std::experimental::promise (library fundamentals TS)

 

C++

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Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

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Strings library

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Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals 2 TS)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Concepts (concepts TS)

Ranges (ranges TS)

Special mathematical functions (special math TR)

 

Library fundamentals

experimental::optional

experimental::any

experimental::basic_string_view

experimental::sample

experimental::shared_ptr

experimental::weak_ptr

experimental::apply

experimental::invocation_type experimental::raw_invocation_type

experimental::search

experimental::default_searcher experimental::make_default_searcher

experimental::boyer_moore_searcher experimental::make_boyer_moore_searcher

experimental::boyer_moore_horspool_searcher experimental::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

 

This page is about the modified version of std::promise with type-erased allocator support provided by the Library Fundamentals TSes. For the version of promise provided by the concurrency TS supporting the std::future improvements made by that TS, see std::experimental::concurrency_v1::promise.

Defined in header <experimental/future>
template< class R > class promise;	(1)	(library fundamentals TS)
template< class R > class promise<R&>;	(2)	(library fundamentals TS)
template<>          class promise<void>;	(3)	(library fundamentals TS)

std::experimental::fundamentals_v1::promise (and std::experimental::fundamentals_v2::promise) is a modified version of std::promise provided by the library fundamentals TS with support for type-erased allocators.

Member types

Member type	Definition
allocator_type	std::experimental::erased_type

Member functions

(constructor)	constructs the promise object (public member function)
get_memory_resource	retrieves a pointer to the memory resource used by this object to allocate memory (public member function)

Non-member function

std::experimental::swap(std::experimental::promise)

specializes the swap algorithm (function template)

Helper classes

std::uses_allocator<std::experimental::promise>

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

Members identical to std::promise

Member functions

(destructor)	destructs the promise object (public member function of std::promise<R>)
operator=	assigns the shared state (public member function of std::promise<R>)
swap	swaps two promise objects (public member function of std::promise<R>)
Getting the result
get_future	returns a future associated with the promised result (public member function of std::promise<R>)
Setting the result
set_value	sets the result to specific value (public member function of std::promise<R>)
set_value_at_thread_exit	sets the result to specific value while delivering the notification only at thread exit (public member function of std::promise<R>)
set_exception	sets the result to indicate an exception (public member function of std::promise<R>)
set_exception_at_thread_exit	sets the result to indicate an exception while delivering the notification only at thread exit (public member function of std::promise<R>)