[MIRROR] limb disabled refactor (#757)

* limb disabled refactor (#53374)

    Fixes #53219
    Nukes is_disabled()
    Turns several variable value changes into events.
    bodypart_disabled turned into a boolean value.
    BODYPART_DISABLED_WOUND turned into TRAIT_DISABLED_BY_WOUND. Not the cleanest thing out there, but it works.
    Cleans some code and reduces number of updates, as only the extremities have a disabled effect.

* limb disabled refactor

Co-authored-by: Rohesie <rohesie@gmail.com>

code/__DEFINES/mobs.dm

@@ -63,11 +63,6 @@
 #define BODYPART_ORGANIC   1
 #define BODYPART_ROBOTIC   2
 
-#define BODYPART_NOT_DISABLED 0
-#define BODYPART_DISABLED_DAMAGE 1
-#define BODYPART_DISABLED_PARALYSIS 2
-#define BODYPART_DISABLED_WOUND 3
-
 #define DEFAULT_BODYPART_ICON_ORGANIC 'icons/mob/human_parts_greyscale.dmi'
 #define DEFAULT_BODYPART_ICON_ROBOTIC 'icons/mob/augmentation/augments.dmi'
 

code/__DEFINES/traits.dm

@@ -203,7 +203,10 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 #define TRAIT_KNOW_ENGI_WIRES "know_engi_wires"
 
 //non-mob traits
-#define TRAIT_PARALYSIS				"paralysis" //Used for limb-based paralysis, where replacing the limb will fix it
+/// Used for limb-based paralysis, where replacing the limb will fix it.
+#define TRAIT_PARALYSIS				"paralysis"
+/// Used for limbs.
+#define TRAIT_DISABLED_BY_WOUND		"disabled-by-wound"
 
 ///Used for managing KEEP_TOGETHER in [appearance_flags]
 #define TRAIT_KEEP_TOGETHER 	"keep-together"

code/_onclick/other_mobs.dm

@@ -7,8 +7,8 @@
 /mob/living/carbon/human/UnarmedAttack(atom/A, proximity)
 	if(!has_active_hand()) //can't attack without a hand.
 		var/obj/item/bodypart/check_arm = get_active_hand()
-		if(check_arm && check_arm.is_disabled() == BODYPART_DISABLED_WOUND)
-			to_chat(src, "<span class='warning'>The damage in your [check_arm.name] is preventing you from using it! Get it fixed, or at least splinted!</span>")
+		if(check_arm?.bodypart_disabled)
+			to_chat(src, "<span class='warning'>Your [check_arm.name] is in no condition to be used.</span>")
 			return
 
 		to_chat(src, "<span class='notice'>You look at your arm and sigh.</span>")

code/datums/brain_damage/severe.dm

@@ -104,13 +104,13 @@
 	..()
 	for(var/X in paralysis_traits)
 		ADD_TRAIT(owner, X, "trauma_paralysis")
-	owner.update_disabled_bodyparts()
+
 
 /datum/brain_trauma/severe/paralysis/on_lose()
 	..()
 	for(var/X in paralysis_traits)
 		REMOVE_TRAIT(owner, X, "trauma_paralysis")
-	owner.update_disabled_bodyparts()
+
 
 /datum/brain_trauma/severe/paralysis/paraplegic
 	random_gain = FALSE

code/datums/wounds/_wounds.dm

@@ -95,7 +95,7 @@
 		QDEL_NULL(attached_surgery)
 	if(limb?.wounds && (src in limb.wounds)) // destroy can call remove_wound() and remove_wound() calls qdel, so we check to make sure there's anything to remove first
 		remove_wound()
-	limb = null
+	set_limb(null)
 	victim = null
 	return ..()
 
@@ -129,7 +129,7 @@
 			return
 
 	victim = L.owner
-	limb = L
+	set_limb(L)
 	LAZYADD(victim.all_wounds, src)
 	LAZYADD(limb.wounds, src)
 	limb.update_wounds()
@@ -192,13 +192,45 @@
 	already_scarred = TRUE
 	remove_wound(replaced=TRUE)
 	new_wound.apply_wound(limb, old_wound = src, smited = smited)
+	. = new_wound
 	qdel(src)
-	return new_wound
 
 /// The immediate negative effects faced as a result of the wound
 /datum/wound/proc/wound_injury(datum/wound/old_wound = null)
 	return
 
+
+/// Proc called to change the variable `limb` and react to the event.
+/datum/wound/proc/set_limb(new_value)
+	if(limb == new_value)
+		return FALSE //Limb can either be a reference to something or `null`. Returning the number variable makes it clear no change was made.
+	. = limb
+	limb = new_value
+	if(. && disabling)
+		var/obj/item/bodypart/old_limb = .
+		REMOVE_TRAIT(old_limb, TRAIT_PARALYSIS, src)
+		REMOVE_TRAIT(old_limb, TRAIT_DISABLED_BY_WOUND, src)
+	if(limb)
+		if(disabling)
+			ADD_TRAIT(limb, TRAIT_PARALYSIS, src)
+			ADD_TRAIT(limb, TRAIT_DISABLED_BY_WOUND, src)
+
+
+/// Proc called to change the variable `disabling` and react to the event.
+/datum/wound/proc/set_disabling(new_value)
+	if(disabling == new_value)
+		return
+	. = disabling
+	disabling = new_value
+	if(disabling)
+		if(!. && limb) //Gained disabling.
+			ADD_TRAIT(limb, TRAIT_PARALYSIS, src)
+			ADD_TRAIT(limb, TRAIT_DISABLED_BY_WOUND, src)
+	else if(. && limb) //Lost disabling.
+		REMOVE_TRAIT(limb, TRAIT_PARALYSIS, src)
+		REMOVE_TRAIT(limb, TRAIT_DISABLED_BY_WOUND, src)
+
+
 /// Additional beneficial effects when the wound is gained, in case you want to give a temporary boost to allow the victim to try an escape or last stand
 /datum/wound/proc/second_wind()
 	switch(severity)

