Trouble with undefined variables

ID:868265
 
Jul 13 2012, 12:03 pm
Keywords: error, src, undefined, usr, var
(See the best response by LordAndrew.)
Code:
mob
    player
        icon='player.dmi'
        icon_state="suit"
        var
            cNavSkill = 55//navigator skill on scale 01-100

proc
    checkNav()
        //generate random placement errors
        var/navErrorX = rand (1,100)
        var/navErrorY = rand (1,100)
        
        //adjust x-dir error by cNavSkill
        navErrorX -= src.cNavSkill
        navErrorY -= src.cNavSkill


Problem description:
I get a "src.cNavSkill: undefined var" on both lines where it's called in the proc. It happens regardless of whether I use "usr.cNavSkill" or "src.cNavSkill" to call the variable in the proc. I've been reading a lot lately on how I should normally be using "src" instead of "usr" to call variables, and it was while I was changing variable definitions around that I got this error.

I only want this variable assigned to "player" type mobs. It must be an obvious thing, but I sure can't seem to figure it out. I guess I don't understand variables well enough yet.
Jul 13 2012, 12:05 pm
Based on the tabbing, you've made checkNav() a global procedure. Just tab it under /mob/player like you have for the variable declaration and it'll work.
Jul 13 2012, 12:36 pm
That appears to have worked, Lord Andrew.

So is there a way for me to call a player.var to a global proc?
Jul 13 2012, 12:44 pm
In response to OrionBPG
Best response
Indeed. Simply allow the global procedure to accept an argument (in this case you'd want it to accept a /mob/player.)

mob
    player
        var
            chocolateDonuts = 0

        Login()
            ..()

            giveDonuts(src, 10)

            src << "You have [chocolateDonuts] chocolate donuts!"

proc
    giveDonuts(mob/player/m, amount)
        // If for instance we tried to supply something that wasn't a /mob/player, just return the procedure and do nothing.
        if(!istype(m)) return

        m.chocolateDonuts += amount
Jul 13 2012, 12:47 pm
 
proc/stuff()
    src<<"Hi!"

This makes the world see the text. "Hi!". So no one else can see it. Basically, src is the world. If you say src.cNavSkill, that's the world's var, which doesn't exist.

Now if you put it somewhere else:
var/cNavSkill

You would get no errors, but nothing would happen to the player, because the variable is assigned to the world.
Jul 13 2012, 1:19 pm
Ahh. Ok, now I get it.

Thanks to both of you for the education. I have a better feel for variable scoping now. Looks like my variable tree will need some re-arranging.