[#BloombergLP-bslstl-Function_Variadic-08]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/Function_Variadic-0e.adoc[Function_Variadic]<RET(ARGS...)>
:relfileprefix: ../../
:mrdocs:

This component‐private class template contains the physical representation and provides the variadic interfaces for `bsl::function` (see class and component documentation for `bsl::function`). `bsl::function` publicly inherits from an instantiation of this template. This implementation class exists to 1) minimize the amount of variadic template expansion required in C++03 using the `sim_cpp11_features.pl` utility and 2) work around issues with the Sun CC compiler, which has trouble with argument type deduction when a template argument has a partial specialization (as `Function_Variadic` does). `bsl::function` does not have a partial specialization and delegates to the `Function_Variadic` base class only those parts of the interface and implementation that depend on decomposing the function prototype into a return type and variadic list of argument types.

== Synopsis

Declared in `<bslstl_function.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class RET,
    class... ARGS>
class xref:BloombergLP/bslstl/Function_Variadic-0e.adoc[Function_Variadic]<RET(ARGS...)>
    : public xref:BloombergLP/bslstl/Function_ArgTypes-06.adoc[Function_ArgTypes<RET(ARGS...)>]
----

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bslstl/Function_ArgTypes-06.adoc[Function_ArgTypes<RET(ARGS...)>]`
| 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.
|===

== Type Aliases

[cols="1"]
|===
| Name
| xref:BloombergLP/bslstl/Function_Variadic-08/allocator_type.adoc[`allocator_type`] 
| xref:BloombergLP/bslstl/Function_Variadic-08/result_type.adoc[`result_type`] 
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslstl/Function_Variadic-08/2constructor.adoc[`Function_Variadic`]         [.small]#[constructor]#
| Create an empty object. Use the specified `allocator` (e.g., the address of a `bslma::Allocator`) to supply memory.
| xref:BloombergLP/bslstl/Function_Variadic-08/operator_call.adoc[`operator()`] 
| If this object is empty, throw `bsl::bad_function_call`; otherwise invoke the target object with the specified `args...` and return the result (after conversion to `RET`). Note that, even though it is declared `const`, this call operator can mutate the target object and is thus considered a manipulator rather than an accessor.
|===


== Protected Data Members

[cols="1"]
|===
| Name
| xref:BloombergLP/bslstl/Function_Variadic-08/d_rep.adoc[`d_rep`] 
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:bsl/function-0a.adoc[bsl::function]`
| Forward declaration.
|===


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