code/datums/wounds/bones.dm

@@ -177,7 +177,7 @@
 			interaction_efficiency_penalty = interaction_efficiency_penalty
 
 	if(initial(disabling))
-		disabling = !limb.current_gauze
+		set_disabling(!limb.current_gauze)
 
 	limb.update_wounds()
 

code/datums/wounds/burns.dm

@@ -82,19 +82,19 @@
 		if(WOUND_INFECTION_SEVERE to WOUND_INFECTION_CRITICAL)
 			if(!disabling && prob(2))
 				to_chat(victim, "<span class='warning'><b>Your [limb.name] completely locks up, as you struggle for control against the infection!</b></span>")
-				disabling = TRUE
+				set_disabling(TRUE)
 			else if(disabling && prob(8))
 				to_chat(victim, "<span class='notice'>You regain sensation in your [limb.name], but it's still in terrible shape!</span>")
-				disabling = FALSE
+				set_disabling(FALSE)
 			else if(prob(20))
 				victim.adjustToxLoss(0.5)
 		if(WOUND_INFECTION_CRITICAL to WOUND_INFECTION_SEPTIC)
 			if(!disabling && prob(3))
 				to_chat(victim, "<span class='warning'><b>You suddenly lose all sensation of the festering infection in your [limb.name]!</b></span>")
-				disabling = TRUE
+				set_disabling(TRUE)
 			else if(disabling && prob(3))
 				to_chat(victim, "<span class='notice'>You can barely feel your [limb.name] again, and you have to strain to retain motor control!</span>")
-				disabling = FALSE
+				set_disabling(FALSE)
 			else if(prob(1))
 				to_chat(victim, "<span class='warning'>You contemplate life without your [limb.name]...</span>")
 				victim.adjustToxLoss(0.75)

code/datums/wounds/loss.dm

@@ -46,7 +46,7 @@
 
 	victim.visible_message(msg, "<span class='userdanger'>Your [dismembered_part.name] [occur_text]!</span>")
 
-	limb = dismembered_part
+	set_limb(dismembered_part)
 	severity = WOUND_SEVERITY_LOSS
 	second_wind()
 	log_wound(victim, src)

code/modules/mob/living/carbon/carbon.dm

@@ -967,7 +967,7 @@
 	var/r_arm_index_next = 0
 	for(var/bodypart_path in bodyparts)
 		var/obj/item/bodypart/bodypart_instance = new bodypart_path()
-		bodypart_instance.owner = src
+		bodypart_instance.set_owner(src)
 		bodyparts.Remove(bodypart_path)
 		add_bodypart(bodypart_instance)
 		switch(bodypart_instance.body_part)
@@ -1016,10 +1016,6 @@
 		var/obj/item/organ/I = X
 		I.Insert(src)
 
-/mob/living/carbon/proc/update_disabled_bodyparts()
-	for(var/B in bodyparts)
-		var/obj/item/bodypart/BP = B
-		BP.update_disabled()
 
 /mob/living/carbon/vv_get_dropdown()
 	. = ..()

code/modules/mob/living/carbon/human/examine.dm

@@ -157,12 +157,13 @@
 	for(var/X in disabled)
 		var/obj/item/bodypart/body_part = X
 		var/damage_text
-		if(body_part.is_disabled() != BODYPART_DISABLED_WOUND) // skip if it's disabled by a wound (cuz we'll be able to see the bone sticking out!)
-			if(!(body_part.get_damage(include_stamina = FALSE) >= body_part.max_damage)) //we don't care if it's stamcritted
-				damage_text = "limp and lifeless"
-			else
-				damage_text = (body_part.brute_dam >= body_part.burn_dam) ? body_part.heavy_brute_msg : body_part.heavy_burn_msg
-			msg += "<B>[capitalize(t_his)] [body_part.name] is [damage_text]!</B>\n"
+		if(HAS_TRAIT(body_part, TRAIT_DISABLED_BY_WOUND))
+			continue // skip if it's disabled by a wound (cuz we'll be able to see the bone sticking out!)
+		if(!(body_part.get_damage(include_stamina = FALSE) >= body_part.max_damage)) //we don't care if it's stamcritted
+			damage_text = "limp and lifeless"
+		else
+			damage_text = (body_part.brute_dam >= body_part.burn_dam) ? body_part.heavy_brute_msg : body_part.heavy_burn_msg
+		msg += "<B>[capitalize(t_his)] [body_part.name] is [damage_text]!</B>\n"
 
