feat: streamlined approach for Behaviors #1444

actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/BehaviorSpec.scala

@@ -378,6 +378,22 @@ class ReceiveBehaviorSpec extends Messages with BecomeWithLifecycle with Stoppab
   }
 }
 
+class ReceiveMessageWithSameBehaviorSpec extends Messages {
+  override def behavior(monitor: ActorRef[Event]): (Behavior[Command], Aux) = behv(monitor) -> null
+  private def behv(monitor: ActorRef[Event]): Behavior[Command] = {
+    SBehaviors
+      .receiveMessageWithSame[Command] {
+        case Miss =>
+          monitor ! Missed
+        case Ignore =>
+          monitor ! Ignored
+        case Ping =>
+          monitor ! Pong
+        case _ =>
+      }
+  }
+}
+
 class ImmutableWithSignalScalaBehaviorSpec extends Messages with BecomeWithLifecycle with Stoppable {
 
   override def behavior(monitor: ActorRef[Event]): (Behavior[Command], Aux) = behv(monitor) -> null

actor-typed/src/main/scala/org/apache/pekko/actor/typed/javadsl/Behaviors.scala

@@ -143,6 +143,29 @@ object Behaviors {
   def receiveMessage[T](onMessage: pekko.japi.Function[T, Behavior[T]]): Behavior[T] =
     new BehaviorImpl.ReceiveBehavior((_, msg) => onMessage.apply(msg))
 
+  /**
+   * Simplified version of [[receiveMessage]] with only a single argument - the message
+   * to be handled, but it doesn't produce a return value of next behavior.
+   * Useful for when the behavior doesn't want to change in runtime.
+   *
+   * Construct an actor behavior that can react to incoming messages but not to
+   * lifecycle signals. After spawning this actor from another actor (or as the
+   * guardian of an [[pekko.actor.typed.ActorSystem]]) it will be executed within an
+   * [[ActorContext]] that allows access to the system, spawning and watching
+   * other actors, etc.
+   *
+   * Compared to using [[AbstractBehavior]] this factory is a more functional style
+   * of defining the `Behavior`. Processing the next message will not result in
+   * different behavior than this one
+   *
+   * @since 1.1.0
+   */
+  def receiveMessageWithSame[T](onMessage: pekko.japi.Procedure[T]): Behavior[T] =
+    new BehaviorImpl.ReceiveBehavior((_, msg) => {
+      onMessage.apply(msg)
+      same[T]
+    })
+
   /**
    * Construct an actor behavior that can react to both incoming messages and
    * lifecycle signals. After spawning this actor from another actor (or as the

actor-typed/src/main/scala/org/apache/pekko/actor/typed/scaladsl/Behaviors.scala

@@ -133,6 +133,27 @@ object Behaviors {
   def receiveMessage[T](onMessage: T => Behavior[T]): Receive[T] =
     new ReceiveMessageImpl(onMessage)
 
+  /**
+   * Simplified version of [[receiveMessage]] with only a single argument - the message
+   * to be handled, but it doesn't produce a return value of next behavior.
+   * Useful for when the behavior doesn't want to change in runtime.
+   *
+   * Construct an actor behavior that can react to incoming messages but not to
+   * lifecycle signals. After spawning this actor from another actor (or as the
+   * guardian of an [[pekko.actor.typed.ActorSystem]]) it will be executed within an
+   * [[ActorContext]] that allows access to the system, spawning and watching
+   * other actors, etc.
+   *
+   * Compared to using [[AbstractBehavior]] this factory is a more functional style
+   * of defining the `Behavior`. Processing the next message will not result in
+   * different behavior than this one
+   *
+   * @since 1.1.0
+   */
+  def receiveMessageWithSame[T](onMessage: T => Unit): Receive[T] = {
+    new ReceiveMessageImpl(onMessage.andThen(_ => same))
+  }
+
   /**
    * Construct an actor `Behavior` from a partial message handler which treats undefined messages as unhandled.
    */