[#BloombergLP-bdlb-Variant_RawVisitorHelper]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlb.adoc[bdlb]::Variant_RawVisitorHelper
:relfileprefix: ../../
:mrdocs:

This `struct` provides a helper for implementing `Variant::applyRaw` that enables `applyRaw` to support visitor functors that do not provide an overload for `operator()(bslmf::Nil)`. Objects of this type are constructed using a functor of (template parameter) type `VISITOR`, whose `operator()` returns the (template parameter) type `RESULT_TYPE`. A `Variant_RawVisitorHelper` wraps a functor of type `VISITOR` and provides an implementation of `operator()(bslmf::Nil)` that performs a `BSLS_ASSERT_OPT(false)`. Note that this overload is needed to enable compilation (specifically, to instantiate `doApply` and `doApplyR`), but is never invoked by any code path at runtime.

== Synopsis

Declared in `<bdlb_variant.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class RESULT_TYPE,
    class VISITOR>
class Variant_RawVisitorHelper;
----

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlb/Variant_RawVisitorHelper/2constructor.adoc[`Variant_RawVisitorHelper`]         [.small]#[constructor]#
| Create a `RawVisitorHelper` functor that delegates to the specified `visitor`.
| xref:BloombergLP/bdlb/Variant_RawVisitorHelper/operator_call-0b.adoc[`operator()`] 
| Function call operators
|===



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