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std::functi...function_ref(3) C++ Standard Libarystd::functi...function_ref(3)

NAME
       std::function_ref::function_ref - std::function_ref::function_ref

Synopsis
	  template<   class   F	 >					   (1)
       (since C++26)
	  function_ref(	F* f ) noexcept;
	  template<  class  F	>					   (2)
       (since C++26)
	  function_ref(	F&& f )	noexcept;
	  template<   auto   f	>					   (3)
       (since C++26)
	  function_ref(	std::nontype_t<f> ) noexcept;
	  template<  auto  f,  class  U	 >				   (4)
       (since C++26)
	  function_ref(	std::nontype_t<f>, U&& obj ) noexcept;
	  template<  auto  f,  class  T	 >				   (5)
       (since C++26)
	  function_ref(	std::nontype_t<f>, /*cv*/ T* obj ) noexcept;
	  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.
	    *  Let T be	std::remove_reference_t<F>. This overload participates
       in overload
	      resolution only if :
		 * std::remove_cvref_t<F>  is  not  the	 same  type  as	 func-
       tion_ref,
		 * std::is_member_pointer_v<T> is false, and
		 * /*is-invocable-using*/</*cv*/ T&> is	true.
	  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.
	    *  Let  T be std::remove_reference_t<U> and	F be decltype(f). This
       overload
	      participates in overload resolution only if :
		 * std::is_rvalue_reference_v<U&&> is false, and
		 * /*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.
	  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:

	    * std::is_nothrow_invocable_r_v<R, T..., Args...> is true if  noex
       is true,	or
	    * std::is_invocable_r_v<R, T..., Args...> 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
	  constructor	constructs a new std::move_only_function object
	  (C++23)	(public	member function	of std::move_only_function)

Category:
	    * Todo no example

http://cppreference.com		  2024.06.10	 std::functi...function_ref(3)

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