[#FOLLY_CREATE_MEMBER_INVOKER]
= FOLLY_CREATE_MEMBER_INVOKER
:mrdocs:

* FOLLY_CREATE_MEMBER_INVOKER

== Synopsis

Declared in `<folly/functional/Invoke.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
#define FOLLY_CREATE_MEMBER_INVOKER(classname, membername)

----

== Description

Used to create an invoker type bound to a specific member‐invocable name.

Example:

FOLLY_CREATE_MEMBER_INVOKER(foo_invoker, foo);

The type `foo_invoker` is generated in the current namespace and may be used as follows:

struct CanFoo { int foo(Bar&) { return 1; } int foo(Car&&) noexcept { return 2; } };

using traits = folly::invoke_traits<foo_invoker>;

traits::invoke(CanFoo{}, Car{}) // 2

traits::invoke_result<CanFoo, Bar&> // has member traits::invoke_result_t<CanFoo, Bar&> // int traits::invoke_result<CanFoo, Bar&&> // empty traits::invoke_result_t<CanFoo, Bar&&> // error

traits::is_invocable_v<CanFoo, Bar&> // true traits::is_invocable_v<CanFoo, Bar&&> // false

traits::is_invocable_r_v<int, CanFoo, Bar&> // true traits::is_invocable_r_v<char*, CanFoo, Bar&> // false

traits::is_nothrow_invocable_v<CanFoo, Bar&> // false traits::is_nothrow_invocable_v<CanFoo, Car&&> // true

traits::is_nothrow_invocable_v<int, CanFoo, Bar&> // false traits::is_nothrow_invocable_v<char*, CanFoo, Bar&> // false traits::is_nothrow_invocable_v<int, CanFoo, Car&&> // true traits::is_nothrow_invocable_v<char*, CanFoo, Car&&> // false

== Parameters

[cols="1,4"]
|===
| Name| Description
| *classname*
| the name of the generated invoker type
| *membername*
| the member‐invocable name to bind
|===


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