[#BloombergLP-bslstl-Variant_Function-0b-functionImpl]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/Variant_Function-0b.adoc[Variant_Function]::functionImpl
:relfileprefix: ../../../
:mrdocs:

Invoke `visitor` on the active alternative of `variant`.

== Synopsis

Declared in `<bslstl_variant.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
t_RET
functionImpl(
    t_VISITOR&& visitor,
    t_VARIANT&& variant);
----

== Description

This component‐private function invokes the specified `visitor` with the active alternative object of the specified `variant` and implicitly converts the return type to (template parameter) `t_RET`. The pre‐C++17 implementation is limited to invocations of the form `visitor(variant)`. The behavior is undefined unless (template parameter) `t_INDEX` is the index of the active alternative.

== Return Value

result of invoking `visitor`, converted to `t_RET`

== Parameters

[cols="1,4"]
|===
| Name| Description
| *visitor*
| callable to invoke on the active alternative
| *variant*
| variant whose active alternative is visited
|===


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