ViewActivity.kt

abstract class ViewActivity<T : ControllerView> : AppCompatActivity() {

    lateinit var controllerView: T

    override fun onStart() {
        super.onStart()
        controllerView.onStart()
    }
    
    //^^ We will do the same with every activity/fragment 
    //state that we want our ControllerView tracks

    protected fun registerControllerViewForLifecycle(controllerView: T) {
        this.controllerView = controllerView
    }

    abstract fun setupControllerView()
}