Pingora class

The base class for creating ViewModels / Controllers that can notify listeners about state changes.

Extend this class to create a stateful controller, then use subscribe to listen for updates, ping to notify all listeners, unsubscribe to remove a listener, and dispose to permanently shut down the controller.

class CounterModel extends Pingora {
  int count = 0;

  void increment() {
    count++;
    ping(); // notify all subscribers
  }
}

Once dispose is called, any further calls to subscribe, unsubscribe, or ping will throw an AssertionError to catch bugs early.