std::execution::then

 

C++

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Execution control library

Execution concepts scheduler receiver receiver_of operation_state    sender sender_in sender_to Execution components Execution contexts run_loop Execution domains default_domain Forward progress guarantee forward_progress_guarantee Environments empty_env    get_env    env_of_t Queries std::stop_token_of_t std::get_stop_token std::get_allocator std::forwarding_query get_scheduler get_domain get_forward_progress_guarantee get_delegation_scheduler get_completion_scheduler Completion signatures completion_signatures completion_signatures_of_t transform_completion_signatures transform_completion_signatures_of    value_types_of_t error_types_of_t    tag_of_t sends_stopped    Sender adaptor closures sender_adaptor_closure Coroutine utility as_awaitable with_awaitable_senders

Core operations Operation state connect connect_result_t start Completion set_value set_error set_stopped Transformation transform_env transform_sender apply_sender Sender algorithms Sender factories just just_error just_stopped read_env schedule schedule_result_t Sender adaptors starts_on continues_on    on then upon_error upon_stopped let_value let_error let_stopped schedule_from when_all when_all_with_variant into_variant stopped_as_optional stopped_as_error bulk split Sender consumers this_thread::sync_wait this_thread::sync_wait_with_variant

 

Defined in header <execution>
execution::sender auto then( execution::sender auto input,                              std::invocable</*values-sent-by*/(input)...> function );		(since C++26)

Parameters

input	-	sender which once executed sends the values upon which the function executes
function	-	invocable to be called by the new sender chained to the input sender

Return value

Returns a sender describing the task graph described by the input sender, with an added node of invoking the provided function with the values sent by the input sender as arguments.

then is guaranteed to not begin executing function until the returned sender is started.

Example

Possible usage of execution::then.

execution::sender auto input = get_input();
execution::sender auto snd = execution::then(input, [](auto... args)
{
    std::print(args...);
});
/ snd describes the work described by pred
/ followed by printing all of the values sent by pred

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