=act #3572 Add parens to sender

* because it is not referentially transparent; normally we reserved parens for
  side-effecting code but given how people thoughtlessly close over it we revised
  that that decision for sender
* caller can still omit parens

akka-docs/rst/scala/actors.rst

@@ -432,7 +432,7 @@ Messages can be sent via the :class:`ActorSelection` and the path of the
 does not match any actors the message will be dropped.
 
 To acquire an :class:`ActorRef` for an :class:`ActorSelection` you need to send
-a message to the selection and use the ``sender`` reference of the reply from
+a message to the selection and use the ``sender()`` reference of the reply from
 the actor. There is a built-in ``Identify`` message that all Actors will
 understand and automatically reply to with a ``ActorIdentity`` message
 containing the :class:`ActorRef`. This message is handled specially by the
@@ -517,8 +517,8 @@ message. This gives the best concurrency and scalability characteristics.
 
 If invoked from within an Actor, then the sending actor reference will be
 implicitly passed along with the message and available to the receiving Actor
-in its ``sender: ActorRef`` member field. The target actor can use this
-to reply to the original sender, by using ``sender ! replyMsg``.
+in its ``sender(): ActorRef`` member method. The target actor can use this
+to reply to the original sender, by using ``sender() ! replyMsg``.
 
 If invoked from an instance that is **not** an Actor the sender will be
 :obj:`deadLetters` actor reference by default.
@@ -540,7 +540,7 @@ future to affect the submission of the aggregated :class:`Result` to another
 actor.
 
 Using ``ask`` will send a message to the receiving Actor as with ``tell``, and
-the receiving actor must reply with ``sender ! reply`` in order to complete the
+the receiving actor must reply with ``sender() ! reply`` in order to complete the
 returned :class:`Future` with a value. The ``ask`` operation involves creating
 an internal actor for handling this reply, which needs to have a timeout after
 which it is destroyed in order not to leak resources; see more below.
@@ -613,8 +613,8 @@ Reply to messages
 =================
 
 If you want to have a handle for replying to a message, you can use
-``sender``, which gives you an ActorRef. You can reply by sending to
-that ActorRef with ``sender ! replyMsg``. You can also store the ActorRef
+``sender()``, which gives you an ActorRef. You can reply by sending to
+that ActorRef with ``sender() ! replyMsg``. You can also store the ActorRef
 for replying later, or passing on to other actors. If there is no sender (a
 message was sent without an actor or future context) then the sender
 defaults to a 'dead-letter' actor ref.
@@ -623,7 +623,7 @@ defaults to a 'dead-letter' actor ref.
 
   case request =>
     val result = process(request)
-    sender ! result       // will have dead-letter actor as default
+    sender() ! result       // will have dead-letter actor as default
 
 Receive timeout
 ===============

akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala

@@ -40,7 +40,7 @@ class FirstActor extends Actor {
   val child = context.actorOf(Props[MyActor], name = "myChild")
   //#plus-some-behavior
   def receive = {
-    case x => sender ! x
+    case x => sender() ! x
   }
   //#plus-some-behavior
 }
@@ -64,7 +64,7 @@ class DemoActorWrapper extends Actor {
 
   class DemoActor(magicNumber: Int) extends Actor {
     def receive = {
-      case x: Int => sender ! (x + magicNumber)
+      case x: Int => sender() ! (x + magicNumber)
     }
   }
 
@@ -91,7 +91,7 @@ class AnonymousActor extends Actor {
         def receive = {
           case DoIt(msg) =>
             val replyMsg = doSomeDangerousWork(msg)
-            sender ! replyMsg
+            sender() ! replyMsg
             context.stop(self)
         }
         def doSomeDangerousWork(msg: ImmutableMessage): String = { "done" }
@@ -123,10 +123,10 @@ class ReplyException extends Actor {
       //#reply-exception
       try {
         val result = operation()
-        sender ! result
+        sender() ! result
       } catch {
         case e: Exception =>
-          sender ! akka.actor.Status.Failure(e)
+          sender() ! akka.actor.Status.Failure(e)
           throw e
       }
     //#reply-exception
@@ -271,7 +271,7 @@ class ActorDocSpec extends AkkaSpec(Map("akka.loglevel" -> "INFO")) {
   "creating actor with IndirectActorProducer" in {
     class Echo(name: String) extends Actor {
       def receive = {
-        case n: Int => sender ! name
+        case n: Int => sender() ! name
         case message =>
           val target = testActor
           //#forward
@@ -365,12 +365,12 @@ class ActorDocSpec extends AkkaSpec(Map("akka.loglevel" -> "INFO")) {
   class HotSwapActor extends Actor {
     import context._
     def angry: Receive = {
-      case "foo" => sender ! "I am already angry?"
+      case "foo" => sender() ! "I am already angry?"
       case "bar" => become(happy)
     }
 
     def happy: Receive = {
-      case "bar" => sender ! "I am already happy :-)"
+      case "bar" => sender() ! "I am already happy :-)"
       case "foo" => become(angry)
     }
 
