BloombergLP-bslstl-Variant_HasUniqueType-0d]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::Variant_HasUniqueType
:relfileprefix: ../../
:mrdocs:

Determine whether `t_TYPE` occurs exactly once in `t_VARIANT`.

== Synopsis

Declared in `<bslstl_variant.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_TYPE,
    class t_VARIANT>
struct Variant_HasUniqueType;
----

== Description

This component‐private metafunction derives from `bsl::true_type` if (template parameter) `t_TYPE` occurs exactly once as an alternative of (template parameter) `t_VARIANT`, and `bsl::false_type` otherwise.

An alternative must have the same cv‐qualification as `t_TYPE` in order to be counted. The primary template (used when `t_VARIANT` is not a `bsl::variant`) is not defined.

== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Variant_HasUniqueType-02.adoc[`Variant_HasUniqueType<t_TYPE, bsl::variant<t_HEAD, t_TAIL...>>`] 
| Determine whether `t_TYPE` occurs exactly once in a `bsl::variant`.
|===



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