[#bsl-visit-0d1]
= xref:bsl.adoc[bsl]::visit
:relfileprefix: ../
:mrdocs:

Return the result of invoking `visitor` with the active alternative of `variant`.

== Synopsis

Declared in `<bslstl_variant.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_VISITOR,
    class t_VARIANT>
bsl::invoke_result<t_VISITOR&&, decltype(get<0>(BloombergLP::bslstl::Variant_ImpUtil::
                    asVariant(std::forward<t_VARIANT>(variant))))>::type
visit(
    t_VISITOR&& visitor,
    t_VARIANT&& variant);
----

== Description

Return the result of invoking the specified `visitor` with the currently active alternative of the specified `variant`. If `variant` does not hold a value, throw an exception of type `bsl::bad_variant_access`. For each alternative, invocation of the visitor with that alternative shall be of the same type and value category. This function differs from the standard in the following ways: * only one variant is supported * constexpr is not implemented * before C++17, only `t_VISITOR(ALTERNATIVE)` form of visitation is supported; cases where the visitor is a pointer to member are not supported.

== Return Value

result of invoking `visitor` on the active alternative

== 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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