[#BloombergLP-bslmf-ResultType_Fallback-0b]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmf.adoc[bslmf]::ResultType&lowbar;Fallback
:relfileprefix: ../../
:mrdocs:

Metafunction that defines `type` to be the specified `t&lowbar;FALLBACK` type unless `t&lowbar;FALLBACK` is `bslmf&colon;&colon;Nil`&period;

== Synopsis

Declared in `&lt;bslmf&lowbar;resulttype&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;class t&lowbar;FALLBACK&gt;
struct ResultType&lowbar;Fallback;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmf/ResultType_Fallback-0b/type.adoc[`type`] 
| The fallback type, unless `t&lowbar;FALLBACK` is `bslmf&colon;&colon;Nil`&period;
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmf/ResultType_Fallback-07.adoc[`ResultType&lowbar;Fallback&lt;bslmf::Nil&gt;`] 
| Specialization of `ResultType&lowbar;Fallback` that does not define `type` if `bslmf&colon;&colon;Nil` is specified as the fallback parameter&period;
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmf/ResultType_BdeIdiom-0d.adoc[`ResultType&lowbar;BdeIdiom`] 
| Metafunction to detect the BDE `ResultType` idiom&period;
|===


[.small]#Created with https://www.mrdocs.com[MrDocs]#
