Make broadcaster generic

event/event.go

@@ -9,46 +9,55 @@ type Cookie interface {
 	Close ()
 }
 
-// Broadcaster manages event listeners
-type Broadcaster struct {
+// Broadcaster manages event listeners.
+type Broadcaster[L any] struct {
 	lastID    int
-	listeners map[int] func ()
+	listeners map[int] L
 }
 
 // Connect adds a new listener to the broadcaster and returns a corresponding
 // cookie.
-func (broadcaster *Broadcaster) Connect (listener func ()) Cookie {
-	if listener == nil { return nil }
-
-	if broadcaster.listeners == nil {
-		broadcaster.listeners = make(map[int] func ())
-	}
+func (broadcaster *Broadcaster[L]) Connect (listener L) Cookie {
+	broadcaster.ensure()
 	
 	cookie := broadcaster.newCookie()
 	broadcaster.listeners[cookie.id] = listener
 	return cookie
 }
 
-// Broadcast runs all event listeners at once.
-func (broadcaster *Broadcaster)  Broadcast () {
-	for _, listener := range broadcaster.listeners {
-		listener()
-	}
+// Listeners returns a map of all connected listeners.
+func (broadcaster *Broadcaster[L]) Listeners () map[int] L {
+	broadcaster.ensure()
+	return broadcaster.listeners
 }
 
-func (broadcaster *Broadcaster) newCookie () cookie {
+func (broadcaster *Broadcaster[L]) newCookie () cookie[L] {
 	broadcaster.lastID ++
-	return cookie {
+	return cookie[L] {
 		id:          broadcaster.lastID,
 		broadcaster: broadcaster,
 	}
 }
 
-type cookie struct {
-	id int
-	broadcaster *Broadcaster
+func (broadcaster *Broadcaster[L]) ensure () {
+	if broadcaster.listeners == nil {
+		broadcaster.listeners = make(map[int] L)
+	}
 }
 
-func (cookie cookie) Close () {
+type cookie[L any] struct {
+	id int
+	broadcaster *Broadcaster[L]
+}
+
+func (cookie cookie[L]) Close () {
 	delete(cookie.broadcaster.listeners, cookie.id)
 }
+
+// FuncBroadcaster is a broadcaster that manages functions with no arguments.
+type FuncBroadcaster Broadcaster[func ()]
+
+// Broadcast calls all connected listener funcs.
+func (broadcaster *FuncBroadcaster) Broadcast () {
+	
+}