HowToAddAnEventToAClass.md

How to add an event to a class?

Adding an event to a class is pretty easy. Expose it an an IEvent<TSender, TArgs> or ISimpleEvent<TArgs> and implement it as a dispatcher (EventDispatcher or SimpleEventDispatcher).

Example

Conside the following example:

class MyClass
{
	private _myEvent = new EventDispatcher<MyClass, string>();
	
	public get onMyEvent(): IEvent<MyClass, string>
	{
		return this._myEvent.asEvent();
	}

	public signal(message: string)
	{
		if(message) {
			this._myEvent.dispatch(this, message);	
		}
	}
}

The event itself is exposed by a getter. The implementation can return the entire event dispatcher or class the asEvent() on the dispatcher to return a wrapper with the dispatcher.

Usage

Subscibing to an event is pretty straight forward:

let myObject = new MyClass();
myObject.onMyEvent.subscribe((s: MyClass, a: string) => {
	alert(s);
});

An event handler can be unsubscribed like this:

let unsubscribe = myObject.onMyEvent.subscribe((s: MyClass, a: string) => {
	alert(s);
});
unsubscribe();

Event methods

The IEvent<TSender, TArgs>, ISimple<TArgs>, EventDispatcher<TSender, TArgs>, SimpleEvenDispatcher<TArgs> share the same basic methods:

• subscribe(eventHandler) - subscribes to the event by registring an event handler. The handler will be executed when the event is dispatched. The subscribe method returns a function that can be used to unsubscribe the eventHandler directly.
• unsubscribe(eventHandler) - removes the subscription by removing the handler. This will stop the handler from being executed when the event is dispatched.

Only the EventDispatcher<TSender, TArgs> and SimpleEvenDispatcher<TArgs> have a dispatch method:

• dispatch(args) - dispatches the event by calling all the registered event handler with the arguments.