This is a simple library for implementing event subscription APIs.
Implementing Event Subscription APIs
const { Emitter } = require("@sbspk/disposable");
class User {
constructor() {
this.emitter = new Emitter();
}
onDidChangeName(callback) {
this.emitter.on("did-change-name", callback);
}
setName(name) {
if (name !== this.name) {
this.name = name;
this.emitter.emit("did-change-name", name);
}
return this.name;
}
destroy() {
this.emitter.dispose();
}
}In the example above, we implement ::onDidChangeName on the user object, which
will register callbacks to be invoked whenever the user's name changes. To do
so, we make use of an internal Emitter instance. We use ::on to subscribe
the given callback in ::onDidChangeName, and ::emit in ::setName to notify
subscribers. Finally, when the User instance is destroyed we call ::dispose
on the emitter to unsubscribe all subscribers.
Consuming Event Subscription APIs
Emitter::on returns a Disposable instance, which has a ::dispose method.
To unsubscribe, simply call dispose on the returned object.
const subscription = user.onDidChangeName((name) =>
console.log(`My name is ${name}`)
);
// Later, to unsubscribe...
subscription.dispose();You can also use CompositeDisposable to combine disposable instances together.
const { CompositeDisposable } = require('@sbspk/disposable')
const subscriptions = new CompositeDisposable()
subscriptions.add(user1.onDidChangeName((name) => console.log(`User 1: ${name}`))
subscriptions.add(user2.onDidChangeName((name) => console.log(`User 2: ${name}`))
// Later, to unsubscribe from *both*...
subscriptions.dispose()Creating Your Own Disposables
Disposables are convenient ways to represent a resource you will no longer need at some point. You can instantiate a disposable with an action to take when no longer needed.
const { Disposable } = require("@sbspk/disposable");
const disposable = new Disposable(() => this.destroyResource());