[#BloombergLP-bdlat_ChoiceFunctions-IsChoice-04]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlat_ChoiceFunctions.adoc[bdlat&lowbar;ChoiceFunctions]::IsChoice
:relfileprefix: ../../
:mrdocs:

This `struct` should be specialized for third&hyphen;party types that need to expose &quot;choice&quot; behavior&period; See the component&hyphen;level documentation for further information&period;

== Synopsis

Declared in `&lt;bdlat&lowbar;choicefunctions&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;class TYPE&gt;
struct IsChoice
    : xref:bsl/integral_constant-02.adoc[bsl::integral&lowbar;constant&lt;bool, bslalg&colon;&colon;HasTrait&lt;TYPE, bdlat&lowbar;TypeTraitBasicChoice&gt;&colon;&colon;value&gt;]
----

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:bsl/integral_constant-02.adoc[bsl::integral&lowbar;constant&lt;bool, bslalg&colon;&colon;HasTrait&lt;TYPE, bdlat&lowbar;TypeTraitBasicChoice&gt;&colon;&colon;value&gt;]`
| Metafunction representing a compile&hyphen;time constant of the specified (template parameter) `t&lowbar;TYPE` with the specified (template parameter) `t&lowbar;VALUE`&period;
|===

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/integral_constant-02/type.adoc[`type`] 
| Alias for this `integral&lowbar;constant` specialization&period;
| xref:bsl/integral_constant-02/value_type.adoc[`value&lowbar;type`] 
| 
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/integral_constant-02/operator_call.adoc[`operator()`] 
| Return a copy of the template argument `t&lowbar;VALUE`&period;
| xref:bsl/integral_constant-02/2conversion.adoc[`operator value&lowbar;type`] 
| 
|===


== Static Data Members

[cols="1"]
|===
| Name
| xref:bsl/integral_constant-02/value.adoc[`value`] 
|===


== Specializations

[cols="1"]
|===
| Name
| xref:BloombergLP/bdlat_ChoiceFunctions/IsChoice-03.adoc[`IsChoice&lt;bdlar::ChoiceConstRef&gt;`] 
| xref:BloombergLP/bdlat_ChoiceFunctions/IsChoice-05.adoc[`IsChoice&lt;bdlar::ChoiceRef&gt;`] 
|===



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