readme

Author: hoc081098

README.md

@@ -1,5 +1,7 @@
 # DemoCoroutinesChannelResult
 
+Use `Kotlinx Coroutines Channel` to send and receive events between Fragments.
+
 ## Author: [Petrus Nguyễn Thái Học](https://github.com/hoc081098)
 
 [![Hits](https://hits.seeyoufarm.com/api/count/incr/badge.svg?url=https%3A%2F%2Fgithub.com%2Fhoc081098%2FDemoCoroutinesChannelResult&count_bg=%2379C83D&title_bg=%23555555&icon=&icon_color=%23E7E7E7&title=hits&edge_flat=false)](https://hits.seeyoufarm.com)
@@ -8,3 +10,83 @@
     <img src="demo.gif" height="480"/>
 </p>
 
+## Overview
+
+### 1. Create `MainSingleEvent` class.
+
+```kotlin
+sealed interface MainSingleEvent<out T : MainSingleEvent<T>> {
+  interface Key<out T : MainSingleEvent<T>>
+
+  val key: Key<T>
+
+  data class HomeFragmentResult(val text: String) : MainSingleEvent<HomeFragmentResult> {
+    override val key = HomeFragmentResult
+
+    companion object : Key<HomeFragmentResult>
+  }
+
+  data class DashboardFragmentResult(val text: String) : MainSingleEvent<DashboardFragmentResult> {
+    override val key = DashboardFragmentResult
+
+    companion object : Key<DashboardFragmentResult>
+  }
+
+  data class HomeDetailsResult(val text: String) : MainSingleEvent<HomeDetailsResult> {
+    override val key = HomeDetailsResult
+
+    companion object : Key<HomeDetailsResult>
+  }
+
+  companion object {
+    val KEYS: Set<Key<SomeMainSingleEvent>> = setOf(
+      HomeFragmentResult,
+      DashboardFragmentResult,
+      HomeDetailsResult,
+    )
+  }
+}
+```
+
+### 2. Create `MainVM` class with buffered channels as event bus.
+
+```kotlin
+class MainVM : ViewModel() {
+  private val eventChannels: Map<MainSingleEvent.Key<SomeMainSingleEvent>, Channel<SomeMainSingleEvent>> =
+    MainSingleEvent.KEYS.associateBy(
+      keySelector = { it },
+      valueTransform = { Channel<MainSingleEvent<SomeMainSingleEvent>>(Channel.UNLIMITED) }
+    )
+
+  fun <T : MainSingleEvent<T>> sendEvent(event: T) {
+    checkNotNull(eventChannels[event.key]) { "Must register ${event.key} in MainSingleEvent.Companion.KEYS before using!" }
+      .trySend(event)
+      .getOrThrow()
+      .also { Log.d("@@@", "Sent $event") }
+  }
+
+  @Suppress("UNCHECKED_CAST")
+  fun <T : MainSingleEvent<T>, K : MainSingleEvent.Key<T>> receiveEventFlow(key: K): Flow<T> =
+    checkNotNull(eventChannels[key]) { "Must register $key in MainSingleEvent.Companion.KEYS before using!" }
+      .receiveAsFlow()
+      .map { it as T }
+}
+```
+
+### 3. Send and receive events in `Fragment`s.
+
+We will share `MainVM` instance between `Fragment`s using `Activity` as owner.
+
+```kotlin
+private val mainVM by viewModels<MainVM>(
+  ownerProducer = { requireActivity() }
+)
+
+// send in HomeFragment
+mainVM.sendEvent(MainSingleEvent.HomeFragmentResult("Hello from HomeFragment"))
+
+// receive in others
+mainVM.receiveEventFlow(MainSingleEvent.HomeFragmentResult)
+  .onEach { Log.d("###", "Received $it") }
+  .launchIn(lifecycleScope)
+```