Just call UnitGUID("player") if saving the value in a static property.

diff --git a/OvaleDamageTaken.lua b/OvaleDamageTaken.lua
index 17e347d..1eb0a26 100644
--- a/OvaleDamageTaken.lua
+++ b/OvaleDamageTaken.lua
@@ -18,14 +18,14 @@ local OvalePool = Ovale.OvalePool
 local OvaleQueue = Ovale.OvaleQueue

 -- Forward declarations for module dependencies.
-local OvaleGUID = nil
 local OvaleLatency = nil

 local select = select
 local API_GetTime = GetTime
+local API_UnitGUID = UnitGUID

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")
 -- Damage event pool.
 local self_pool = OvalePool("OvaleDamageTaken_pool")
 -- Damage event queue: new events are inserted at the front of the queue.
@@ -50,12 +50,10 @@ end
 --<public-static-methods>
 function OvaleDamageTaken:OnInitialize()
 	-- Resolve module dependencies.
-	OvaleGUID = Ovale.OvaleGUID
 	OvaleLatency = Ovale.OvaleLatency
 end

 function OvaleDamageTaken:OnEnable()
-	self_guid = OvaleGUID:GetGUID("player")
 	self:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")
 	self:RegisterEvent("PLAYER_REGEN_ENABLED")
 end
diff --git a/OvaleEclipse.lua b/OvaleEclipse.lua
index 7c0edc0..651d778 100644
--- a/OvaleEclipse.lua
+++ b/OvaleEclipse.lua
@@ -18,18 +18,18 @@ Ovale.OvaleEclipse = OvaleEclipse
 --<private-static-properties>
 -- Forward declarations for module dependencies.
 local OvaleData = nil
-local OvaleGUID = nil
 local OvaleSpellBook = nil
 local OvaleState = nil

 local select = select
 local API_GetEclipseDirection = GetEclipseDirection
 local API_UnitClass = UnitClass
+local API_UnitGUID = UnitGUID
 local API_UnitPower = UnitPower
 local SPELL_POWER_ECLIPSE = SPELL_POWER_ECLIPSE

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")
 -- Player's class.
 local self_class = select(2, API_UnitClass("player"))

@@ -50,14 +50,12 @@ OvaleEclipse.eclipseDirection = 0
 function OvaleEclipse:OnInitialize()
 	-- Resolve module dependencies.
 	OvaleData = Ovale.OvaleData
-	OvaleGUID = Ovale.OvaleGUID
 	OvaleSpellBook = Ovale.OvaleSpellBook
 	OvaleState = Ovale.OvaleState
 end

 function OvaleEclipse:OnEnable()
 	if self_class == "DRUID" then
-		self_guid = OvaleGUID:GetGUID("player")
 		self:RegisterEvent("ECLIPSE_DIRECTION_CHANGE", "UpdateEclipseDirection")
 		self:RegisterEvent("UNIT_POWER")
 		self:RegisterEvent("UNIT_POWER_FREQUENT", "UNIT_POWER")
diff --git a/OvaleFuture.lua b/OvaleFuture.lua
index f2f7ac7..9466278 100644
--- a/OvaleFuture.lua
+++ b/OvaleFuture.lua
@@ -41,7 +41,7 @@ local API_UnitGUID = UnitGUID
 local API_UnitName = UnitName

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")

 -- The spells that the player is casting or has cast but are still in-flight toward their targets.
 local self_activeSpellcast = {}
@@ -109,10 +109,9 @@ local function GetDamageMultiplier(spellId)
 	if spellId then
 		local si = OvaleData.spellInfo[spellId]
 		if si and si.damageAura then
-			local playerGUID = OvaleGUID:GetGUID("player")
 			for filter, auraList in pairs(si.damageAura) do
 				for auraSpellId, multiplier in pairs(auraList) do
-					local aura = OvaleAura:GetAuraByGUID(playerGUID, auraSpellId, filter, nil, "player")
+					local aura = OvaleAura:GetAuraByGUID(self_guid, auraSpellId, filter, nil, "player")
 					if aura and aura.stacks > 0 then
 						local auraSpellInfo = OvaleData.spellInfo[auraSpellId]
 						if auraSpellInfo.stacking and auraSpellInfo.stacking > 0 then
@@ -271,7 +270,6 @@ function OvaleFuture:OnInitialize()
 end

 function OvaleFuture:OnEnable()
-	self_guid = OvaleGUID:GetGUID("player")
 	self:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")
 	self:RegisterEvent("PLAYER_ENTERING_WORLD")
 	self:RegisterEvent("UNIT_SPELLCAST_CHANNEL_START")
@@ -465,7 +463,7 @@ function OvaleFuture:COMBAT_LOG_EVENT_UNFILTERED(event, ...)
 	]]--

