std::move_only_function::move_only_function

 

C++

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Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) launder (C++17) initializer_list (C++11) source_location (C++20) Three-way comparison (C++20) three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)    is_eqis_neqis_ltis_lteqis_gtis_gteq (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20) bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator> rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17)

 

Function objects

Function wrappers function (C++11) move_only_function (C++23) mem_fn (C++11) bad_function_call (C++11)	Partial function application bind_frontbind_back (C++20)(C++23) bind (C++11) is_bind_expression (C++11) is_placeholder (C++11) _1, _2, _3, ... (C++11)
Function invocation invokeinvoke_r (C++17)(C++23) Identity function object identity (C++20)	Reference wrappers reference_wrapper (C++11) refcref (C++11)(C++11) unwrap_referenceunwrap_ref_decay (C++20)(C++20)
Operator wrappers plus minus negate multiplies divides modulus bit_and bit_or bit_not (C++14) bit_xor equal_to not_equal_to greater less greater_equal less_equal logical_and logical_or logical_not	Transparent operator wrappers plus<> (C++14) minus<> (C++14) negate<> (C++14) multiplies<> (C++14) divides<> (C++14) modulus<> (C++14) bit_and<> (C++14) bit_or<> (C++14) bit_not<> (C++14) bit_xor<> (C++14) equal_to<> (C++14) not_equal_to<> (C++14) greater<> (C++14) less<> (C++14) greater_equal<> (C++14) less_equal<> (C++14) logical_and<> (C++14) logical_or<> (C++14) logical_not<> (C++14)
Negators not_fn (C++17) Searchers default_searcher (C++17) boyer_moore_searcher (C++17) boyer_moore_horspool_searcher (C++17)	Constrained comparators ranges::equal_to (C++20) ranges::not_equal_to (C++20) ranges::greater (C++20) ranges::less (C++20) ranges::greater_equal (C++20) ranges::less_equal (C++20) compare_three_way (C++20)
Old binders and adaptors
unary_function (until C++17) binary_function (until C++17) ptr_fun (until C++17) pointer_to_unary_function (until C++17) pointer_to_binary_function (until C++17) mem_fun (until C++17) mem_fun_tmem_fun1_tconst_mem_fun_tconst_mem_fun1_t (until C++17)(until C++17)(until C++17)(until C++17) not1 (until C++20) not2 (until C++20)	binder1stbinder2nd (until C++17)(until C++17) bind1stbind2nd (until C++17)(until C++17) mem_fun_ref (until C++17) mem_fun_ref_tmem_fun1_ref_tconst_mem_fun_ref_tconst_mem_fun1_ref_t (until C++17)(until C++17)(until C++17)(until C++17) unary_negate (until C++20) binary_negate (until C++20)

 

std::move_only_function

Member functions

move_only_function::move_only_function (C++23)

move_only_function::~move_only_function (C++23)

move_only_function::operator= (C++23)

move_only_function::swap (C++23)

move_only_function::operator bool (C++23)

move_only_function::operator() (C++23)

Non-member functions

operator== (C++23)

swap(std::move_only_function) (C++23)

 

move_only_function() noexcept;	(1)	(since C++23)
move_only_function( std::nullptr_t ) noexcept;	(2)	(since C++23)
move_only_function( move_only_function&& other ) noexcept;	(3)	(since C++23)
move_only_function( const move_only_function& ) = delete;	(4)	(since C++23)
template< class F > move_only_function( F&& f );	(5)	(since C++23)
template< class T, class... CArgs > explicit move_only_function( std::in_place_type_t<T>, CArgs&&... args );	(6)	(since C++23)
template< class T, class U, class... CArgs > explicit move_only_function( std::in_place_type_t<T>,                              std::initializer_list<U> il, CArgs&&... args );	(7)	(since C++23)

Creates a new std::move_only_function.

1-2) Default constructor and the constructor taking nullptr construct an empty std::move_only_function.

3) Move constructor constructs a std::move_only_function whose target is that of other. other is in a valid but unspecified state after move construction.

4) Copy constructor is deleted. std::move_only_function does not satisfy CopyConstructible.

5) Let VT be std::decay_t<F>. If f is a null function pointer, a null pointer to member function, or an empty std::move_only_function (may be any specialization), then constructs an empty std::move_only_function. Otherwise, constructs a std::move_only_function whose target is of type VT and direct-non-list-initialized with std::forward<F>(f).

• This overload participates in overload resolution only if VT is neither same as move_only_function nor a specialization of std::in_place_type_t, and /*is-callable-from*/<VT> (see below) is true.
• The program is ill-formed if std::is_constructible_v<VT, F> is not true.

6) Let VT be std::decay_t<T>. Constructs a std::move_only_function whose target is of type VT and direct-non-list-initialized with std::forward<CArgs>(args)....

• This overload participates in overload resolution only if both std::is_constructible_v<VT, CArgs...> and /*is-callable-from*/<VT> (see below) are true.
• The program is ill-formed if VT is not the same type as T.

7) Let VT be std::decay_t<T>. Constructs a std::move_only_function whose target is of type VT and direct-non-list-initialized with il, std::forward<CArgs>(args)....

• This overload participates in overload resolution only if both std::is_constructible_v<VT, std::initializer_list<U>&, CArgs...> and /*is-callable-from*/<VT> (see below) are true.
• The program is ill-formed if VT is not the same type as T.

For constructors (5-7), the behavior is undefined if VT does not satisfy the Destructible requirements, or std::is_move_constructible_v<VT> is true but VT does not satisfy the MoveConstructible requirements.

The constant /*is-callable-from*/<VT> is dependent on cv, ref, and noex in the template parameter of std::move_only_function as below:

cv ref noexcept(noex)	/*is-callable-from*/<VT>
noexcept(false)	std::is_invocable_r_v<R, VT, Args...> && std::is_invocable_r_v<R, VT&, Args...>
noexcept(true)	std::is_nothrow_invocable_r_v<R, VT, Args...> && std::is_nothrow_invocable_r_v<R, VT&, Args...>
const noexcept(false)	std::is_invocable_r_v<R, const VT, Args...> && std::is_invocable_r_v<R, const VT&, Args...>
const noexcept(true)	std::is_nothrow_invocable_r_v<R, const VT, Args...> && std::is_nothrow_invocable_r_v<R, const VT&, Args...>
& noexcept(false)	std::is_invocable_r_v<R, VT&, Args...>
& noexcept(true)	std::is_nothrow_invocable_r_v<R, VT&, Args...>
const & noexcept(false)	std::is_invocable_r_v<R, const VT&, Args...>
const & noexcept(true)	std::is_nothrow_invocable_r_v<R, const VT&, Args...>
&& noexcept(false)	std::is_invocable_r_v<R, VT, Args...>
&& noexcept(true)	std::is_nothrow_invocable_r_v<R, VT, Args...>
const && noexcept(false)	std::is_invocable_r_v<R, const VT, Args...>
const && noexcept(true)	std::is_nothrow_invocable_r_v<R, const VT, Args...>

Parameters

other	-	another std::move_only_function to move from
f	-	a function or a Callable object to wrap
args	-	arguments to construct the target object
il	-	std::initializer_list to construct the target object

Exceptions

5-7) May throw std::bad_alloc on allocation failure or propagate the exception thrown by the initialization of the target. No exception is thrown if VT is a function pointer type or a specialization of std::reference_wrapper.

See also

(constructor)

constructs a new std::function instance (public member function of std::function<R(Args...)>)