[#BloombergLP-bdlb-NullableValue_DerivedFromOptional]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlb.adoc[bdlb]::NullableValue&lowbar;DerivedFromOptional
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This component&hyphen;private concept models whether a type is derived from one of `std&colon;&colon;optional`, or `bsl&colon;&colon;optional`&period; Note that this concept is always satisfied for `bdlb&colon;&colon;NullableValue` as it is derived from `bsl&colon;&colon;optional`&period;

== Synopsis

Declared in `&lt;bdlb&lowbar;nullablevalue&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;class t&lowbar;TYPE&gt;
concept NullableValue&lowbar;DerivedFromOptional = NullableValue&lowbar;DerivedFromBslOptional&lt;t&lowbar;TYPE&gt;   &verbar;&verbar;
    NullableValue&lowbar;DerivedFromStdOptional&lt;t&lowbar;TYPE&gt;;
----


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