std::experimental::future

 

C++

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Freestanding and hosted

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Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

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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)

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Reflection (reflection TS)

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Experimental Non-TS

Pattern Matching

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2D Graphics

 

Extensions for concurrency

std::future extensions

experimental::future

experimental::shared_future

experimental::when_all

experimental::when_any

experimental::make_ready_future

experimental::make_exceptional_future

Latches and barriers

experimental::latch

experimental::barrier

experimental::flex_barrier

Atomic smart pointers

experimental::atomic_shared_ptr

experimental::atomic_weak_ptr

 

std::experimental::future

future::future

future::operator=

future::is_ready

future::then

 

Defined in header <experimental/future>
template< class T > class future;	(1)	(concurrency TS)
template< class T > class future<T&>;	(2)	(concurrency TS)
template<> class future<void>;	(3)	(concurrency TS)

The class template std::experimental::future extends std::future with the following operations:

• an unwrapping constructor from future<future<T>>;
• a member function is_ready to query whether the associated shared state is ready; and
• a member function then to attach a continuation to the future.

However, there is no interoperation between std::experimental::future and std::future.

Member functions

(constructor)	construct a future object (public member function)
is_ready	checks if the shared state is ready (public member function)
then	attaches a continuation to a future (public member function)
operator=	moves the future object (public member function)

Members identical to std::future

Member functions

Note that share() returns a std::experimental::shared_future<T>. The behavior is otherwise identical.

(destructor)	destructs the future object (public member function of std::future<T>)
share	transfers the shared state from *this to a shared_future and returns it (public member function of std::future<T>)
Getting the result
get	returns the result (public member function of std::future<T>)
State
valid	checks if the future has a shared state (public member function of std::future<T>)
wait	waits for the result to become available (public member function of std::future<T>)
wait_for	waits for the result, returns if it is not available for the specified timeout duration (public member function of std::future<T>)
wait_until	waits for the result, returns if it is not available until specified time point has been reached (public member function of std::future<T>)

See also

shared_future (concurrency TS)

a version of std::shared_future enhanced with continuations and other features (class template)