trying a pick&buy thing

ID:144060
 
Apr 13 2007, 1:39 am
Code:
obj 
    wand
        icon='items.dmi'
        icon_state="wand"
        verb
            Examine()
                set src in usr.contents
                usr<<"This appears to be a wand; [src.core] core, with [src.power] power"
    Wand_Stand
        icon='items.dmi'
        icon_state="wands"
        verb
            buy_wand()
                set src in oview(1)
                var/obj/wand/W
                usr.Choice=input("Wand","Wand core",usr.Choice) in list("Unicorn Hair","Dragon Heart-String","Hippogriff Feather","Phoenix Tail-Feather")
                usr.Galleons-=7
                W.core=usr.Choice
                W.power=rand(5,15)
                usr.contents+=W
                usr<<"You just bought a wand."


Problem description:
runtime error: Cannot modify null.core.
proc name: buy wand (/obj/Wand_Stand/verb/buy_wand)
usr: VolksBlade (/mob/male)
src: Wand Stand (/obj/Wand_Stand)
call stack:
Wand Stand (/obj/Wand_Stand): buy wand()

while you guys are helping me with that ill make the coding invisible to the dream maker, and continue with other things i need to add into my game.

Apr 13 2007, 2:41 am
Your code is pretty messed up. I really recommend reading the resources found here.

For your main problem at hand - W is never actually initialized or set to any value, therefore its null. It isn't actually holding an object reference; typecasting only lets the compiler know what is going to be in the var, but typecasting doesn't set or affect the var in any way. You need to set that var to an object, in your case you'd want a new freshly made object.