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An use case for synthetic events in Kotlin
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| /** | |
| * This is a generic event class. It simply allows subscription and invocation. | |
| */ | |
| class Event<T> { | |
| private val handlers = arrayListOf<(Event<T>.(T) -> Unit)>() | |
| operator fun plusAssign(handler: Event<T>.(T) -> Unit) { handlers.add(handler) } | |
| operator fun invoke(value: T) { for (handler in handlers) handler(value) } | |
| } | |
| /** | |
| * Each controller would have a companion object which would be the event emitted by | |
| * each endpoint. The event would be a tuple of the function invoked and its payload. | |
| */ | |
| class SomeController { | |
| companion object { | |
| var eventEmitted = Event<Pair<String, String>>() | |
| } | |
| fun post(body: Any): String { | |
| // Ideally this "eventEmitted" invocation could be abstracted away in a parent class? | |
| eventEmitted(Pair("SomeController::post", "post method invoked")) | |
| return "Return POST value" | |
| } | |
| fun get(): String { | |
| eventEmitted(Pair("SomeController::get", "get method invoked")) | |
| return "Return GET value" | |
| } | |
| } | |
| /** | |
| * The Notifications is the one which handles which events trigger which logic. Potentially there could | |
| * be some sugar syntax applied here to not have to do the whole if/then ceremony. | |
| */ | |
| class NotificationsManager { | |
| fun setupEvents() { | |
| SomeController.eventEmitted += { if (it.first == "SomeController::get") println("get's event payload >>> ${it.second}") } | |
| SomeController.eventEmitted += { if (it.first == "SomeController::post") println("post's event payload >>> ${it.second}") } | |
| } | |
| } | |
| /** | |
| * Runnable example :) | |
| */ | |
| fun main(args : Array<String>) { | |
| val controller = SomeController() | |
| NotificationsManager().setupEvents() | |
| controller.get() | |
| controller.get() | |
| controller.post("") | |
| } |
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