Small container transfer rate change improvements (#18780)

* Avoid extraneous warning on `set_APTFT()` cancel

* Add `set_APTFT()` success feedback message

* Standardize `possible_transfer_amounts`

* Cryptic var names begone

* Unhardcode "It will transfer X units" examine note

* Fix grammar

code/modules/reagents/reagent_containers.dm

@@ -5,6 +5,7 @@
 	icon_state = null
 	w_class = WEIGHT_CLASS_TINY
 	var/amount_per_transfer_from_this = 5
+	var/visible_transfer_rate = TRUE
 	var/possible_transfer_amounts = list(5,10,15,25,30)
 	var/volume = 30
 	var/list/list_reagents = null
@@ -25,7 +26,9 @@
 	var/default = null
 	if(amount_per_transfer_from_this in possible_transfer_amounts)
 		default = amount_per_transfer_from_this
-	var/N = input("Amount per transfer from this:", "[src]", default) as null|anything in possible_transfer_amounts
+	var/new_transfer_rate = input("Amount per transfer from this:", "[src]", default) as null|anything in possible_transfer_amounts
+	if(!new_transfer_rate)
+		return
 
 	if(!usr.Adjacent(src))
 		to_chat(usr, "<span class='warning'>You have moved too far away!</span>")
@@ -34,8 +37,8 @@
 		to_chat(usr, "<span class='warning'>You can't use your hands!</span>")
 		return
 
-	if(N)
-		amount_per_transfer_from_this = N
+	amount_per_transfer_from_this = new_transfer_rate
+	to_chat(usr, "<span class='notice'>[src] will now transfer [amount_per_transfer_from_this] units at a time.</span>")
 
 /obj/item/reagent_containers/AltClick()
 	set_APTFT()
@@ -100,8 +103,9 @@
 /obj/item/reagent_containers/examine(mob/user)
 	. = ..()
 
-	// Food has no valid possible_transfer_amounts, and we don't want to show
-	// this message on examining food.
+	if(visible_transfer_rate)
+		. += "<span class='notice'>It will transfer [amount_per_transfer_from_this] unit[amount_per_transfer_from_this != 1 ? "s" : ""] at a time.</span>"
+
+	// Items that have no valid possible_transfer_amounts shouldn't say their transfer rate is variable
 	if(possible_transfer_amounts)
-		. += "<span class='notice'>It will transfer [amount_per_transfer_from_this] unit[amount_per_transfer_from_this > 1 ? "s" : ""] at a time.</span>"
 		. += "<span class='notice'>Alt-click to change the transfer amount.</span>"

code/modules/reagents/reagent_containers/applicator.dm

@@ -6,6 +6,7 @@
 	item_state = "mender"
 	volume = 200
 	possible_transfer_amounts = null
+	visible_transfer_rate = FALSE
 	resistance_flags = ACID_PROOF
 	container_type = REFILLABLE | AMOUNT_VISIBLE
 	temperature_min = 270

code/modules/reagents/reagent_containers/glass_containers.dm

@@ -240,7 +240,7 @@
 	desc = "A baggie. Can hold up to 10 units."
 	icon_state = "baggie"
 	amount_per_transfer_from_this = 2
-	possible_transfer_amounts = 2
+	possible_transfer_amounts = null
 	volume = 10
 	container_type = OPENCONTAINER
 	can_assembly = 0

code/modules/reagents/reagent_containers/hypospray.dm

@@ -86,7 +86,7 @@
 	name = "combat stimulant injector"
 	desc = "A modified air-needle autoinjector, used by support operatives to quickly heal injuries in combat."
 	amount_per_transfer_from_this = 15
-	possible_transfer_amounts = list(15)
+	possible_transfer_amounts = null
 	icon_state = "combat_hypo"
 	volume = 90
 	ignore_flags = 1 // So they can heal their comrades.
@@ -104,7 +104,7 @@
 	item_state = "autoinjector"
 	belt_icon = "autoinjector"
 	amount_per_transfer_from_this = 10
-	possible_transfer_amounts = list(10)
+	possible_transfer_amounts = null
 	volume = 10
 	ignore_flags = TRUE //so you can medipen through hardsuits
 	container_type = DRAWABLE
@@ -151,7 +151,6 @@
 	desc = "Rapidly stimulates and regenerates the body's organ system."
 	icon_state = "stimpen"
 	amount_per_transfer_from_this = 50
-	possible_transfer_amounts = list(50)
 	volume = 50
 	list_reagents = list("stimulants" = 50)
 
@@ -168,7 +167,6 @@
 	desc = "After a short period of time the nanites will slow the body's systems and assist with bone repair. Nanomachines son."
 	icon_state = "bonepen"
 	amount_per_transfer_from_this = 30
-	possible_transfer_amounts = list(30)
 	volume = 30
 	list_reagents = list("nanocalcium" = 30)
 

code/modules/reagents/reagent_containers/syringes.dm

@@ -10,7 +10,7 @@
 	icon_state = "0"
 	belt_icon = "syringe"
 	amount_per_transfer_from_this = 5
-	possible_transfer_amounts = list()
+	possible_transfer_amounts = null
 	volume = 15
 	sharp = TRUE
 	var/busy = FALSE