This constructor creates a new shared state that becomes satisfied when both rhs and rhs.get() become satisfied. If rhs is satisfied, but rhs.get() returns an invalid future then the newly created future becomes satisfied with a std::future_error exception, and the exception error code is std::future_errc::broken_promise.
Parameter
Name
Description
rhs
future< future< T > > &&
future(future< U > &&)
Creates a future from a future whose result type is convertible to this future's result type.
Parameters
Name
Description
rhs
future< U > &&
class U
typename Enable
future(std::shared_ptr< shared_state_type >)
Parameter
Name
Description
state
std::shared_ptr< shared_state_type >
Functions
get()
Waits until the shared state becomes ready, then retrieves the value stored in the shared state.
Exceptions
Type
Description
...
any exceptions stored in the shared state.
std::future_error
with std::no_state if the future does not have a shared state.
Returns
Type
Description
T
then(F &&)
Attach a continuation to the future.
Attach a callable func to be invoked when the future is ready. The return type is a future wrapping the return type of func.
Side effects: valid() == false if the operation is successful.
Parameters
Name
Description
func
F &&
a Callable to be invoked when the future is ready. The function might be called immediately, e.g., if the future is ready.
typename F
Returns
Type
Description
future< >
future<T> where T is std::result_of_t<F, R> (basically). If T matches future<U> then it returns future<U>. The returned future will contain the result of func.
Type Aliases
shared_state_type
Alias Of: typename internal::future_base< T >::shared_state_type
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-05 UTC."],[[["This page provides documentation for the `future\u003cT\u003e` class, as implemented in ISO/IEC TS 19571:2016."],["The documentation details various versions of the `future\u003cT\u003e` class, ranging from version 2.10.1 to the latest release candidate, 2.37.0-rc."],["It covers different constructors for `future\u003cT\u003e`, including one for unwrapping nested futures (`future\u003c future\u003c T \u003e \u003e`) and another for converting from futures with compatible result types."],["The `get()` function is explained, which retrieves the value stored in the shared state of the future, with the caveat that subsequent calls will fail."],["The page documents the `then(F &&)` function that allows attaching a continuation function to the future, which will be invoked when the future is ready and will return a new future containing the results of that function."]]],[]]
