From f74bd5e1d9e133f578993b8c6c5ac6fcfd798e53 Mon Sep 17 00:00:00 2001
From: PsiOmegaDelta <git@psiomega.se>
Date: Sat, 12 Dec 2015 12:05:57 +0100
Subject: [PATCH] Observer fixups.

Adds a proper proc for raising events.
Now only creates the observer lists when an object registers itself.
Multitools now unregister themselves properly from buffers on Destroy().
---
 .../observer_listener/datum/observer.dm       | 32 ++++++++++++-------
 code/game/objects/items/devices/multitool.dm  | 14 +++++---
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/code/controllers/observer_listener/datum/observer.dm b/code/controllers/observer_listener/datum/observer.dm
index cc0ef0612a3..e6cca2049ce 100644
--- a/code/controllers/observer_listener/datum/observer.dm
+++ b/code/controllers/observer_listener/datum/observer.dm
@@ -4,28 +4,38 @@
 	var/list/observer_events
 
 /datum/Destroy()
-	var/list/destroy_listeners = get_listener_list_from_event(OBSERVER_EVENT_DESTROY)
-	if(destroy_listeners)
-		for(var/destroy_listener in destroy_listeners)
-			call(destroy_listener, destroy_listeners[destroy_listener])(src)
-
+	raise_event(OBSERVER_EVENT_DESTROY, list(src))
 	for(var/list/listeners in observer_events)
 		listeners.Cut()
 
 	return ..()
 
 /datum/proc/register(var/event, var/procOwner, var/proc_call)
-	var/list/listeners = get_listener_list_from_event(event)
+	var/list/listeners = get_listener_list_from_event(event, TRUE)
 	listeners[procOwner] = proc_call
 
 /datum/proc/unregister(var/event, var/procOwner)
-	var/list/listeners = get_listener_list_from_event(event)
+	var/list/listeners = get_listener_list_from_event(event, FALSE)
 	listeners -= procOwner
 
-/datum/proc/get_listener_list_from_event(var/observer_event)
-	if(!observer_events) observer_events = list()
+/datum/proc/raise_event(var/event, var/list/args = list())
+	var/list/listeners = get_listener_list_from_event(event, FALSE)
+	if(listeners)
+		for(var/listener in listeners)
+			call(listener, listeners[listener])(arglist(args))
+
+/datum/proc/get_listener_list_from_event(var/observer_event, var/create_list)
+	if(!observer_events)
+		if(create_list)
+			observer_events = list()
+		else
+			return
+
 	var/list/listeners = observer_events[observer_event]
 	if(!listeners)
-		listeners = list()
-		observer_events[observer_event] = listeners
+		if(create_list)
+			listeners = list()
+			observer_events[observer_event] = listeners
+		else
+			return
 	return listeners
diff --git a/code/game/objects/items/devices/multitool.dm b/code/game/objects/items/devices/multitool.dm
index a804041694a..cc47b871661 100644
--- a/code/game/objects/items/devices/multitool.dm
+++ b/code/game/objects/items/devices/multitool.dm
@@ -23,6 +23,10 @@
 	var/buffer_name
 	var/atom/buffer_object
 
+/obj/item/device/multitool/Destroy()
+	unregister_buffer(buffer_object)
+	return ..()
+
 /obj/item/device/multitool/proc/get_buffer(var/typepath)
 	// Only allow clearing the buffer name when someone fetches the buffer.
 	// Means you cannot be sure the source hasn't been destroyed until the very moment it's needed.
@@ -41,16 +45,16 @@
 	if(!buffer || istype(buffer))
 		buffer_name = buffer ? buffer.name : null
 		if(buffer != buffer_object)
-			if(buffer_object)
-				buffer_object.unregister(OBSERVER_EVENT_DESTROY, src)
+			unregister_buffer(buffer_object)
 			buffer_object = buffer
 			if(buffer_object)
-				buffer_object.register(OBSERVER_EVENT_DESTROY, src, /obj/item/device/multitool/proc/on_buffer_destroyed)
+				buffer_object.register(OBSERVER_EVENT_DESTROY, src, /obj/item/device/multitool/proc/unregister_buffer)
 
-/obj/item/device/multitool/proc/on_buffer_destroyed(var/atom/destroyed_buffer)
+/obj/item/device/multitool/proc/unregister_buffer(var/atom/buffer_to_unregister)
 	// Only remove the buffered object, don't reset the name
 	// This means one cannot know if the buffer has been destroyed until one attempts to use it.
-	if(destroyed_buffer == buffer_object)
+	if(buffer_to_unregister == buffer_object && buffer_object)
+		buffer_object.unregister(OBSERVER_EVENT_DESTROY, src)
 		buffer_object = null
 
 /obj/item/device/multitool/resolve_attackby(atom/A, mob/user)