 	//stores missing limbs
 	var/l_limbs_missing = 0

code/modules/mob/living/carbon/human/human_defense.dm

@@ -717,7 +717,7 @@
 		if(status == "OK" || status == "no damage")
 			no_damage = TRUE
 		var/isdisabled = ""
-		if(LB.is_disabled())
+		if(LB.bodypart_disabled)
 			isdisabled = " is disabled"
 			if(no_damage)
 				isdisabled += " but otherwise"

code/modules/surgery/bodyparts/_bodyparts.dm

@@ -22,7 +22,12 @@
 	var/held_index = 0 //are we a hand? if so, which one!
 	var/is_pseudopart = FALSE //For limbs that don't really exist, eg chainsaws
 
-	var/bodypart_disabled = BODYPART_NOT_DISABLED //If disabled, limb is as good as missing
+	///If disabled, limb is as good as missing.
+	var/bodypart_disabled = FALSE
+	///Multiplied by max_damage it returns the threshold which defines a limb being disabled or not. From 0 to 1.
+	var/disable_threshold = 1
+	///Controls whether bodypart_disabled makes sense or not for this limb.
+	var/can_be_disabled = FALSE
 	var/body_damage_coeff = 1 //Multiplier of the limb's damage that gets applied to the mob
 	var/stam_damage_coeff = 0.75
 	var/brutestate = 0
@@ -91,6 +96,25 @@
 	var/obj/item/self_grasp/grasped_by
 
 
+/obj/item/bodypart/Initialize(mapload)
+	. = ..()
+	if(can_be_disabled)
+		RegisterSignal(src, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS), .proc/on_paralysis_trait_gain)
+		RegisterSignal(src, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS), .proc/on_paralysis_trait_loss)
+
+
+/obj/item/bodypart/Destroy()
+	if(owner)
+		owner.remove_bodypart(src)
+		set_owner(null)
+	for(var/wound in wounds)
+		qdel(wound) // wounds is a lazylist, and each wound removes itself from it on deletion.
+	if(length(wounds))
+		stack_trace("[type] qdeleted with [length(wounds)] uncleared wounds")
+		wounds.Cut()
+	return ..()
+
+
 /obj/item/bodypart/examine(mob/user)
 	. = ..()
 	if(brute_dam > DAMAGE_PRECISION)
@@ -98,14 +122,10 @@
 	if(burn_dam > DAMAGE_PRECISION)
 		. += "<span class='warning'>This limb has [burn_dam > 30 ? "severe" : "minor"] burns.</span>"
 
+
 /obj/item/bodypart/blob_act()
 	take_damage(max_damage)
 
-/obj/item/bodypart/Destroy()
-	if(owner)
-		owner.remove_bodypart(src)
-		owner = null
-	return ..()
 
 /obj/item/bodypart/attack(mob/living/carbon/C, mob/user)
 	if(ishuman(C))
@@ -171,13 +191,6 @@
 
 	return bodypart_organs
 
-/obj/item/bodypart/proc/consider_processing()
-	if(stamina_dam > DAMAGE_PRECISION)
-		. = TRUE
-	//else if.. else if.. so on.
-	else
-		. = FALSE
-	needs_processing = .
 
 //Return TRUE to get whatever mob this is in to update health.
 /obj/item/bodypart/proc/on_life(stam_regen)
@@ -279,21 +292,24 @@
 
 	if(can_inflict <= 0)
 		return FALSE
-
-	brute_dam += brute
-	burn_dam += burn
+	if(brute)
+		set_brute_dam(brute_dam + brute)
+	if(burn)
+		set_burn_dam(burn_dam + burn)
 
 	//We've dealt the physical damages, if there's room lets apply the stamina damage.
-	stamina_dam += round(clamp(stamina, 0, max_stamina_damage - stamina_dam), DAMAGE_PRECISION)
+	if(stamina)
+		set_stamina_dam(stamina_dam + round(clamp(stamina, 0, max_stamina_damage - stamina_dam), DAMAGE_PRECISION))
 
-	if(owner && updating_health)
-		owner.updatehealth()
-		if(stamina > DAMAGE_PRECISION)
-			owner.update_stamina()
-			owner.stam_regen_start_time = world.time + STAMINA_REGEN_BLOCK_TIME
-			. = TRUE
-	consider_processing()
-	update_disabled()
+	if(owner)
+		if(can_be_disabled)
+			update_disabled()
+		if(updating_health)
+			owner.updatehealth()
+			if(stamina > DAMAGE_PRECISION)
+				owner.update_stamina()
+				owner.stam_regen_start_time = world.time + STAMINA_REGEN_BLOCK_TIME
+				. = TRUE
 	return update_bodypart_damage_state() || .
 
