EventEmitter class Null safety

This class provides necessary implementations for subscribing and cancelling the event subscriptions and publishing events to the subcribers.




count int
Get the unique count of events registered in the emitter.
hashCode int
The hash code for this object. [...]
read-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


clear() → void
Clear all subscribers from the cache.
emit(String event, [Object? sender, Object? data]) → void
API to emit events. event is a required parameter. If sender information is sent, it will be used to intimate user about it. event - What event needs to be emitted. sender - The sender who published the event. Ignore if not required. data - Data the event need to carry. Ignore this argument if no data needs to be sent.
getListenersCount(String event) int
Get the list of subscribers for a particular event.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
off(Listener? listener) → void
Remove event listener from emitter. This will unsubscribe the caller from the emitter from any future events. Listener should be a valid instance. listener - Listener instance to be removed from the event subscription.
on(String event, Object? context, EventCallback callback) Listener
API to register for notification. It is mandatory to pass event name and callback parameters. event - Event name used for the subscription. A valid event name is mandatory. context - Context information, which need to be sent in all emitted events. callback - EventCallback function registered to receive events emitted from the publisher. A valid callback function is mandatory.
removeAllByCallback(EventCallback callback) → void
Remove all listeners which matches with the callback provided. It is possible to register for multiple events with a single callback. This mechanism ensure that all event registrations would be cancelled which matches the callback. callback - The event callback used during subscription.
removeAllByEvent(String event) → void
Use this mechanism to remove all subscription for a particular event. Caution : This will remove all the listeners from multiple files or classes or modules. Think twice before calling this API and make sure you know what you are doing!!! event - Event name used during subscription.
removeListener(String eventName, EventCallback callback) → void
Unsubscribe from getting any future events from emitter. This mechanism uses event name and callback to unsubscribe from all possible events. eventName - Event name for the subscription. callback - EventCallback used when registering subscription using on function.
toString() String
A string representation of this object. [...]


operator ==(Object other) bool
The equality operator. [...]