Implements UIDs and initial topic integration

code/__HELPERS/unique_ids.dm

@@ -0,0 +1,46 @@
+// Unique Datum Identifiers
+
+// Basically, a replacement for plain \refs that ensure the reference still
+// points to the exact same datum/client, but doesn't prevent GC like tags do.
+
+// Turns this:
+//   var/myref = "\ref[mydatum]"
+//   var/datum/D = locate(myref)
+// into this:
+//   var/myUID = mydatum.UID()
+//   var/datum/D = locateUID(myUID)
+
+var/global/next_unique_datum_id = 1
+
+/datum/var/tmp/unique_datum_id = null
+/client/var/tmp/unique_datum_id = null
+
+/datum/proc/UID()
+	if(!unique_datum_id)
+		var/tag_backup = tag
+		tag = null // Grab the raw ref, not the tag
+		unique_datum_id = "\ref[src]_[next_unique_datum_id++]"
+		tag = tag_backup
+	return unique_datum_id
+
+/client/proc/UID()
+	if(!unique_datum_id)
+		unique_datum_id = "\ref[src]_[next_unique_datum_id++]"
+	return unique_datum_id
+
+/proc/locateUID(uid)
+	if(!istext(uid))
+		return null
+
+	var/splitat = findlasttext(uid, "_")
+
+	if(!splitat)
+		return null
+
+	var/datum/D = locate(copytext(uid, 1, splitat))
+
+	// We might locate a client instead of a datum, but just using : is easier
+	// than actually checking and typecasting
+	if(D && D:unique_datum_id == uid)
+		return D
+	return null

code/modules/client/client procs.dm

@@ -29,6 +29,15 @@
 	if(!usr || usr != mob)	//stops us calling Topic for somebody else's client. Also helps prevent usr=null
 		return
 
+	// src should always be a UID; if it isn't, warn instead of failing entirely
+	if(href_list["src"])
+		hsrc = locateUID(href_list["src"])
+		if(!hsrc)
+			hsrc = locate(href_list["src"])
+			if(hsrc)
+				var/hsrc_info = datum_info_line(hsrc) || "[hsrc]"
+				log_runtime(EXCEPTION("Got \\ref-based src in topic from [src] for [hsrc_info], should be UID: [href]"))
+
 	#if defined(TOPIC_DEBUGGING)
 	to_chat(world, "[src]'s Topic: [href] destined for [hsrc].")
 	#endif