EmitterInterface
in
Event Emitter Interface
Anything that accepts listeners and emits events should implement this interface.
Tags
Table of Contents
Methods
- emit() : void
- Emits an event.
- listeners() : array<string|int, callable>
- Returns the list of listeners for an event.
- on() : void
- Subscribe to an event.
- removeListener() : bool
- Removes a specific listener from an event.
Methods
emit()
Emits an event.
public
emit(string $eventName[, array<int, mixed> $arguments = [] ][, callable|null $continueCallBack = null ]) : void
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.
Parameters
- $eventName : string
- $arguments : array<int, mixed> = []
- $continueCallBack : callable|null = null
listeners()
Returns the list of listeners for an event.
public
listeners(string $eventName) : array<string|int, callable>
The list is returned as an array, and the list of events are sorted by their priority.
Parameters
- $eventName : string
Return values
array<string|int, callable>on()
Subscribe to an event.
public
on(string $eventName, callable $callBack[, int $priority = 100 ]) : void
Parameters
- $eventName : string
- $callBack : callable
- $priority : int = 100
removeListener()
Removes a specific listener from an event.
public
removeListener(string $eventName, callable $listener) : bool
If the listener could not be found, this method will return false. If it was removed it will return true.
Parameters
- $eventName : string
- $listener : callable