 /// Allows us to roll for and apply a wound without actually dealing damage. Used for aggregate wounding power with pellet clouds
@@ -468,19 +484,53 @@
 //Cannot remove negative damage (i.e. apply damage)
 /obj/item/bodypart/proc/heal_damage(brute, burn, stamina, required_status, updating_health = TRUE)
 
-	if(required_status && (status != required_status)) //So we can only heal certain kinds of limbs, ie robotic vs organic.
+	if(required_status && status != required_status) //So we can only heal certain kinds of limbs, ie robotic vs organic.
 		return
 
-	brute_dam	= round(max(brute_dam - brute, 0), DAMAGE_PRECISION)
-	burn_dam	= round(max(burn_dam - burn, 0), DAMAGE_PRECISION)
-	stamina_dam = round(max(stamina_dam - stamina, 0), DAMAGE_PRECISION)
-	if(owner && updating_health)
-		owner.updatehealth()
-	consider_processing()
-	update_disabled()
+	if(brute)
+		set_brute_dam(round(max(brute_dam - brute, 0), DAMAGE_PRECISION))
+	if(burn)
+		set_burn_dam(round(max(burn_dam - burn, 0), DAMAGE_PRECISION))
+	if(stamina)
+		set_stamina_dam(round(max(stamina_dam - stamina, 0), DAMAGE_PRECISION))
+
+	if(owner)
+		if(can_be_disabled)
+			update_disabled()
+		if(updating_health)
+			owner.updatehealth()
 	cremation_progress = min(0, cremation_progress - ((brute_dam + burn_dam)*(100/max_damage)))
 	return update_bodypart_damage_state()
 
+
+///Proc to hook behavior associated to the change of the brute_dam variable's value.
+/obj/item/bodypart/proc/set_brute_dam(new_value)
+	if(brute_dam == new_value)
+		return
+	. = brute_dam
+	brute_dam = new_value
+
+
+///Proc to hook behavior associated to the change of the burn_dam variable's value.
+/obj/item/bodypart/proc/set_burn_dam(new_value)
+	if(burn_dam == new_value)
+		return
+	. = burn_dam
+	burn_dam = new_value
+
+
+///Proc to hook behavior associated to the change of the stamina_dam variable's value.
+/obj/item/bodypart/proc/set_stamina_dam(new_value)
+	if(stamina_dam == new_value)
+		return
+	. = stamina_dam
+	stamina_dam = new_value
+	if(stamina_dam > DAMAGE_PRECISION)
+		needs_processing = TRUE
+	else
+		needs_processing = FALSE
+
+
 //Returns total damage.
 /obj/item/bodypart/proc/get_damage(include_stamina = FALSE)
 	var/total = brute_dam + burn_dam
@@ -488,51 +538,166 @@
 		total = max(total, stamina_dam)
 	return total
 
+
 //Checks disabled status thresholds
 /obj/item/bodypart/proc/update_disabled()
 	if(!owner)
 		return
-	if(!isnull(set_disabled(is_disabled()))) //set_disabled will return null when there's no change
-		owner.update_mobility()
 
+	if(!can_be_disabled)
+		set_disabled(FALSE)
+		CRASH("update_disabled called with can_be_disabled false")
 
-/obj/item/bodypart/proc/is_disabled()
-	if(!owner)
-		return
 	if(HAS_TRAIT(src, TRAIT_PARALYSIS))
-		return BODYPART_DISABLED_PARALYSIS
-	for(var/i in wounds)
-		var/datum/wound/W = i
-		if(W.disabling)
-			return BODYPART_DISABLED_WOUND
-	if(can_dismember() && !HAS_TRAIT(owner, TRAIT_NOLIMBDISABLE))
-		. = bodypart_disabled //inertia, to avoid limbs healing 0.1 damage and being re-enabled
+		set_disabled(TRUE)
+		return
 
-		if(get_damage(TRUE) >= max_damage * (HAS_TRAIT(owner, TRAIT_EASYLIMBWOUND) ? 0.6 : 1)) //Easy limb disable disables the limb at 40% health instead of 0%
-			if(!last_maxed)
+	var/total_damage = max(brute_dam + burn_dam, stamina_dam)
+
+	if(total_damage >= max_damage * disable_threshold) //Easy limb disable disables the limb at 40% health instead of 0%
+		if(!last_maxed)
+			if(owner.stat < UNCONSCIOUS)
 				owner.emote("scream")
-				last_maxed = TRUE
-			if(!is_organic_limb() || stamina_dam >= max_damage)
-				return BODYPART_DISABLED_DAMAGE
-		else if(bodypart_disabled && (get_damage(TRUE) <= (max_damage * 0.8))) // reenabled at 80% now instead of 50% as of wounds update
-			last_maxed = FALSE
-			return BODYPART_NOT_DISABLED
-	else
-		return BODYPART_NOT_DISABLED
-	return BODYPART_NOT_DISABLED
+			last_maxed = TRUE
+		set_disabled(TRUE)
+		return
+
+	if(bodypart_disabled && total_damage <= max_damage * 0.8) // reenabled at 80% now instead of 50% as of wounds update
+		last_maxed = FALSE
+		set_disabled(FALSE)
 
 
+///Proc to change the value of the `disabled` variable and react to the event of its change.
 /obj/item/bodypart/proc/set_disabled(new_disabled)
-	if(isnull(new_disabled) || bodypart_disabled == new_disabled || !owner)
+	if(bodypart_disabled == new_disabled)
 		return
 	. = bodypart_disabled
 	bodypart_disabled = new_disabled
-	if(bodypart_disabled && owner.get_item_for_held_index(held_index))
-		owner.dropItemToGround(owner.get_item_for_held_index(held_index))
+
+	if(!owner)
+		return
+	if(bodypart_disabled)
+		if(!.)
+			owner.update_mobility()
+	else if (.)
+		owner.update_mobility()
 	owner.update_health_hud() //update the healthdoll
 	owner.update_body()
 
