[#BloombergLP-bslstl-Optional_DataImp]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::Optional_DataImp
:relfileprefix: ../../
:mrdocs:

Component‐private buffer managing an optional's contained value.

== Synopsis

Declared in `<bslstl_optional.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class t_TYPE>
struct Optional_DataImp;
----

== Description

This component‐private `struct` manages a `value_type` object in an `Optional_Base` object. This class provides an abstraction for `const` value type. An `Optional_Base` object may contain an object of `const` type. An assignment to such an `Optional_Base` object should not succeed. However, unless the `Optional_Base` object itself is `const`, it should be possible to change the value of the `Optional_Base` object using `emplace`. In order to allow for that, this class manages a non‐const object of `value_type`, but all the accessors return a `const` adjusted reference to the managed object.

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Optional_DataImp/2constructor-02.adoc[`Optional_DataImp`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslstl/Optional_DataImp/emplace-09.adoc[`emplace`] 
| Destroy any contained value and construct a new one in place.
| xref:BloombergLP/bslstl/Optional_DataImp/hasValue.adoc[`hasValue`] 
| Return `true` if this objects has a value, and `false` otherwise.
| xref:BloombergLP/bslstl/Optional_DataImp/reset.adoc[`reset`] 
| Destroy the `value_type` object in `d_buffer`, if any.
| xref:BloombergLP/bslstl/Optional_DataImp/value-0c.adoc[`value`] 
| `value` overloads
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Optional_Data-09.adoc[`Optional_Data<t_TYPE, true>`] 
| Partial specialization for a trivially destructible contained value.
| xref:BloombergLP/bslstl/Optional_Data-0c.adoc[`Optional_Data`] 
| Component‐private storage that destroys a non‐trivial contained value.
|===


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