best_view_error_handling.kt

fun Fragment.handleErrors(error:Throwable) {
 when (error) {
   is NoInternetConnectionException -> snackbar(view, R.string.general_no_connection_error)
   is GeneralServerException -> snackbar(view, R.string.general_server_error)
   else -> throw error
 }
}



class LoginFragment : Fragment {
 val viewModel: LoginViewModel
 var disposables: CompositeDisposable

 fun onViewCreated() {
   disposables += viewModel.observeLoginResult()
       .observeOnMainThread()
       .subscribe {
         when (it) {
           is LoginResult.LoginOk -> finishLogin()
           is LoginResult.LoginError -> {
             when (it.error) {
               is InvalidCredentialsException -> showInvalidCredentialsError()
               is ValidationException -> showValidationErrors(it.error.errors)
               else -> handleErrors(it.error)
             }
           }
         }
       }
 }
}