 
+///Proc to change the value of the `owner` variable and react to the event of its change.
+/obj/item/bodypart/proc/set_owner(new_owner)
+	if(owner == new_owner)
+		return FALSE //`null` is a valid option, so we need to use a num var to make it clear no change was made.
+	. = owner
+	owner = new_owner
+	var/needs_update_disabled = FALSE //Only really relevant if there's an owner
+	if(.)
+		var/mob/living/carbon/old_owner = .
+		if(can_be_disabled)
+			if(HAS_TRAIT(old_owner, TRAIT_EASYLIMBWOUND))
+				disable_threshold = initial(disable_threshold)
+				needs_update_disabled = TRUE
+			UnregisterSignal(old_owner, list(
+				SIGNAL_REMOVETRAIT(TRAIT_EASYLIMBWOUND),
+				SIGNAL_ADDTRAIT(TRAIT_EASYLIMBWOUND),
+				))
+		if(initial(can_be_disabled))
+			if(HAS_TRAIT(old_owner, TRAIT_NOLIMBDISABLE))
+				if(!owner || !HAS_TRAIT(owner, TRAIT_NOLIMBDISABLE))
+					set_can_be_disabled(initial(can_be_disabled))
+					needs_update_disabled = TRUE
+			UnregisterSignal(old_owner, list(
+				SIGNAL_REMOVETRAIT(TRAIT_NOLIMBDISABLE),
+				SIGNAL_ADDTRAIT(TRAIT_NOLIMBDISABLE),
+				))
+	if(owner)
+		if(can_be_disabled)
+			if(HAS_TRAIT(owner, TRAIT_EASYLIMBWOUND))
+				disable_threshold = 0.6
+				needs_update_disabled = TRUE
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_EASYLIMBWOUND), .proc/on_owner_easylimbwound_trait_loss)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_EASYLIMBWOUND), .proc/on_owner_easylimbwound_trait_gain)
+		if(initial(can_be_disabled))
+			if(HAS_TRAIT(owner, TRAIT_NOLIMBDISABLE))
+				set_can_be_disabled(FALSE)
+				needs_update_disabled = FALSE
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_NOLIMBDISABLE), .proc/on_owner_nolimbdisable_trait_loss)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_NOLIMBDISABLE), .proc/on_owner_nolimbdisable_trait_gain)
+		if(needs_update_disabled)
+			update_disabled()
+
+
+///Proc to change the value of the `can_be_disabled` variable and react to the event of its change.
+/obj/item/bodypart/proc/set_can_be_disabled(new_can_be_disabled)
+	if(can_be_disabled == new_can_be_disabled)
+		return
+	. = can_be_disabled
+	can_be_disabled = new_can_be_disabled
+	if(can_be_disabled)
+		if(owner)
+			if(HAS_TRAIT(owner, TRAIT_NOLIMBDISABLE))
+				CRASH("set_can_be_disabled to TRUE with for limb whose owner has TRAIT_NOLIMBDISABLE")
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS), .proc/on_paralysis_trait_gain)
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS), .proc/on_paralysis_trait_loss)
+			if(HAS_TRAIT(owner, TRAIT_EASYLIMBWOUND))
+				disable_threshold = 0.6
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_EASYLIMBWOUND), .proc/on_owner_easylimbwound_trait_loss)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_EASYLIMBWOUND), .proc/on_owner_easylimbwound_trait_gain)
+		update_disabled()
+	else if(.)
+		if(owner)
+			UnregisterSignal(owner, list(
+				SIGNAL_ADDTRAIT(TRAIT_PARALYSIS),
+				SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS),
+				SIGNAL_REMOVETRAIT(TRAIT_EASYLIMBWOUND),
+				SIGNAL_ADDTRAIT(TRAIT_EASYLIMBWOUND),
+				))
+		set_disabled(FALSE)
+
+
+///Called when TRAIT_PARALYSIS is added to the limb.
+/obj/item/bodypart/proc/on_paralysis_trait_gain(obj/item/bodypart/source)
+	SIGNAL_HANDLER
+	if(can_be_disabled)
+		set_disabled(TRUE)
+
+
+///Called when TRAIT_PARALYSIS is removed from the limb.
+/obj/item/bodypart/proc/on_paralysis_trait_loss(obj/item/bodypart/source)
+	SIGNAL_HANDLER
+	if(can_be_disabled)
+		update_disabled()
+
+
+///Called when TRAIT_NOLIMBDISABLE is added to the owner.
+/obj/item/bodypart/proc/on_owner_nolimbdisable_trait_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	set_can_be_disabled(FALSE)
+
+
+///Called when TRAIT_NOLIMBDISABLE is removed from the owner.
+/obj/item/bodypart/proc/on_owner_nolimbdisable_trait_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	set_can_be_disabled(initial(can_be_disabled))
+
+
+///Called when TRAIT_EASYLIMBWOUND is added to the owner.
+/obj/item/bodypart/proc/on_owner_easylimbwound_trait_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	disable_threshold = 0.6
+	if(can_be_disabled)
+		update_disabled()
+
+
+///Called when TRAIT_EASYLIMBWOUND is removed from the owner.
+/obj/item/bodypart/proc/on_owner_easylimbwound_trait_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	disable_threshold = initial(disable_threshold)
+	if(can_be_disabled)
+		update_disabled()
+
+
 //Updates an organ's brute/burn states for use by update_damage_overlays()
 //Returns 1 if we need to update overlays. 0 otherwise.
 /obj/item/bodypart/proc/update_bodypart_damage_state()
@@ -754,7 +919,7 @@
 		QDEL_NULL(current_gauze)
 
