UI: Enable deferred loading of the Options UI

Currently, the module is either loaded (settings are registered) or not (settings not registered = menu entry missing).

With this change, the AceConfig registry setup is moved into the addon core. Ace will then be able to register the settings properly, even if the options aren't yet loaded. This not only fixes the glitch that had users confused, but also improves the "perceived" snappiness of opening the UI because most of the time is spent in Blizzard's menu code.

This cost is already paid if the UI has been opened before, whereas loading the options, registering the settings tree, then creating it, and THEN opening it leads to a noticeable delay (which is likely to be blamed on Rarity, even though it's just slow Lua-C-API calls in the client's native code).

Author: rdw-software

Core.lua

@@ -111,6 +111,7 @@ local IsSpellKnown = _G.IsSpellKnown
 local CombatLogGetCurrentEventInfo = _G.CombatLogGetCurrentEventInfo
 local IsQuestFlaggedCompleted = _G.C_QuestLog.IsQuestFlaggedCompleted
 local C_Covenants = _G.C_Covenants
+local LoadAddOn = _G.C_AddOns.LoadAddOn
 
 local COMBATLOG_OBJECT_AFFILIATION_MINE = _G.COMBATLOG_OBJECT_AFFILIATION_MINE
 local COMBATLOG_OBJECT_AFFILIATION_PARTY = _G.COMBATLOG_OBJECT_AFFILIATION_PARTY
@@ -147,6 +148,22 @@ do
 
 	function R:OnEnable()
 		self:DoEnable()
+		-- The Options module is disabled to reduce memory usage and loading time
+		-- However, players can only see the menu entry once AceConfig has registered it
+		-- Workaround: Provide a generator (function) that creates the UI only when needed
+		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity", function()
+			return R:LazyLoadOptions("options")
+		end)
+		R.optionsFrame = LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity", "Rarity")
+		R.profileOptions = LibStub("AceDBOptions-3.0"):GetOptionsTable(R.db)
+		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity-Profiles", R.profileOptions)
+		R.profileFrame = LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity-Profiles", "Profiles", "Rarity")
+
+		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity-Advanced", function()
+			return R:LazyLoadOptions("advancedSettings")
+		end)
+		R.advancedSettingsFrame =
+			LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity-Advanced", "Advanced", "Rarity")
 	end
 
 	function R:DoEnable()
@@ -330,6 +347,20 @@ do
 	end
 end
 
+function Rarity:LazyLoadOptions(which)
+	local options = R[which]
+	if type(options) == "table" then
+		-- This UI tree was previously generated (fast path; upfront cost already paid)
+		return options
+	end
+
+	Rarity.Profiling:StartTimer("RarityOptions: LoadAddon")
+	LoadAddOn("Rarity_Options")
+	Rarity.Profiling:EndTimer("RarityOptions: LoadAddon")
+
+	return R[which]
+end
+
 function R:DelayedInit()
 	self:ScanStatistics("DELAYED INIT")
 	self:ScanCalendar("DELAYED INIT")

Core/EventHandlers.lua

@@ -744,9 +744,11 @@ function R:OnChatCommand(input)
 	elseif strlower(input) == "tinspect" then --  TODO Document it?
 		Rarity.Profiling:InspectAccumulatedTimes()
 	else
-		LoadAddOn("Rarity_Options")
-		if R.optionsFrame then
+		Rarity:LazyLoadOptions()
+		if R.options then
+			Rarity.Profiling:StartTimer("RarityOptions: OpenToCategory")
 			Settings.OpenToCategory("Rarity")
+			Rarity.Profiling:EndTimer("RarityOptions: OpenToCategory")
 		else
 			self:Print(L["The Rarity Options module has been disabled. Log out and enable it from your add-ons menu."])
 		end

Modules/Options/Options.lua

@@ -117,16 +117,6 @@ do
 		R.modulesEnabled.options = true
 
 		R:PrepareOptions()
-
-		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity", R.options)
-		R.optionsFrame = LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity", "Rarity")
-		R.profileOptions = LibStub("AceDBOptions-3.0"):GetOptionsTable(R.db)
-		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity-Profiles", R.profileOptions)
-		R.profileFrame = LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity-Profiles", "Profiles", "Rarity")
-
-		LibStub("AceConfig-3.0"):RegisterOptionsTable("Rarity-Advanced", R.advancedSettings)
-		R.advancedSettingsFrame =
-			LibStub("AceConfigDialog-3.0"):AddToBlizOptions("Rarity-Advanced", "Advanced", "Rarity")
 	end
 end