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

This class is a wrapper for either a `bsl::optional` or `NullableAllocatedValue`, and provides non‐modifiable access to the wrapped object.

== Synopsis

Declared in `<bdlb_nullablevalueref.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class TYPE>
class ConstNullableValueRef;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlb/ConstNullableValueRef/value_type.adoc[`value_type`] 
| `value_type` is an alias for the template parameter `TYPE`, and represents the type of the object managed by the wrapped nullable object.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlb/ConstNullableValueRef/2constructor-05.adoc[`ConstNullableValueRef`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bdlb/ConstNullableValueRef/addressOr.adoc[`addressOr`] 
| Return the address of the value, or `address` if null.
| xref:BloombergLP/bdlb/ConstNullableValueRef/has_value.adoc[`has_value`] 
| Return `true` if the target contains a value, and `false` otherwise.
| xref:BloombergLP/bdlb/ConstNullableValueRef/isNull.adoc[`isNull`] 
| Return whether the target does not contain a value.
| xref:BloombergLP/bdlb/ConstNullableValueRef/operator_star.adoc[`operator*`] 
| Return a reference providing non‐modifiable access to the underlying `TYPE` object. The behavior is undefined if the target has no value.
| xref:BloombergLP/bdlb/ConstNullableValueRef/operator_ptr.adoc[`operator‐>`] 
| Return a pointer providing non‐modifiable access to the underlying `TYPE` object. The behavior is undefined if the target has no value.
| xref:BloombergLP/bdlb/ConstNullableValueRef/value.adoc[`value`] 
| Return a non‐modifiable reference to the underlying value.
| xref:BloombergLP/bdlb/ConstNullableValueRef/valueOr.adoc[`valueOr`] 
| Return the underlying value, or `otherValue` if null.
| xref:BloombergLP/bdlb/ConstNullableValueRef/valueOrNull.adoc[`valueOrNull`] 
| Return an address providing non‐modifiable access to the underlying object of a (template parameter) `TYPE` if this object is non‐null, and 0 otherwise.
| xref:BloombergLP/bdlb/ConstNullableValueRef/value_or.adoc[`value_or`] 
| Return the underlying value, or `default_value` if null.
| xref:BloombergLP/bdlb/ConstNullableValueRef/2conversion.adoc[`operator bool`] 
| Return `true` if the target holds a value, and `false` otherwise.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlb/operator_not_eq-001.adoc[`operator!=`]
| Return whether `lhs` and `rhs` do not have the same value.
| xref:BloombergLP/bdlb/operator_not_eq-051.adoc[`operator!=`]
| Return whether `lhs` and `rhs` do not have the same value.
| xref:BloombergLP/bdlb/operator_not_eq-0c0.adoc[`operator!=`]
| Return whether `lhs` is not null.
| xref:BloombergLP/bdlb/operator_not_eq-0eb.adoc[`operator!=`]
| Return whether `lhs` and `rhs` do not have the same value.
| xref:BloombergLP/bdlb/operator_lt-033.adoc[`operator<`]
| Return whether `lhs` is ordered before `rhs`.
| xref:BloombergLP/bdlb/operator_lt-054c.adoc[`operator<`]
| Return `false`; nullopt never orders after a nullable reference.
| xref:BloombergLP/bdlb/operator_lt-0f9.adoc[`operator<`]
| Return whether `lhs` is ordered before `rhs`.
| xref:BloombergLP/bdlb/operator_lt-0fe.adoc[`operator<`]
| Return whether `lhs` is ordered before `rhs`.
| xref:BloombergLP/bdlb/operator_le-054.adoc[`operator<=`]
| Return whether `lhs` is ordered before `rhs` or they are equal.
| xref:BloombergLP/bdlb/operator_le-0b.adoc[`operator<=`]
| Return whether `lhs` is ordered before `rhs` or they are equal.
| xref:BloombergLP/bdlb/operator_le-0d.adoc[`operator<=`]
| Return whether `lhs` is null.
| xref:BloombergLP/bdlb/operator_le-0f6.adoc[`operator<=`]
| Return whether `lhs` is ordered before `rhs` or they are equal.
| xref:BloombergLP/bdlb/operator_eq-003.adoc[`operator==`]
| Return whether `lhs` and `rhs` have the same value.
| xref:BloombergLP/bdlb/operator_eq-01c.adoc[`operator==`]
| Return whether `lhs` and `rhs` have the same value.
| xref:BloombergLP/bdlb/operator_eq-03cc.adoc[`operator==`]
| Return whether `lhs` is null.
| xref:BloombergLP/bdlb/operator_eq-04f.adoc[`operator==`]
| Return whether `lhs` and `rhs` have the same value.
| xref:BloombergLP/bdlb/operator_gt-02.adoc[`operator>`]
| Return whether `lhs` is not null.
| xref:BloombergLP/bdlb/operator_gt-04f.adoc[`operator>`]
| Return whether `lhs` is ordered after `rhs`.
| xref:BloombergLP/bdlb/operator_gt-098.adoc[`operator>`]
| Return whether `lhs` is ordered after `rhs`.
| xref:BloombergLP/bdlb/operator_gt-0b0.adoc[`operator>`]
| Return whether `lhs` is ordered after `rhs`.
| xref:BloombergLP/bdlb/operator_ge-008.adoc[`operator>=`]
| Return `true`.
| xref:BloombergLP/bdlb/operator_ge-035.adoc[`operator>=`]
| Return whether `lhs` is ordered after `rhs` or they are equal.
| xref:BloombergLP/bdlb/operator_ge-09f9.adoc[`operator>=`]
| Return whether `lhs` is ordered after `rhs` or they are equal.
| xref:BloombergLP/bdlb/operator_ge-0a.adoc[`operator>=`]
| Return whether `lhs` is ordered after `rhs` or they are equal.
|===


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