 	wound_damage_multiplier = dam_mul
-	update_disabled()
+
 
 /obj/item/bodypart/proc/get_bleed_rate()
 	if(status != BODYPART_ORGANIC) // maybe in the future we can bleed oil from aug parts, but not now

code/modules/surgery/bodyparts/dismemberment.dm

@@ -455,8 +455,8 @@
 	L = newBodyPart(limb_zone, 0, 0)
 	if(L)
 		if(!noheal)
-			L.brute_dam = 0
-			L.burn_dam = 0
+			L.set_brute_dam(0)
+			L.set_burn_dam(0)
 			L.brutestate = 0
 			L.burnstate = 0
 

code/modules/surgery/bodyparts/parts.dm

@@ -72,35 +72,62 @@
 	held_index = 1
 	px_x = -6
 	px_y = 0
+	can_be_disabled = TRUE
 
-/obj/item/bodypart/l_arm/is_disabled()
-	if(HAS_TRAIT(owner, TRAIT_PARALYSIS_L_ARM))
-		return BODYPART_DISABLED_PARALYSIS
-	return ..()
+
+/obj/item/bodypart/l_arm/set_owner(new_owner)
+	. = ..()
+	if(. == FALSE)
+		return
+	var/mob/living/carbon/owner = null
+	if(owner)
+		if(HAS_TRAIT(owner, TRAIT_PARALYSIS_L_ARM))
+			ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_ARM)
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_ARM), .proc/on_owner_paralysis_loss)
+		else
+			REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_ARM)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_ARM), .proc/on_owner_paralysis_gain)
+	if(.)
+		var/mob/living/carbon/old_owner = .
+		if(HAS_TRAIT(old_owner, TRAIT_PARALYSIS_L_ARM))
+			UnregisterSignal(old_owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_ARM))
+			if(!owner || !HAS_TRAIT(owner, TRAIT_PARALYSIS_L_ARM))
+				REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_ARM)
+		else
+			UnregisterSignal(old_owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_ARM))
+
+
+///Proc to react to the owner gaining the TRAIT_PARALYSIS_L_ARM trait.
+/obj/item/bodypart/l_arm/proc/on_owner_paralysis_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_ARM)
+	UnregisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_ARM))
+	RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_ARM), .proc/on_owner_paralysis_loss)
+
+
+///Proc to react to the owner losing the TRAIT_PARALYSIS_L_ARM trait.
+/obj/item/bodypart/l_arm/proc/on_owner_paralysis_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_ARM)
+	UnregisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_ARM))
+	RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_ARM), .proc/on_owner_paralysis_gain)
 
 
 /obj/item/bodypart/l_arm/set_disabled(new_disabled)
 	. = ..()
-	if(isnull(.))
+	if(isnull(.) || !owner)
 		return
-	if(. == BODYPART_NOT_DISABLED)
-		if(bodypart_disabled != BODYPART_NOT_DISABLED)
-			owner.set_usable_hands(owner.usable_hands + 1)
-	else if(bodypart_disabled == BODYPART_NOT_DISABLED)
-		owner.set_usable_hands(owner.usable_hands - 1)
-	switch(bodypart_disabled)
-		if(BODYPART_DISABLED_DAMAGE)
+
+	if(!.)
+		if(bodypart_disabled)
+			owner.set_usable_hands(owner.usable_hands - 1)
 			if(owner.stat < UNCONSCIOUS)
-				owner.emote("scream")
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>Your [name] is too damaged to function!</span>")
+				to_chat(owner, "<span class='userdanger'>Your lose control of your [name]!</span>")
 			if(held_index)
 				owner.dropItemToGround(owner.get_item_for_held_index(held_index))
-		if(BODYPART_DISABLED_PARALYSIS)
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>You can't feel your [name]!</span>")
-				if(held_index)
-					owner.dropItemToGround(owner.get_item_for_held_index(held_index))
+	else if(!bodypart_disabled)
+		owner.set_usable_hands(owner.usable_hands + 1)
+
 	if(owner.hud_used)
 		var/obj/screen/inventory/hand/hand_screen_object = owner.hud_used.hand_slots["[held_index]"]
 		hand_screen_object?.update_icon()
@@ -119,12 +146,14 @@
 	icon_state = "alien_l_arm"
 	px_x = 0
 	px_y = 0
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 100
 	animal_origin = ALIEN_BODYPART
 
 /obj/item/bodypart/l_arm/devil
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 5000
 	animal_origin = DEVIL_BODYPART
 
@@ -145,35 +174,62 @@
 	px_x = 6
 	px_y = 0
 	max_stamina_damage = 50
+	can_be_disabled = TRUE
 
