[#BloombergLP-bdlf-Bind_FuncTraitsImp-05]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlf.adoc[bdlf]::Bind_FuncTraitsImp
:relfileprefix: ../../
:mrdocs:

This `struct` provides a mechanism for inferring various traits of the function object type `t_FUNC`. The return type is given by `t_RET` unless it is `bslmf::Nil` in which case it is inferred from `t_FUNC`. The last three parameters `IS_FUNCTION`, `IS_FUNCTION_POINTER` and `IS_MEMBER_FUNCTION_POINTER` specify whether `t_FUNC` is a free function type (either a reference‐to‐function or plain function type), a pointer to function type, or a pointer to member function type, respectively.

== Synopsis

Declared in `<bdlf_bind.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class t_RET,
    class t_FUNC,
    int IS_FUNCTION,
    int IS_FUNCTION_POINTER,
    int IS_MEMBER_FUNCTION_POINTER>
struct Bind_FuncTraitsImp;
----

== Description

Only specializations of this class should be used (given below). All specializations define the types and enumerations documented in the `Bind_FuncTraits` below.

== Specializations

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-088.adoc[`Bind_FuncTraitsImp<bslmf::Nil, t_FUNC, 0, 0, 0>`] 
| Function traits for function objects that are passed by value without explicit result type specification. The result type is determined by either `typename t_FUNC::result_type` or `typename t_FUNC::ResultType`, with the former taking precedence if both are defined.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-0a.adoc[`Bind_FuncTraitsImp<bslmf::Nil, t_FUNC, 0, 0, 1>`] 
| Function traits for member function pointers. The result type is determined from the function pointer traits.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-086.adoc[`Bind_FuncTraitsImp<bslmf::Nil, t_FUNC, 0, 1, 0>`] 
| Function traits for non‐member function pointers. The result type is determined from the function pointer traits.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-048.adoc[`Bind_FuncTraitsImp<bslmf::Nil, t_FUNC, 1, 0, 0>`] 
| Function traits for non‐member function types (references or not, but not pointers to function). The result type is determined from the function pointer traits.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-0f2.adoc[`Bind_FuncTraitsImp<bslmf::Nil, bsl::function<PROTO>, 0, 0, 0>`] 
| Function traits for bsl::function objects that are passed by value. The result type is determined by `bsl::function<PROTO>::result_type`.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-0b.adoc[`Bind_FuncTraitsImp<bslmf::Nil, t_FUNC*, 0, 0, 0>`] 
| Function traits for objects passed by pointer with no explicit return type. The object is assumed to have a `result_type` or `ResultType` type definition, with the former taking precedence if both are defined.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-0e.adoc[`Bind_FuncTraitsImp<bslmf::Nil, bsl::function<PROTO>*, 0, 0, 0>`] 
| Function traits for objects passed by pointer with no explicit return type. The object is assumed to have a `ResultType` type definition.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-07.adoc[`Bind_FuncTraitsImp<t_RET, t_FUNC, 0, 0, 0>`] 
| Function traits for function objects that are passed by value with explicit return type specification.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-00.adoc[`Bind_FuncTraitsImp<t_RET, t_FUNC, 0, 0, 1>`] 
| Function traits for member function pointers, with explicit return type specification.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-0fc.adoc[`Bind_FuncTraitsImp<t_RET, t_FUNC, 0, 1, 0>`] 
| Function traits for non‐member function pointers, with explicit return type specification.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-047.adoc[`Bind_FuncTraitsImp<t_RET, t_FUNC, 1, 0, 0>`] 
| Function traits for non‐member function types (references or not, but not pointers to function), with explicit return type specification.
| xref:BloombergLP/bdlf/Bind_FuncTraitsImp-09.adoc[`Bind_FuncTraitsImp<t_RET, t_FUNC*, 0, 0, 0>`] 
| Function traits for objects passed by pointer with explicit return type.
|===


== Derived Classes

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlf/Bind_FuncTraits.adoc[`Bind_FuncTraits`] 
| This `struct` provides various traits of the functor type `t_FUNC` documented below. If `t_RET` is `bslmf::Nil`, then the return type is inferred by using either `bslmf::FunctionPointerTraits`, `bslmf::MemberFunctionPointerTraits`, or `typename t_FUNC::result_type` as appropriate. ` // ENUMERATIONS enum { k_IS_EXPLICIT // An invocable object is explicit if ... // (see 'Bind_ImplExplicit')
|===


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