List Index Out of Bounds?

ID:145834
 
Nov 26 2005, 1:55 pm
Code:
Deposit
    var/list/Veins

    New(Vein)
        Veins = new()
        ..()
        Veins += Vein

        var/rich   = round(rand(1, 3),1)
        var/size   = round(rand(5,25),1)
        var/list/Prev = list(Vein)
        var/list/Temp = list()
        for(size,size>0,size--)
            if(!Prev || !Prev.len) break
            for(var/i=1,i<=Prev.len,i++)
                if(pick(rich,0,0))
                    for(rich,rich>0,rich--)
                        for(var/n=8, n>0, n--)
                            if(!Prev || !Prev.len)
                                world.log << "No Prev!"
                                return
                            else
                                world.log << "[Prev.len] Prev!"
                            if(i > Prev.len)
                                world.log << "[i] > [Prev.len]!"
                                return
                            else
                                world.log << "[i] < [Prev.len]"
                            sleep(2)
                            for(var/p in Prev) world.log << p
                            var/turf/T = pick(oview(1,Prev[i]))
                            if(T && !T.contents.len)
                                var/obj/Vein/V = new(T, src)
                                Temp += V
                                break
                else
                    for(var/n=8, n>0, n--)
                        if(!Prev || !Prev.len)
                            world.log << "No Prev!"
                            return
                        else
                            world.log << "[Prev.len] Prev!"
                        if(i > Prev.len)
                            world.log << "[i] > [Prev.len]!"
                            return
                        else
                            world.log << "[i] < [Prev.len]"
                        sleep(2)
                        for(var/p in Prev) world.log << p
                        var/turf/T = pick(oview(1,Prev[i]))
                        if(T && !T.contents.len)
                            var/obj/Vein/V = new(T, src)
                            Temp += V
                            break
            Prev += Temp
            Temp = new()
        world.log << "DONE!"



obj
    Vein
        icon = 'grass.dmi'
        icon_state = "vein"

        var
            Deposit/Load

        New(Loc, Depo)
            if(istype(Depo,/Deposit)) src.Load = Depo
            else InitDeposit()
            ..()

        proc
            InitDeposit()
                var/Deposit/Depo = new(src)
                src.Load = Depo


Problem description: Create an instance of a Vein in the map and run. It goes along fine for a while, then spits out a List Index Out of Bounds error. I don't see how it could be out of bounds with all the checks before it. HELP!

Nov 26 2005, 2:55 pm
It will help narrow down the problem if you can find the line where this error is happening. Go to the Build menu, select Preferences, and turn on debugging info. Then recompile your game and run it. Once you find the line where the error is, please point it out.

Lummox JR
Nov 26 2005, 9:50 pm (Edited on Nov 26 2005, 10:44 pm)
In response to Lummox JR
Sorry, I thought you would have compiled and run the program. Also the checks should indicate where the problem is, since I wouldn't have them there if there wasn't. Line 61 is the main culprit, but line 42 also triggers it. Both are:

    var/turf/T = pick(oview(1,Prev[i]))


It's refering to i, which is a number less than the length of Prev but greater than 0, which doesn't refer to a null item in the Prev list, and is somehow out of bounds. I'm stumped.
Nov 27 2005, 7:36 am
In response to AZ0123
AZ0123 wrote:
    var/turf/T = pick(oview(1,Prev[i]))


Maybe it's not the Prev list that's the problem. Maybe it's pick()ing from the list returned by oview. Perhaps there are no turfs in the oview of whatever atom is returned by Prev[i].
Nov 27 2005, 7:42 am
In response to Jon88
It is picking from the list returned by oview(), that's what I want it to do. I don't think oview() would cause this error, and there are turfs all around the position where it spits out the error, so it can't be picking null.
Nov 27 2005, 7:48 am (Edited on Nov 27 2005, 7:56 am)
In response to AZ0123
AZ0123 wrote:
It is picking from the list returned by oview(), that's what I want it to do. I don't think oview() would cause this error, and there are turfs all around the position where it spits out the error, so it can't be picking null.

In the BYOND Beta I get this more descriptive error:
runtime error: pick() from empty list
proc name: New (/Deposit/New)
  source file: test.dm,50
  usr: null
  src: /Deposit (/Deposit)
  call stack:
/Deposit (/Deposit): New(Vein (/obj/Vein))
Vein (/obj/Vein): InitDeposit()
Vein (/obj/Vein): New(the tile (11,7,1) (/turf/tile), null)


Haven't yet figured out the cause of it, though. Nothing appears to be nearing the edge of the map.

Edit, found out the cause. Adding a check to see the Vein's loc, the loc of the one that crashes is another vein. This is because oview() returns a list of *all* objects, not just turfs. So one vein is being made inside another.

A way to fix this is by first making a temporary list full of the turfs returned by oview(), and then pick() from that. Also something you might want to do is check if there's already a vein in a spot where the creation of another vein is attempted.
Nov 27 2005, 7:54 am (Edited on Nov 27 2005, 8:45 am)
In response to Jon88
Oh! Thanks.

edit: I added a check after the pick() which fixes the error completely, but now I see my deposits are a bit larger than I was hoping for. Here's the check, which sees if T really is a turf, if not, it sets T to its loc, which is a turf in this basic setup.

if(!isturf(T)) T = T.loc