Cannot read null.Rank >.< in Developer Help

ID:264306
 
Jan 5 2009, 6:01 pm
Code:
mob/Player
    proc
        Village_Members(village)
            var/list/villagers = new
            for(var/mob/M)
                if(M.Village == village) villagers+=M
            return villagers


    Owners/verb
        Define_Kage()
            set category = "Owner"
            var/list/Villages[] = list("Leaf"="Hokage","Sand"="Kazekage","Mist"="Mizukage",\
                                 "Cloud"="Raikage","Rock"="Tsuchikage","Rain"="Amekage",\
                                 "Sound"="Otokage","Waterfall"="Waterfall Hero")
            var/V = input("Which village?","") in Villages
            if(Kages["[Villages[V]]"] != "<i>none</i>")
                switch(alert("There currently is a [Villages[V]]. Replace?","Confirmation","No","Yes"))
                    if("No") return
            var/mob/M = input("Promote who to [Villages[V]]?","Define [Villages[V]]") in Village_Members(V)
            M.Rank = "[Villages[V]]"
            Kages["[Villages[V]]"] = M
            world<<"<center>[M] is now the [Villages[V]]</center>"
            Save_Lists()


Problem description:

runtime error: Cannot modify null.Rank.
proc name: Define Kage (/mob/Player/Owners/verb/Define_Kage)
usr: Mizukouken Ketsu (/mob/Player)
src: Mizukouken Ketsu (/mob/Player)
call stack:
Mizukouken Ketsu (/mob/Player): Define Kage()
#1 Jan 5 2009, 6:07 pm
Oh wow nevermind... I figured out what was going on. xD My 'Village' var wasn't equalling the village selection from the list :) So the Village_Members() proc was returning an empty list (aka null).
#2 Jan 5 2009, 6:09 pm
Add a cancel button to the input so it accepts null values.
var/mob/M = input("Promote who to [Villages[V]]?","Define [Villages[V]]") as null|anything in Village_Members(V)


Also, you should always do a safety check after an input() like so:

if(M)
#3 Jan 5 2009, 6:42 pm
You really should use datums to handle villages, so much cleaner.
#4 Jan 5 2009, 6:48 pm
In response to Andre-g1 (#2)
For others, it might help, but not for me :) Even if they leave, they'll still get the rank and when they log in again, they'll get all the benefits :) Behold! The power of lists! >:O