An example of the ELM architecture applied to Android using Kotlin with Anko.
The MainActivity defines a dispatch method (outside of its scope).
The dispatch method :
updatethe modelrendera view for the updated modelsetContentViewwith the view representing the updated model.
onCreate the activity initialize the system with an INIT action and a new Model.
public class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
dispatch(this)
}
}
fun dispatch(activity: Activity, action: Action = Action.INIT, model: Model = Model()) {
val updatedModel = update(action, model)
val dispatch = dispatch(activity, updatedModel)
activity.setContentView(view(activity, updatedModel, dispatch))
}
fun dispatch(activity: Activity, model: Model) = { newAction: Action ->
dispatch(activity, newAction, model)
}
All the application logic is in Counter.kt.
The file
- declares the
Model - declares the
Action - implements the
updatefunction - implements the
viewfunction
sealed class Action {
object INIT : Action()
object UP : Action()
object DOWN : Action()
}
data class Model(val counter: Int = 0)
fun update(action: Action, model: Model): Model {
return when (action) {
is Action.INIT -> Model()
is Action.UP -> Model(model.counter + 1)
is Action.DOWN -> Model(model.counter - 1)
}
}
fun view(context: Context, model: Model, dispatch : (Action) -> Unit): LinearLayout {
with(context) {
return verticalLayout {
button("up") {
onClick { dispatch(Action.UP) }
}
button("down") {
onClick { dispatch(Action.DOWN) }
}
textView(model.counter.toString())
}
}
}
This is experimental and made for a talk. Feedback welcomed.