std::experimental::function

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Experimental

Technical Specification

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Extensions for concurrency 2 (concurrency TS v2)

Concepts (concepts TS)

Ranges (ranges TS)

Reflection (reflection TS)

Mathematical special functions (special functions TR)

Experimental Non-TS

Pattern Matching

Linear Algebra

std::execution

Contracts

2D Graphics

 

Library fundamentals

experimental::optional

experimental::any

experimental::basic_string_view

experimental::sample

experimental::shared_ptr

experimental::weak_ptr

experimental::apply

experimental::invocation_typeexperimental::raw_invocation_type

experimental::search

experimental::default_searcherexperimental::make_default_searcher

experimental::boyer_moore_searcherexperimental::make_boyer_moore_searcher

experimental::boyer_moore_horspool_searcherexperimental::make_boyer_moore_horspool_searcher

Type-erased and polymorphic allocators

Variable templates for type traits

 

Polymorphic allocator library

polymorphic_allocator

Convenience aliases for containers using polymorphic_allocator

Memory resource classes

memory_resource

synchronized_pool_resource

unsynchronized_pool_resource

monotonic_buffer_resource

resource_adaptor

Global memory resources

new_delete_resource

null_memory_resource

get_default_resource

set_default_resource

Type-erased allocator support for existing classes

function

packaged_task

promise

 

Defined in header <experimental/functional>
template< class > class function; /* undefined */		(library fundamentals TS)
template< class R, class... Args > class function<R(Args...)>		(library fundamentals TS)

std::experimental::function is a modified version of std::function with support for type-erased allocators.

Member types

Type	Definition
allocator_type	std::experimental::erased_type (library fundamentals TS) (until library fundamentals TS v3) std::pmr::polymorphic_allocator<> (library fundamentals TS v3)

Member functions

(constructor)	constructs a new std::experimental::function instance (public member function)
operator=	assigns a new target (public member function)
swap	swaps the contents (public member function)
get_memory_resource (removed in library fundamentals TS v3)	retrieves a pointer to the memory resource used by this object to allocate memory (public member function)
get_allocator (library fundamentals TS v3)	retrieves a type-erased std::pmr::polymorphic_allocator used by this object to allocate memory (public member function)

Non-member functions

std::experimental::swap(std::experimental::function)	specializes the swap algorithm (function template)
operator==operator!= (removed in library fundamentals TS v3)	compares an std::experimental::function with nullptr (function template)

Helper classes

std::uses_allocator<std::experimental::function> (removed in library fundamentals TS v3)

specializes the std::uses_allocator type trait (class template specialization)

Members identical to std::function

Member types

Type	Definition
result_type	R
Member types removed in Library Fundamental TS v3
argument_type	T if sizeof...(Args) == 1 and T is the first and only type in Args...
first_argument_type	T1 if sizeof...(Args) == 2 and T1 is the first of the two types in Args...
second_argument_type	T2 if sizeof...(Args) == 2 and T2 is the second of the two types in Args...

Member types argument_type, first_argument_type, and second_argument_type are removed, because the correponding member types of std::function are removed in C++20.

(library fundamentals TS v3)

Member functions

(destructor)	destroys a std::function instance (public member function of std::function<R(Args...)>)
operator bool	checks if a target is contained (public member function of std::function<R(Args...)>)
operator()	invokes the target (public member function of std::function<R(Args...)>)
Target access
target_type	obtains the typeid of the stored target (public member function of std::function<R(Args...)>)
target	obtains a pointer to the stored target (public member function of std::function<R(Args...)>)