-/obj/item/bodypart/r_arm/is_disabled()
-	if(HAS_TRAIT(owner, TRAIT_PARALYSIS_R_ARM))
-		return BODYPART_DISABLED_PARALYSIS
-	return ..()
+
+/obj/item/bodypart/r_arm/set_owner(new_owner)
+	. = ..()
+	if(. == FALSE)
+		return
+	var/mob/living/carbon/owner = null
+	if(owner)
+		if(HAS_TRAIT(owner, TRAIT_PARALYSIS_R_ARM))
+			ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_ARM)
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_ARM), .proc/on_owner_paralysis_loss)
+		else
+			REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_ARM)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_ARM), .proc/on_owner_paralysis_gain)
+	if(.)
+		var/mob/living/carbon/old_owner = .
+		if(HAS_TRAIT(old_owner, TRAIT_PARALYSIS_R_ARM))
+			UnregisterSignal(old_owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_ARM))
+			if(!owner || !HAS_TRAIT(owner, TRAIT_PARALYSIS_R_ARM))
+				REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_ARM)
+		else
+			UnregisterSignal(old_owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_ARM))
+
+
+///Proc to react to the owner gaining the TRAIT_PARALYSIS_R_ARM trait.
+/obj/item/bodypart/r_arm/proc/on_owner_paralysis_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_ARM)
+	UnregisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_ARM))
+	RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_ARM), .proc/on_owner_paralysis_loss)
+
+
+///Proc to react to the owner losing the TRAIT_PARALYSIS_R_ARM trait.
+/obj/item/bodypart/r_arm/proc/on_owner_paralysis_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_ARM)
+	UnregisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_ARM))
+	RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_ARM), .proc/on_owner_paralysis_gain)
 
 
 /obj/item/bodypart/r_arm/set_disabled(new_disabled)
 	. = ..()
-	if(isnull(.))
+	if(isnull(.) || !owner)
 		return
-	if(. == BODYPART_NOT_DISABLED)
-		if(bodypart_disabled != BODYPART_NOT_DISABLED)
-			owner.set_usable_hands(owner.usable_hands + 1)
-	else if(bodypart_disabled == BODYPART_NOT_DISABLED)
-		owner.set_usable_hands(owner.usable_hands - 1)
-	switch(bodypart_disabled)
-		if(BODYPART_DISABLED_DAMAGE)
+
+	if(!.)
+		if(bodypart_disabled)
+			owner.set_usable_hands(owner.usable_hands - 1)
 			if(owner.stat < UNCONSCIOUS)
-				owner.emote("scream")
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>Your [name] is too damaged to function!</span>")
+				to_chat(owner, "<span class='userdanger'>Your lose control of your [name]!</span>")
 			if(held_index)
 				owner.dropItemToGround(owner.get_item_for_held_index(held_index))
-		if(BODYPART_DISABLED_PARALYSIS)
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>You can't feel your [name]!</span>")
-				if(held_index)
-					owner.dropItemToGround(owner.get_item_for_held_index(held_index))
+	else if(!bodypart_disabled)
+		owner.set_usable_hands(owner.usable_hands + 1)
+
 	if(owner.hud_used)
 		var/obj/screen/inventory/hand/hand_screen_object = owner.hud_used.hand_slots["[held_index]"]
 		hand_screen_object?.update_icon()
@@ -192,12 +248,14 @@
 	icon_state = "alien_r_arm"
 	px_x = 0
 	px_y = 0
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 100
 	animal_origin = ALIEN_BODYPART
 
 /obj/item/bodypart/r_arm/devil
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 5000
 	animal_origin = DEVIL_BODYPART
 
@@ -215,31 +273,58 @@
 	px_x = -2
 	px_y = 12
 	max_stamina_damage = 50
+	can_be_disabled = TRUE
 
-/obj/item/bodypart/l_leg/is_disabled()
-	if(HAS_TRAIT(owner, TRAIT_PARALYSIS_L_LEG))
-		return BODYPART_DISABLED_PARALYSIS
-	return ..()
+
+/obj/item/bodypart/l_leg/set_owner(new_owner)
+	. = ..()
+	if(. == FALSE)
+		return
+	if(owner)
+		if(HAS_TRAIT(owner, TRAIT_PARALYSIS_L_LEG))
+			ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_LEG)
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_LEG), .proc/on_owner_paralysis_loss)
+		else
+			REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_LEG)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_LEG), .proc/on_owner_paralysis_gain)
+	if(.)
+		var/mob/living/carbon/old_owner = .
+		if(HAS_TRAIT(old_owner, TRAIT_PARALYSIS_L_LEG))
+			UnregisterSignal(old_owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_LEG))
+			if(!owner || !HAS_TRAIT(owner, TRAIT_PARALYSIS_L_LEG))
+				REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_LEG)
+		else
+			UnregisterSignal(old_owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_LEG))
+
+
+///Proc to react to the owner gaining the TRAIT_PARALYSIS_L_LEG trait.
+/obj/item/bodypart/l_leg/proc/on_owner_paralysis_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_LEG)
+	UnregisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_LEG))
+	RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_LEG), .proc/on_owner_paralysis_loss)
+
+
+///Proc to react to the owner losing the TRAIT_PARALYSIS_L_LEG trait.
+/obj/item/bodypart/l_leg/proc/on_owner_paralysis_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_L_LEG)
+	UnregisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_L_LEG))
+	RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_L_LEG), .proc/on_owner_paralysis_gain)
 
