Struct EventListener 

pub struct EventListener { /* private fields */ }

A listener to an Event. It completes when a notification reaches it.

Event::listen creates one and puts it at the back of the event’s queue. Every notification sent from then on can reach it, even if it has not been polled yet.

A notification that reaches the listener wakes the task that polled it last, and the listener completes on its next poll. Polling it again after it completed returns Ready at once.

Dropping a listener

Dropping a listener removes it from the queue. If the listener was notified but had not completed, it passes its notification on to the next listener:

• If Event::notify sent the notification, the next listener gets it only if no other listener is notified at that point.
• If Event::notify_additional sent it, the next listener always gets it.

Passing a notification on wakes the next listener’s task, so a waker that panics can make the drop panic.

Outliving the event

A listener can outlive its Event. Dropping the event notifies nobody. A listener that was notified before that still completes. One that was not stays pending, unless a notified listener passes its notification on to it when dropped.

Trait Implementations

impl Debug for EventListener

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for EventListener

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl Future for EventListener

type Output = ()

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.