@@ -417,7 +417,7 @@ class ActorDocSpec extends AkkaSpec(Map("akka.loglevel" -> "INFO")) {
 
         def receive = {
           case "kill" =>
-            context.stop(child); lastSender = sender
+            context.stop(child); lastSender = sender()
           case Terminated(`child`) => lastSender ! "finished"
         }
       }
@@ -522,12 +522,12 @@ class ActorDocSpec extends AkkaSpec(Map("akka.loglevel" -> "INFO")) {
     def receive = {
       case ref: ActorRef =>
         //#reply-with-sender
-        sender.tell("reply", context.parent) // replies will go back to parent
-        sender.!("reply")(context.parent) // alternative syntax (beware of the parens!)
+        sender().tell("reply", context.parent) // replies will go back to parent
+        sender().!("reply")(context.parent) // alternative syntax (beware of the parens!)
       //#reply-with-sender
       case x =>
         //#reply-without-sender
-        sender ! x // replies will go to this actor
+        sender() ! x // replies will go to this actor
       //#reply-without-sender
     }
   }
@@ -585,13 +585,13 @@ class ActorDocSpec extends AkkaSpec(Map("akka.loglevel" -> "INFO")) {
 
   trait TheirComposableActor extends ComposableActor {
     receiveBuilder += {
-      case "foo" => sender ! "foo received"
+      case "foo" => sender() ! "foo received"
     }
   }
 
   class MyComposableActor extends TheirComposableActor {
     receiveBuilder += {
-      case "bar" => sender ! "bar received"
+      case "bar" => sender() ! "bar received"
     }
   }
   //#receive-orElse2

akka-docs/rst/scala/code/docs/actor/FaultHandlingDocSample.scala

@@ -204,7 +204,7 @@ class CounterService extends Actor {
         if (backlog.size >= MaxBacklog)
           throw new ServiceUnavailable(
             "CounterService not available, lack of initial value")
-        backlog :+= (sender -> msg)
+        backlog :+= (sender() -> msg)
     }
   }
 
@@ -239,7 +239,7 @@ class Counter(key: String, initialValue: Long) extends Actor {
       storeCount()
 
     case GetCurrentCount =>
-      sender ! CurrentCount(key, count)
+      sender() ! CurrentCount(key, count)
 
   }
 
@@ -272,7 +272,7 @@ class Storage extends Actor {
 
   def receive = LoggingReceive {
     case Store(Entry(key, count)) => db.save(key, count)
-    case Get(key)                 => sender ! Entry(key, db.load(key).getOrElse(0L))
+    case Get(key)                 => sender() ! Entry(key, db.load(key).getOrElse(0L))
   }
 }
 

akka-docs/rst/scala/code/docs/actor/FaultHandlingDocSpec.scala

@@ -34,7 +34,7 @@ object FaultHandlingDocSpec {
     //#strategy
 
     def receive = {
-      case p: Props => sender ! context.actorOf(p)
+      case p: Props => sender() ! context.actorOf(p)
     }
   }
   //#supervisor
@@ -56,7 +56,7 @@ object FaultHandlingDocSpec {
     //#strategy2
 
     def receive = {
-      case p: Props => sender ! context.actorOf(p)
+      case p: Props => sender() ! context.actorOf(p)
     }
     // override default to kill all children during restart
     override def preRestart(cause: Throwable, msg: Option[Any]) {}
@@ -87,7 +87,7 @@ object FaultHandlingDocSpec {
     def receive = {
       case ex: Exception => throw ex
       case x: Int        => state = x
-      case "get"         => sender ! state
+      case "get"         => sender() ! state
     }
   }
   //#child

akka-docs/rst/scala/code/docs/actor/InitializationDocSpec.scala

@@ -44,7 +44,7 @@ object InitializationDocSpec {
     }
 
     def initialized: Receive = {
-      case "U OK?" => initializeMe foreach { sender ! _ }
+      case "U OK?" => initializeMe foreach { sender() ! _ }
     }
     //#messageInit
 

akka-docs/rst/scala/code/docs/camel/Consumers.scala

@@ -28,7 +28,7 @@ object Consumers {
       def endpointUri = "jetty:http://localhost:8877/camel/default"
 
       def receive = {
-        case msg: CamelMessage => sender ! ("Hello %s" format msg.bodyAs[String])
+        case msg: CamelMessage => sender() ! ("Hello %s" format msg.bodyAs[String])
       }
     }
     //#Consumer2
@@ -46,12 +46,12 @@ object Consumers {
 