 
 /obj/item/bodypart/l_leg/set_disabled(new_disabled)
 	. = ..()
-	if(isnull(.))
+	if(isnull(.) || !owner)
 		return
-	if(. == BODYPART_NOT_DISABLED)
-		if(bodypart_disabled != BODYPART_NOT_DISABLED)
-			owner.set_usable_legs(owner.usable_legs + 1)
-	else if(bodypart_disabled == BODYPART_NOT_DISABLED)
-		owner.set_usable_legs(owner.usable_legs - 1)
-	switch(bodypart_disabled)
-		if(BODYPART_DISABLED_DAMAGE)
+
+	if(!.)
+		if(bodypart_disabled)
+			owner.set_usable_legs(owner.usable_legs - 1)
 			if(owner.stat < UNCONSCIOUS)
-				owner.emote("scream")
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>Your [name] is too damaged to function!</span>")
-		if(BODYPART_DISABLED_PARALYSIS)
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>You can't feel your [name]!</span>")
+				to_chat(owner, "<span class='userdanger'>Your lose control of your [name]!</span>")
+	else if(!bodypart_disabled)
+		owner.set_usable_legs(owner.usable_legs + 1)
 
 
 /obj/item/bodypart/l_leg/digitigrade
@@ -258,12 +343,14 @@
 	icon_state = "alien_l_leg"
 	px_x = 0
 	px_y = 0
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 100
 	animal_origin = ALIEN_BODYPART
 
 /obj/item/bodypart/l_leg/devil
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 5000
 	animal_origin = DEVIL_BODYPART
 
@@ -283,31 +370,58 @@
 	px_x = 2
 	px_y = 12
 	max_stamina_damage = 50
+	can_be_disabled = TRUE
 
-/obj/item/bodypart/r_leg/is_disabled()
-	if(HAS_TRAIT(owner, TRAIT_PARALYSIS_R_LEG))
-		return BODYPART_DISABLED_PARALYSIS
-	return ..()
+
+/obj/item/bodypart/r_leg/set_owner(new_owner)
+	. = ..()
+	if(. == FALSE)
+		return
+	if(owner)
+		if(HAS_TRAIT(owner, TRAIT_PARALYSIS_R_LEG))
+			ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_LEG)
+			RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_LEG), .proc/on_owner_paralysis_loss)
+		else
+			REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_LEG)
+			RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_LEG), .proc/on_owner_paralysis_gain)
+	if(.)
+		var/mob/living/carbon/old_owner = .
+		if(HAS_TRAIT(old_owner, TRAIT_PARALYSIS_R_LEG))
+			UnregisterSignal(old_owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_LEG))
+			if(!owner || !HAS_TRAIT(owner, TRAIT_PARALYSIS_R_LEG))
+				REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_LEG)
+		else
+			UnregisterSignal(old_owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_LEG))
+
+
+///Proc to react to the owner gaining the TRAIT_PARALYSIS_R_LEG trait.
+/obj/item/bodypart/r_leg/proc/on_owner_paralysis_gain(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	ADD_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_LEG)
+	UnregisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_LEG))
+	RegisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_LEG), .proc/on_owner_paralysis_loss)
+
+
+///Proc to react to the owner losing the TRAIT_PARALYSIS_R_LEG trait.
+/obj/item/bodypart/r_leg/proc/on_owner_paralysis_loss(mob/living/carbon/source)
+	SIGNAL_HANDLER
+	REMOVE_TRAIT(src, TRAIT_PARALYSIS, TRAIT_PARALYSIS_R_LEG)
+	UnregisterSignal(owner, SIGNAL_REMOVETRAIT(TRAIT_PARALYSIS_R_LEG))
+	RegisterSignal(owner, SIGNAL_ADDTRAIT(TRAIT_PARALYSIS_R_LEG), .proc/on_owner_paralysis_gain)
 
 
 /obj/item/bodypart/r_leg/set_disabled(new_disabled)
 	. = ..()
-	if(isnull(.))
+	if(isnull(.) || !owner)
 		return
-	if(. == BODYPART_NOT_DISABLED)
-		if(bodypart_disabled != BODYPART_NOT_DISABLED)
-			owner.set_usable_legs(owner.usable_legs + 1)
-	else if(bodypart_disabled == BODYPART_NOT_DISABLED)
-		owner.set_usable_legs(owner.usable_legs - 1)
-	switch(bodypart_disabled)
-		if(BODYPART_DISABLED_DAMAGE)
+
+	if(!.)
+		if(bodypart_disabled)
+			owner.set_usable_legs(owner.usable_legs - 1)
 			if(owner.stat < UNCONSCIOUS)
-				owner.emote("scream")
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>Your [name] is too damaged to function!</span>")
-		if(BODYPART_DISABLED_PARALYSIS)
-			if(owner.stat < DEAD)
-				to_chat(owner, "<span class='userdanger'>You can't feel your [name]!</span>")
+				to_chat(owner, "<span class='userdanger'>Your lose control of your [name]!</span>")
+	else if(!bodypart_disabled)
+		owner.set_usable_legs(owner.usable_legs + 1)
 
 
 /obj/item/bodypart/r_leg/digitigrade
@@ -326,11 +440,13 @@
 	icon_state = "alien_r_leg"
 	px_x = 0
 	px_y = 0
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 100
 	animal_origin = ALIEN_BODYPART
 
 /obj/item/bodypart/r_leg/devil
-	dismemberable = 0
+	dismemberable = FALSE
+	can_be_disabled = FALSE
 	max_damage = 5000
 	animal_origin = DEVIL_BODYPART