[#BloombergLP-bslstl-Function_ArgTypes-06]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::Function_ArgTypes
:relfileprefix: ../../
:mrdocs:

Component‐private metafunction providing nested argument typedefs for `bsl::function`.

== Synopsis

Declared in `<bslstl_function.h>`

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

== Description

This component‐private struct template provides the following nested typedefs for `bsl::function` for a specified `PROTOTYPE` which must be a function type: ` argument_type ‐‐ Only if PROTOTYPE takes exactly one argument first_argument_type ‐‐ Only if PROTOTYPE takes exactly two arguments second_argument_type ‐‐ Only if PROTOTYPE takes exactly two arguments ` The C++ Standard requires that `function` define these typedefs for compatibility with one‐ and two‐argument legacy (now deprecated) functor adaptors. `bsl::function` publicly inherits from an instantiation of this template in order to conditionally declare the above nested types. This primary (unspecialized) template provides no typedefs.

== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Function_ArgTypes-05.adoc[`Function_ArgTypes<RET(ARG)>`] 
| `Function_ArgTypes` specialization for single‐argument function prototypes.
| xref:BloombergLP/bslstl/Function_ArgTypes-0d.adoc[`Function_ArgTypes<RET(ARG1, ARG2)>`] 
| `Function_ArgTypes` specialization for two‐argument function prototypes.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Function_Variadic-08.adoc[`Function_Variadic<RET(ARGS...)>`] 
| Component‐private base providing representation and call operator for `bsl::function`.
|===


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