       def receive = {
         case msg: CamelMessage =>
-          sender ! Ack
+          sender() ! Ack
           // on success
           // ..
           val someException = new Exception("e1")
           // on failure
-          sender ! Failure(someException)
+          sender() ! Failure(someException)
       }
     }
     //#Consumer3
@@ -65,7 +65,7 @@ object Consumers {
       def endpointUri = "jetty:http://localhost:8877/camel/default"
       override def replyTimeout = 500 millis
       def receive = {
-        case msg: CamelMessage => sender ! ("Hello %s" format msg.bodyAs[String])
+        case msg: CamelMessage => sender() ! ("Hello %s" format msg.bodyAs[String])
       }
     }
     //#Consumer4

akka-docs/rst/scala/code/docs/camel/CustomRoute.scala

@@ -19,7 +19,7 @@ object CustomRoute {
     class Responder extends Actor {
       def receive = {
         case msg: CamelMessage =>
-          sender ! (msg.mapBody {
+          sender() ! (msg.mapBody {
             body: String => "received %s" format body
           })
       }
@@ -53,7 +53,7 @@ object CustomRoute {
         handled(true).transform(Builder.exceptionMessage).end
 
       final override def preRestart(reason: Throwable, message: Option[Any]) {
-        sender ! Failure(reason)
+        sender() ! Failure(reason)
       }
     }
     //#ErrorThrowingConsumer

akka-docs/rst/scala/code/docs/camel/Producers.scala

@@ -120,7 +120,7 @@ object Producers {
       def receive = {
         case msg =>
           val template = CamelExtension(context.system).template
-          sender ! template.requestBody("direct:news", msg)
+          sender() ! template.requestBody("direct:news", msg)
       }
     }
     //#RequestProducerTemplate

akka-docs/rst/scala/code/docs/camel/PublishSubscribe.scala

@@ -27,7 +27,7 @@ object PublishSubscribe {
     def receive = {
       case msg: CamelMessage => {
         publisher ! msg.bodyAs[String]
-        sender ! ("message published")
+        sender() ! ("message published")
       }
     }
   }

akka-docs/rst/scala/code/docs/event/LoggingDocSpec.scala

@@ -85,7 +85,7 @@ object LoggingDocSpec {
 
   class MyEventListener extends Actor {
     def receive = {
-      case InitializeLogger(_)                        => sender ! LoggerInitialized
+      case InitializeLogger(_)                        => sender() ! LoggerInitialized
       case Error(cause, logSource, logClass, message) => // ...
       case Warning(logSource, logClass, message)      => // ...
       case Info(logSource, logClass, message)         => // ...

akka-docs/rst/scala/code/docs/future/FutureDocSpec.scala

@@ -18,9 +18,9 @@ object FutureDocSpec {
 
   class MyActor extends Actor {
     def receive = {
-      case x: String       => sender ! x.toUpperCase
-      case x: Int if x < 0 => sender ! Status.Failure(new ArithmeticException("Negative values not supported"))
-      case x: Int          => sender ! x
+      case x: String       => sender() ! x.toUpperCase
+      case x: Int if x < 0 => sender() ! Status.Failure(new ArithmeticException("Negative values not supported"))
+      case x: Int          => sender() ! x
     }
   }
 
@@ -30,7 +30,7 @@ object FutureDocSpec {
     var n = 1
     def receive = {
       case GetNext =>
-        sender ! n
+        sender() ! n
         n += 2
     }
   }

akka-docs/rst/scala/code/docs/io/EchoServer.scala

@@ -63,8 +63,8 @@ class EchoManager(handlerClass: Class[_]) extends Actor with ActorLogging {
     //#echo-manager
     case Connected(remote, local) =>
       log.info("received connection from {}", remote)
-      val handler = context.actorOf(Props(handlerClass, sender, remote))
-      sender ! Register(handler, keepOpenOnPeerClosed = true)
+      val handler = context.actorOf(Props(handlerClass, sender(), remote))
+      sender() ! Register(handler, keepOpenOnPeerClosed = true)
     //#echo-manager
   }
 

akka-docs/rst/scala/code/docs/io/IODocSpec.scala

@@ -46,7 +46,7 @@ class Server extends Actor {
       context.parent ! c
       //#server
       val handler = context.actorOf(Props[SimplisticHandler])
-      val connection = sender
+      val connection = sender()
       connection ! Register(handler)
   }
 
