Trait Sabre\Event\EmitterTrait

Event Emitter Trait.

This trait contains all the basic functions to implement an EventEmitterInterface.

Using the trait + interface allows you to add EventEmitter capabilities without having to change your base-class.

Sabre\Event\EmitterTrait
- Sabre\Event\EventEmitter implements EmitterInterface uses EmitterTrait
  - Sabre\HTTP\Client
    - Sabre\DAV\Client
      - Afterlogic\DAV\Client

Methods
`public`	`on(string $eventName, callable $callBack, int $priority = 100)` Subscribe to an event. Subscribe to an event.	#
`public`	`once(string $eventName, callable $callBack, int $priority = 100)` Subscribe to an event exactly once. Subscribe to an event exactly once.	#
`public`	`emit(string $eventName, array $arguments = [], callable $continueCallBack = null): bool` Emits an event. Emits an event. This method will return true if 0 or more listeners were successfully handled. false is returned if one of the events broke the event chain. If the continueCallBack is specified, this callback will be called every time before the next event handler is called. If the continueCallback returns false, event propagation stops. This allows you to use the eventEmitter as a means for listeners to implement functionality in your application, and break the event loop as soon as some condition is fulfilled. Note that returning false from an event subscriber breaks propagation and returns false, but if the continue-callback stops propagation, this is still considered a 'successful' operation and returns true. Lastly, if there are 5 event handlers for an event. The continueCallback will be called at most 4 times.	#
`public`	`listeners(string $eventName): callable[]` Returns the list of listeners for an event. Returns the list of listeners for an event. The list is returned as an array, and the list of events are sorted by their priority.	#
`public`	`removeListener(string $eventName, callable $listener): bool` Removes a specific listener from an event. Removes a specific listener from an event. If the listener could not be found, this method will return false. If it was removed it will return true.	#
`public`	`removeAllListeners(string $eventName = null)` Removes all listeners. Removes all listeners. If the eventName argument is specified, all listeners for that event are removed. If it is not specified, every listener for every event is removed.	#