null.Add() ?

ID:264300
 
Dec 29 2008, 10:51 am (Edited on Dec 30 2008, 5:24 am)
Code:
mob
        var
        Stats
            Health
    New()
        ..()
        Health = new(100)

Stats
    var
        Value = 0
        maxValue = 0
    New(n)
        if(n)
            Value = n
            maxValue = n
    proc
        Add(n)
            Value = min(max(Value+n,1),maxValue)

obj/Jutsu/Sand_Manipulator
    icon = 'Sand Manipulator Jutsu.dmi'
    Sand_Tsunami
        icon_state = "Sand Tsunami"
        density = 1
        Bump(atom/A)
            var/mob/O = Owner
            if(ismob(A))
                var/mob/M = A
                var/dmg = O.Ninjutsu.Value*O.sandTsun
                M.Health.Add(-dmg)
                O.Dmg_Text(M,dmg,"Sand Tsunami")


Problem description:
Okay I read the whole guide thing on datums and I came up with a system like that. I figured I could use the Add() datum proc for subtraction as well. However when the obj bumps into a mob, it gives me the following runtime error.

runtime error: Cannot execute null.Add().
proc name: Bump (/obj/Jutsu/Sand_Manipulator/Sand_Tsunami/Bump)
usr: 0
src: Sand Tsunami (/obj/Jutsu/Sand_Manipulator/Sand_Tsunami)
call stack:
Sand Tsunami (/obj/Jutsu/Sand_Manipulator/Sand_Tsunami): Bump(Sand Clone (/mob/Clones/Sand_Clone))
Sand Tsunami (/obj/Jutsu/Sand_Manipulator/Sand_Tsunami): Move(Grass1 (9,4,1) (/turf/Terrains/Grass1), 8)

How is it null when I have it M.Health.Add()?
Dec 29 2008, 10:58 am
Do you have Health as a new instance or is it still null? 
Health = new
Dec 29 2008, 11:22 am (Edited on Dec 30 2008, 5:23 am)
In response to GhostAnime
Yeah sorry. Forgot to add that snippet.
mob
    New()
        ..()
        Health = new(100)


Updated OP.
Dec 30 2008, 5:24 am
Still need help >_>
Dec 30 2008, 5:43 am
Since Health is being initialized, the problem must be that although it's not null when the mob is first created, it's becoming null at a later point.

One culprit to look at might be your savefiles. If you have an old savefile it may be trying to load health directly into a var, while the datum it loads is null. If that is the case, then here is the solution: In Read(), after the default load, make sure the Health var is still valid and if not adjust it accordingly.

If it's not a savefile issue, I'd take a look around other parts of your code that may be manipulating mob.Health and see if maybe something is nulling it out.

Lummox JR
Dec 30 2008, 6:05 am
In response to Lummox JR
I'm using this in a test world where there is no savefiles going on. So it's not the savefile system.

I'm using a verb that creates a clone of myself and sets the clone's attributes (e.g. Health, Chakra, etc). Could that not be working properly?

mob/Clones/Sand_Clone
    density = 1
    New(loc,owner,dir)
        ..()
        name = "[owner]"
        dir = dir
        Owner = owner
        var/mob/O = Owner
        icon = O.icon
        flick("Sand Clone",src)
        Health = O.Health.Value/(8-O.sandClon/2)
        var/mob/T = O.Target
        Clone_AI(T,O)
Dec 31 2008, 1:56 am
In response to Mizukouken Ketsu
If Health is a datum, then why are you setting it to a number in New()?

This line:

Health = O.Health.Value/(8-O.sandClon/2)


Obviously results in a number, not a datum. Create the Health datum first, then set its Value variable to that instead?