Proposal: Expose class methods on the app instance level

[rbardini]

Currently

We can declare methods inside createApp to expose application-specific behavior:

const FooApp = createApp({
  name: 'Foo',
  bar() { // exposed method
    console.log('bar')
  }
})

This requires accessing the options property of the app instance to retrieve the methods from another app:

const BazComponent = observe(app =>
  streamProps()
    .set({
      foo: app.get('foo').options.bar, // retrieve `bar` method out of `foo` app options
    })
    .get$()
)(({ bar }) => /* `bar` method as prop */)

const BazApp = createApp({
  name: 'Baz',
  providers: [
    {
      name: 'component',
      useValue: BazComponent,
    },
    {
      name: 'foo',
      deps: ['rootApp'],
      useFactory({ rootApp }) {
        return rootApp.getAppInstance('Foo')
      }
    }
  ]
})

Proposal

Add a new, optional methods (Object) property to the options argument of createApp, which has its properties added to the app's this object, thus allowing us to access the methods directly from the app instance:

const FooApp = createApp({
  name: 'Foo',
  methods: { // specify what methods this app exposes
    bar() {
      console.log('bar')
    }
  }
})

const BazComponent = observe(app =>
  streamProps()
    .set({
      foo: app.get('foo').bar, // retrieve `bar` method out of `foo` app directly
    })
    .get$()
)(({ bar }) => /* `bar` method as prop */)

const BazApp = createApp({
  name: 'Baz',
  providers: [
    {
      name: 'component',
      useValue: BazComponent,
    },
    {
      name: 'foo',
      deps: ['rootApp'],
      useFactory({ rootApp }) {
        return rootApp.getAppInstance('Foo')
      }
    }
  ]
})