[#bsl-conditional-0c]
= xref:bsl.adoc[bsl]::conditional
:relfileprefix: ../
:mrdocs:

This `struct` template implements the `conditional` meta‐function defined in the C++ standard [meta.trans.other], providing an alias, `type`, that returns the result. If the (template parameter) value `t_COND` is `true`, then `type` has the same type as the (template parameter) type `t_TRUE_TYPE`; otherwise, `type` has the same type as the (template parameter) type `t_FALSE_TYPE`. Note that this generic default template defines `type` to be an alias to `t_TRUE_TYPE` for when `t_COND` is `true`. A template specialization is provided (below) handles the case for when `t_COND` is `false`.

== Synopsis

Declared in `<bslmf_conditional.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    bool t_COND,
    class t_TRUE_TYPE,
    class t_FALSE_TYPE>
struct conditional;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/conditional-0c/type.adoc[`type`] 
| This `typedef` is an alias to the (template parameter) type `t_TRUE_TYPE`.
|===


== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:bsl/conditional-0b.adoc[`conditional<false, PackedIntArrayImp<PackedIntArrayImp_Unsigned>, PackedIntArrayImp<PackedIntArrayImp_Signed>>`] 
| This partial specialization of `bsl::conditional`, for when the (template parameter) value `t_COND` is `false`, provides a `typedef` `type` that is an alias to the (template parameter) type `t_FALSE_TYPE`.
| xref:bsl/conditional-0f.adoc[`conditional<false, t_TRUE_TYPE, t_FALSE_TYPE>`] 
| This partial specialization of `bsl::conditional`, for when the (template parameter) value `t_COND` is `false`, provides a `typedef` `type` that is an alias to the (template parameter) type `t_FALSE_TYPE`.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslma/ManagedPtr_FactoryDeleterType.adoc[`ManagedPtr_FactoryDeleterType`] 
| This metafunction class‐template provides a means to compute the preferred deleter function for a factory class for those methods of `ManagedPtr` that supply only a factory, and no additional deleter function. The intent is to use a common deleter function for all allocators that implement the `bslma::Allocator` protocol, rather than create a special deleter function based on the complete type of each allocator, each doing the same thing (invoking the virtual function `deleteObject`).
|===


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