std::function_ref::function_ref
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std::function_ref
function_ref::function_ref
template< class F >
function_ref( F* f ) noexcept;
(1)
(since C++26)
function_ref( F* f ) noexcept;
template< class F >
function_ref( F&& f ) noexcept;
(2)
(since C++26)
function_ref( F&& f ) noexcept;
template< auto f >
function_ref( std::nontype_t <f> ) noexcept;
(3)
(since C++26)
function_ref( std::nontype_t <f> ) noexcept;
template< auto f, class U >
function_ref( std::nontype_t <f>, U&& obj ) noexcept;
(4)
(since C++26)
function_ref( std::nontype_t <f>, U&& obj ) noexcept;
template< auto f, class T >
function_ref( std::nontype_t <f>, /*cv*/ T* obj ) noexcept;
(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
function_ref, - std::is_member_pointer_v <T> is false, and
- /*is-invocable-using*/</*cv*/ T&> is true.
- std::remove_cvref_t <F> is not the same type as
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
[edit] Parameters
other
-
another
function_ref to copy from
f
-
a function or a Callable object to wrap
obj
-
an object or pointer to bound
[edit] Example
This section is incomplete
Reason: no example
Reason: no example
[edit] See also
constructs a new
(public member function of
std::move_only_function object (public member function of
std::move_only_function) [edit]