[#BloombergLP-bdlar-NullableValueRef]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlar.adoc[bdlar]::NullableValueRef
:relfileprefix: ../../
:mrdocs:

Type‐erased non‐const reference to an object in the `bdlat` nullable‐value type category.

== Synopsis

Declared in `<bdlar_nullablevalueref.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class NullableValueRef;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlar/NullableValueRef/CategoryTag.adoc[`CategoryTag`] 
| Tag type indicating the nullable‐value type category.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlar/NullableValueRef/2constructor-0f.adoc[`NullableValueRef`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bdlar/NullableValueRef/accessValue.adoc[`accessValue`] 
| Invoke the specified `accessor` on the referred non‐null value. The supplied `accessor` must be a callable type that can be called as if it had the following signature: ` int accessor(const VALUE& refOrValue); ` Return the value from the invocation of `accessor`. The behavior is undefined if the referred object is null.
| xref:BloombergLP/bdlar/NullableValueRef/isNull.adoc[`isNull`] 
| Return `true` if the referred object contains a null value, and `false` otherwise.
| xref:BloombergLP/bdlar/NullableValueRef/makeValue.adoc[`makeValue`] 
| Assign to the referred object the default value for the contained type.
| xref:BloombergLP/bdlar/NullableValueRef/manipulateValue.adoc[`manipulateValue`] 
| Invoke the specified `manipulator` on the referred non‐null value. The supplied `manipulator` must be a callable type that can be called as if it had the following signature: ` int manipulator(VALUE *refOrValue); ` Return the value from the invocation of `manipulator`. The behavior is undefined if the referred object is null.
| xref:BloombergLP/bdlar/NullableValueRef/objectAddress.adoc[`objectAddress`] 
| Return a pointer to the wrapped object.
| xref:BloombergLP/bdlar/NullableValueRef/reset.adoc[`reset`] 
| Reset the referred object to the default value.
| xref:BloombergLP/bdlar/NullableValueRef/valueCategory.adoc[`valueCategory`] 
| Return the value type category.
| xref:BloombergLP/bdlar/NullableValueRef/vtable.adoc[`vtable`] 
| Return a pointer to the vtable.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlar/bdlat_nullableValueAccessValue-06.adoc[`bdlat_nullableValueAccessValue`]
| Invoke `accessor` on the non‐null value held by `ref`.
| xref:BloombergLP/bdlar/bdlat_nullableValueIsNull-04.adoc[`bdlat_nullableValueIsNull`]
| Return `true` if the specified `ref` contains a null value, and `false` otherwise.
| xref:BloombergLP/bdlar/bdlat_nullableValueMakeValue.adoc[`bdlat_nullableValueMakeValue`]
| Create a value in the specified `ref` if it is currently null.
| xref:BloombergLP/bdlar/bdlat_nullableValueManipulateValue.adoc[`bdlat_nullableValueManipulateValue`]
| Invoke the specified `manipulator` on the non‐null value held by the specified `ref`. Return the value from the invocation of `manipulator`.
| xref:BloombergLP/bdlar/bdlat_valueTypeReset-0c.adoc[`bdlat_valueTypeReset`]
| Reset the specified `ref` to its default‐constructed state.
|===


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