 	-- Called when a missile reaches or misses its target
-	if sourceGUID == OvaleGUID:GetGUID("player") then
+	if sourceGUID == self_guid then
 		if OVALE_CLEU_SPELLCAST_RESULTS[event] then
 			local spellId, spellName = select(12, ...)
 			TracePrintf(spellId, "%s: %s (%d)", event, spellName, spellId)
diff --git a/OvaleScore.lua b/OvaleScore.lua
index 2af313f..f92f372 100644
--- a/OvaleScore.lua
+++ b/OvaleScore.lua
@@ -34,15 +34,14 @@ Ovale.OvaleScore = OvaleScore

 --<private-static-properties>
 -- Forward declarations for module dependencies.
-local OvaleGUID = nil
-
 local pairs = pairs
 local strsplit = string.split
 local API_RegisterAddonMessagePrefix = RegisterAddonMessagePrefix
 local API_SendAddonMessage = SendAddonMessage
+local API_UnitGUID = UnitGUID

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")
 -- self_damageMeter[moduleName] = module
 local self_damageMeter = {}
 -- self_damageMeterMethod[moduleName] = methodName or function
@@ -59,13 +58,7 @@ local self_scoredSpell = {}
 --</public-static-properties>

 --<public-static-methods>
-function OvaleScore:OnInitialize()
-	-- Resolve module dependencies.
-	OvaleGUID = Ovale.OvaleGUID
-end
-
 function OvaleScore:OnEnable()
-	self_guid = OvaleGUID:GetGUID("player")
 	API_RegisterAddonMessagePrefix("Ovale")
 	self:RegisterEvent("CHAT_MSG_ADDON")
 	self:RegisterEvent("PLAYER_REGEN_ENABLED")
diff --git a/OvaleSpellDamage.lua b/OvaleSpellDamage.lua
index a486c47..05478f4 100644
--- a/OvaleSpellDamage.lua
+++ b/OvaleSpellDamage.lua
@@ -16,13 +16,12 @@ Ovale.OvaleSpellDamage = OvaleSpellDamage

 --<private-static-properties>
 -- Forward declarations for module dependencies.
-local OvaleGUID = nil
-
 local select = select
 local strfind = string.find
+local API_UnitGUID = UnitGUID

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")
 --</private-static-properties>

 --<public-static-properties>
@@ -30,12 +29,7 @@ OvaleSpellDamage.value = {}
 --</public-static-properties>

 --<public-static-methods>
-function OvaleSpellDamage:OnInitialize()
-	OvaleGUID = Ovale.OvaleGUID
-end
-
 function OvaleSpellDamage:OnEnable()
-	self_guid = OvaleGUID:GetGUID("player")
 	self:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")
 end

diff --git a/OvaleSwing.lua b/OvaleSwing.lua
index a125213..1551b5c 100644
--- a/OvaleSwing.lua
+++ b/OvaleSwing.lua
@@ -30,20 +30,18 @@ local OvaleSwing = Ovale:NewModule("OvaleSwing", "AceEvent-3.0")
 Ovale.OvaleSwing = OvaleSwing

 --<private-static-properties>
--- Forward declarations for module dependencies.
-local OvaleGUID = nil
-
 local math_abs = math.abs
 local unpack = unpack
 local API_GetSpellInfo = GetSpellInfo
 local API_GetTime = GetTime
 local API_IsDualWielding = IsDualWielding
 local API_UnitAttackSpeed = UnitAttackSpeed
+local API_UnitGUID = UnitGUID
 local API_UnitRangedDamage = UnitRangedDamage
 local BOOKTYPE_SPELL = BOOKTYPE_SPELL

 -- Player's GUID.
-local self_guid = nil
+local self_guid = API_UnitGUID("player")

 local OVALE_AUTOSHOT_NAME = API_GetSpellInfo(75)
 local OVALE_RESET_SPELLS = {}
@@ -66,14 +64,7 @@ OvaleSwing.swingmode = nil
 --</public-static-properties>

 --<public-static-methods>
-function OvaleSwing:OnInitialize()
-	-- Resolve module dependencies.
-	OvaleGUID = Ovale.OvaleGUID
-end
-
 function OvaleSwing:OnEnable()
-	self_guid = OvaleGUID:GetGUID("player")
-
 	self.ohNext = false
 	-- fired when autoattack is enabled/disabled.
 	self:RegisterEvent("PLAYER_ENTER_COMBAT")
@@ -116,7 +107,7 @@ function OvaleSwing:STOP_AUTOREPEAT_SPELL()
 end

 function OvaleSwing:COMBAT_LOG_EVENT_UNFILTERED(event, timestamp, eventName, srcGUID, srcName, srcFlags, dstName, dstGUID, dstFlags, ...)
-	if srcGUID == OvaleGUID:GetGUID("player") then
+	if srcGUID == self_guid then
 		if eventName == "SWING_DAMAGE" or eventName == "SWING_MISSED" then
 			local now = API_GetTime()
 			self:MeleeSwing(now)