Platform: Question: Example-app, why extend the root state?

[bhaidar]

Hello,
In this class, you extend the root State by adding additional state.
https://github.com/ngrx/platform/blob/master/example-app/app/auth/reducers/index.ts

export interface State extends fromRoot.State { auth: AuthState; }
why are you extending the fromRoot.State into a new interface State? Where do you use this new State interface? Are you adding a new state into the root State? Where do you use the states from the root State? Just in core module or also in feature modules?

Thanks

[brandonroberts]

Support questions should be asked on stackoverflow or the gitter channel.

[bhaidar]

Thanks @brandonroberts I asked there and no one answered me!

[brandonroberts]

Ok. The root state interface is being extended so you get type information when using selectors and if you're using the feature state as the Store<T> in your components. If your feature module is completely independent of the root state, then you don't need to extend from the root state interface.