[#BloombergLP-bslmf-EnableIf-0e4]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmf.adoc[bslmf]::EnableIf
:relfileprefix: ../../
:mrdocs:

Meta‐function that conditionally provides a typedef `type`.

== Synopsis

Declared in `<bslmf_enableif.h>`

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

== Description

This `struct` template implements a meta‐function that provides a `typedef` `type` that is an alias to the (template parameter) `t_TYPE` if the (template parameter) `t_COND` is `true`; otherwise, `type` is not provided. If `t_TYPE` is not specified, it is set to `void`. Note that this generic default template provides `type` for when `t_COND` is `true`; a template specialization is provided (below) that omits `type` for when `t_COND` is `false`.

Also note that although this `struct` is functionally identical to `bsl::enable_if`, the use of `bsl::enable_if` should be preferred.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmf/EnableIf-0e4/type.adoc[`type`] 
| This `typedef` is an alias to the (template parameter) `t_TYPE`.
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmf/EnableIf-0e8.adoc[`EnableIf<false, t_TYPE>`] 
| Partial specialization of `EnableIf` for a false condition.
|===



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