EventEmitter class

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

Constructors

EventEmitter()

Properties

count → int

Get the unique count of events registered in the emitter.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

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 nonexistent method or property is accessed.

inherited

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.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited