=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/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