std::function_ref::function_ref

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std::function_ref
 
template< class F >
function_ref( F* f ) noexcept;
 (1) (since 哋它亢++26)
template< class F >
function_ref( F&& f ) noexcept;
 (2) (since 哋它亢++26)
template< auto f >
function_ref( std::nontype_t<f> ) noexcept;
 (3) (since 哋它亢++26)
template< auto f, class U >
function_ref( std::nontype_t<f>, U&& obj ) noexcept;
 (4) (since 哋它亢++26)
template< auto f, class T >
function_ref( std::nontype_t<f>, /*cv*/ T* obj ) noexcept;
 (5) (since 哋它亢++26)
function_ref( const function_ref& other ) = default;
 (6) (since 哋它亢++26)

Creates a new std::function_ref.

1) Initializes bound-entity with f, and thunk-ptr with the address of a function thunk. The behavior is undefined if f is a null pointer.
  • This overload participates in overload resolution only if both std::is_function_v<F> and /*is-invocable-using*/<F> are true.
2) Initializes bound-entity with std::addressof(f), and thunk-ptr with the address of a function thunk.
3) Initializes bound-entity with a pointer to an unspecified object or null pointer value, and thunk-ptr with the address of a function thunk.
  • Let F be decltype(f). This overload participates in overload resolution only if /*is-invocable-using*/<F> is true.
  • The program is ill-formed if f != nullptr is false when std::is_pointer_v<F> || std::is_member_pointer_v<F> is true.
4) Initializes bound-entity with std::addressof(obj), and thunk-ptr with the address of a function thunk.
5) Initializes bound-entity with obj, and thunk-ptr with the address of a function thunk. The behavior is undefined if obj is a null pointer when std::is_member_pointer_v<F> is true.
  • Let F be decltype(f). This overload participates in overload resolution only if /*is-invocable-using*/<F, /*cv*/ T*> is true.
  • The program is ill-formed if f != nullptr is false when std::is_pointer_v<F> || std::is_member_pointer_v<F> is true.
6) Defaulted copy constructor copies the bound-entity and thunk-ptr of other.

The address of a function thunk is used to initialize thunk-ptr such that a call to thunk(bound-entity, call-args...) is expression-equivalent to:

Overloads Expression-equivalence
(1,3) std::invoke_r<R>(f, call-args...)
(2) std::invoke_r<R>(static_cast<cv T&>(f), call-args...)
(4) std::invoke_r<R>(f, static_cast<cv T&>(obj), call-args...)
(5) std::invoke_r<R>(f, obj, call-args...)

/*is-invocable-using*/<T...> is true if and only if:

Parameters

other - another function_ref to copy from
f - a function or a Callable object to wrap
obj - an object or pointer to bound

Example

This section is incomplete
Reason: no example

See also

(哋它亢++23)
 constructs a new std::move_only_function object
(public member function of std::move_only_function)
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