std::uses_allocator<std::function>

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Library feature-test macros
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
integer_sequence (C++14)
Relational operators (deprecated in C++20)
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Comparisons (C++20)
strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
common_comparison_category
Common vocabulary types
pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Elementary string conversions
to_chars (C++17)
from_chars (C++17)
chars_format (C++17)
Type operations
declval (C++11)
as_const (C++17)
launder (C++17)

 

Function objects

Function wrappers function (C++11) mem_fn (C++11) bad_function_call (C++11)	Partial function application bind_front (C++20) bind (C++11) is_bind_expression (C++11) is_placeholder (C++11) _1, _2, _3, ... (C++11)
Function invocation invoke (C++17) 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 logical_and logical_or logical_not	equal_to not_equal_to greater less greater_equal less_equal bit_and bit_or bit_xor bit_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)
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::function

Member functions

function::function

function::~function

function::operator=

function::swap

function::assign (until C++17)

function::operator bool

function::operator()

function::target_type

function::target

Non-member functions

operator==operator!=

std::swap(std::function)

Helper classes

std::uses_allocator<std::function> (until C++17)

Deduction guides(C++17)

 

Defined in header <functional>
template< class R, class... ArgTypes, class Alloc > struct uses_allocator<std::function<R(ArgTypes...)>, Alloc> : std::true_type { };		(since C++11) (until C++17)

This specialization of std::uses_allocator informs other library components that all objects of type std::function support uses-allocator construction, even though they do not have a nested allocator_type.

Notes

std::function's allocator support was poorly specified and inconsistently implemented. Some implementations do not support uses-allocator construction at all, some provide the needed constructor overloads but ignore the supplied allocator argument, and some provide the overloads and use the supplied allocator for construction but not when the std::function is reassigned. As a result, allocator support was removed in C++17.

Inherited from std::integral_constant

Member constants

value [static]

true (public static member constant)

Member functions

operator bool	converts the object to bool, returns value (public member function)
operator() (C++14)	returns value (public member function)

Member types

Type	Definition
value_type	bool
type	std::integral_constant<bool, value>

See also

uses_allocator (C++11)

checks if the specified type supports uses-allocator construction (class template)