@@ -57,7 +57,7 @@ class Server extends Actor {
 class SimplisticHandler extends Actor {
   import Tcp._
   def receive = {
-    case Received(data) => sender ! Write(data)
+    case Received(data) => sender() ! Write(data)
     case PeerClosed     => context stop self
   }
 }
@@ -83,7 +83,7 @@ class Client(remote: InetSocketAddress, listener: ActorRef) extends Actor {
 
     case c @ Connected(remote, local) =>
       listener ! c
-      val connection = sender
+      val connection = sender()
       connection ! Register(self)
       context become {
         case data: ByteString =>

akka-docs/rst/scala/code/docs/io/UdpDocSpec.scala

@@ -22,9 +22,9 @@ object ScalaUdpDocSpec {
 
     def receive = {
       case Udp.SimpleSenderReady =>
-        context.become(ready(sender))
+        context.become(ready(sender()))
         //#sender
-        sender ! Udp.Send(ByteString("hello"), remote)
+        sender() ! Udp.Send(ByteString("hello"), remote)
       //#sender
     }
 
@@ -48,7 +48,7 @@ object ScalaUdpDocSpec {
         //#listener
         nextActor forward local
         //#listener
-        context.become(ready(sender))
+        context.become(ready(sender()))
     }
 
     def ready(socket: ActorRef): Receive = {
@@ -72,9 +72,9 @@ object ScalaUdpDocSpec {
 
     def receive = {
       case UdpConnected.Connected =>
-        context.become(ready(sender))
+        context.become(ready(sender()))
         //#connected
-        sender ! UdpConnected.Send(ByteString("hello"))
+        sender() ! UdpConnected.Send(ByteString("hello"))
       //#connected
     }
 

akka-docs/rst/scala/code/docs/remoting/RemoteDeploymentDocSpec.scala

@@ -13,7 +13,7 @@ import akka.remote.RemoteScope
 object RemoteDeploymentDocSpec {
 
   class SampleActor extends Actor {
-    def receive = { case _ => sender ! self }
+    def receive = { case _ => sender() ! self }
   }
 
 }

akka-docs/rst/scala/code/docs/routing/ConsistentHashingRouterDocSpec.scala

@@ -19,7 +19,7 @@ object ConsistentHashingRouterDocSpec {
 
     def receive = {
       case Entry(key, value) => cache += (key -> value)
-      case Get(key)          => sender ! cache.get(key)
+      case Get(key)          => sender() ! cache.get(key)
       case Evict(key)        => cache -= key
     }
   }

akka-docs/rst/scala/code/docs/routing/CustomRouterDocSpec.scala

@@ -58,7 +58,7 @@ akka.actor.deployment {
 
   class Storage extends Actor {
     def receive = {
-      case x => sender ! x
+      case x => sender() ! x
     }
   }
 

akka-docs/rst/scala/code/docs/routing/RouterDocSpec.scala

@@ -197,7 +197,7 @@ router-dispatcher {}
 
     def receive = {
       case w: Work =>
-        router.route(w, sender)
+        router.route(w, sender())
       case Terminated(a) =>
         router = router.removeRoutee(a)
         val r = context.actorOf(Props[Worker])
@@ -375,7 +375,7 @@ router-dispatcher {}
 
   class Echo extends Actor {
     def receive = {
-      case m => sender ! m
+      case m => sender() ! m
     }
   }
 }

akka-docs/rst/scala/code/docs/testkit/PlainWordSpec.scala

@@ -16,7 +16,7 @@ import akka.testkit.ImplicitSender
 object MySpec {
   class EchoActor extends Actor {
     def receive = {
-      case x => sender ! x
+      case x => sender() ! x
     }
   }
 }

akka-docs/rst/scala/code/docs/testkit/TestKitUsageSpec.scala

@@ -117,7 +117,7 @@ object TestKitUsageSpec {
    */
   class EchoActor extends Actor {
     def receive = {
-      case msg => sender ! msg
+      case msg => sender() ! msg
     }
   }
 

akka-docs/rst/scala/code/docs/testkit/TestkitDocSpec.scala

@@ -22,8 +22,8 @@ object TestkitDocSpec {
 
   class MyActor extends Actor {
     def receive = {
-      case Say42       => sender ! 42
-      case "some work" => sender ! "some result"
+      case Say42       => sender() ! 42
+      case "some work" => sender() ! "some result"
     }
   }
 
@@ -201,7 +201,7 @@ class TestkitDocSpec extends AkkaSpec with DefaultTimeout with ImplicitSender {
         expectMsgPF() {
           case Update(id, _) if id == x => true
         }
-        sender ! "ACK"
+        sender() ! "ACK"
       }
     }
     //#test-special-probe

akka-docs/rst/scala/scheduler.rst

@@ -39,7 +39,7 @@ Some examples
 
     If you schedule functions or Runnable instances you should be extra careful
     to not close over unstable references. In practice this means not using ``this``
-    inside the closure in the scope of an Actor instance, not accessing ``sender`` directly
+    inside the closure in the scope of an Actor instance, not accessing ``sender()`` directly
     and not calling the methods of the Actor instance directly. If you need to
     schedule an invocation schedule a message to ``self`` instead (containing the
     necessary parameters) and then call the method when the message is received.