feat: westworldwithmessaging. add entitymanager, telegram, messagehandlers, delayedmessages, expand baseentity

chapter-2-state-driven-agent-design/westworldwithmessaging/entity.go

@@ -1,15 +1,21 @@
-package westworldwithwoman
+package westworldwithmessaging
 
 // Entity is what every game object in the world must be able to do.
-// The C++ code used a pure virtual function (Update()=0) to force
-// every subclass to write its own Update. Go has no subclasses, so
-// instead we say: "anything with an Update() and an ID() method
-// counts as an Entity." A type only satisfies this interface once
-// it has its own Update method - just like the C++ version couldn't
-// be used until Update was implemented.
+// The C++ code used pure virtual functions (Update()=0, and now
+// HandleMessage()=0) to force every subclass to write its own
+// versions. Go has no subclasses, so instead we say: "anything with
+// Update(), ID() and HandleMessage() methods counts as an Entity." A
+// type only satisfies this interface once it has all three - just
+// like the C++ version couldn't be used until both were implemented.
 type Entity interface {
 	Update()
 	ID() int
+
+	// HandleMessage lets an entity respond to a Telegram sent to it
+	// by the message dispatcher. It returns true if the message was
+	// actually handled, false otherwise - callers use that to decide
+	// whether to try routing the message somewhere else instead.
+	HandleMessage(msg Telegram) bool
 }
 
 // nextValidID plays the role of the C++ "static int m_iNextValidID".