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std::function_ref

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< cpp‎ | utility‎ | functional

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(until C++20*)

std::function_ref

Member functions

function_ref::function_ref

function_ref::operator=

function_ref::operator()

Deduction guides

Defined in header <functional>

template< class... >
class function_ref; // not defined

(1) (since C++26)

template< class R, class... Args >

class function_ref<R(Args...)>;
template< class R, class... Args >
class function_ref<R(Args...) noexcept>;
template< class R, class... Args >
class function_ref<R(Args...) const>;
template< class R, class... Args >

class function_ref<R(Args...) const noexcept>;

(2) (since C++26)

Class template std::function_ref is a non-owning function wrapper. std::function_ref objects can store and invoke reference to Callable target - functions, lambda expressions, bind expressions, or other function objects, but not pointers to member functions and pointers to member objects. std::nontype can be used to construct std::function_ref by passing function pointers, pointers to member functions, and pointers to member objects.

std::function_refs supports every possible combination of cv-qualifiers (excluding volatile), and noexcept-specifiers provided in its template parameter.

Every specialization of std::function_ref is a TriviallyCopyable type that satisfies copyable.

Contents

[edit] Member types

Member Definition

BoundEntityType (private) unspecified TriviallyCopyable type that satisfies copyable and is capable of storing a pointer to object value or pointer to function value
(exposition-only member type*)

FunctionPointerType (private) R(*)(BoundEntityType , Args&&...) noexcept(noex )

where noex is true if noexcept is present in function signature as part of the template parameter of std::function_ref, false otherwise
(exposition-only member type*)

[edit] Data members

Member Definition

BoundEntityType bound-entity a bound entity object
(exposition-only member object*)

FunctionPointerType thunk-ptr a stored pointer to function
(exposition-only member object*)

[edit] Member functions

constructs a new function_ref object
(public member function) [edit]

assigns a function_ref
(public member function) [edit]

invokes the stored thunk of a function_ref
(public member function) [edit]

[edit] Deduction guides

[edit] Notes

Feature-test macro	Value	Std	Feature
`__cpp_lib_function_ref`	`202306L`	(C++26)	`std::function_ref`

[edit] Example

This section is incomplete
Reason: example

[edit] See also

(C++11)

copyable wrapper of any copy constructible callable object
(class template) [edit]

copyable_function

(C++26)

copyable wrapper of any copy constructible callable object that supports qualifiers in a given call signature
(class template) [edit]

move_only_function

(C++23)

move-only wrapper of any callable object that supports qualifiers in a given call signature
(class template) [edit]

nontype nontype_t

(C++26)

value construction tag
(tag)[edit]

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