std::function_ref::function_ref

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

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

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

 constructs a new std::move_only_function object
(public member function of std::move_only_function)
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