src, usr and M. in Developer Help

ID:147815
 
Nov 12 2003, 6:38 pm (Edited on Nov 12 2003, 6:46 pm)
Now, to the best of my knowledge, src is the bullet, usr is the person that fired the bullet, and M is the mob the bullet bumped.
                Fire()
                    usr.projectile(new/obj/bullet(usr.loc),usr.dir,10)

mob
    proc
        projectile(obj/projectile,var/dir,var/delay)
            sleep(1)
            walk(projectile,dir)
            sleep(delay)
            del(projectile)

obj
    bullet
        icon='goldenbullet.dmi'
        density=1
        Bump(mob/M)
            if(istype(M,/mob/characters))
                if(M.armored == 1)
                    var/damage = rand(1,15)
                    damage += usr.strength
                    M.MP -= damage
                    M.Death()
                    del(src)
                    return
                var/damage = rand(1,15)
                damage += usr.strength
                M.HP -= damage
                M.Death()
                del(src)
            if(istype(M,/mob/enemy))
                var/damage = rand(1,15) + usr.strength
                M.HP -= damage
                M.Death()
                del(src)
            else
                return
            del(src)

I fail to see the problem, but it's obviously because usr is null.

runtime error: Cannot read 0.strength
proc name: Bump (/obj/bullet/Bump)
source file: Objects.dm,1160
usr: 0
src: the bullet (/obj/bullet)
call stack:
the bullet (/obj/bullet): Bump(the guard (/mob/enemy/Guard))
#1 Nov 12 2003, 6:54 pm
Usr is null because you're not supposed to use usr in procs. You'll need to give the bullet itself some variable that keeps track of who fired it.
#2 Nov 12 2003, 6:58 pm
Expect a visit from our local caveman. :)

Bump() is one of the many procs that don't support usr. You should send the usr into the proc from the verb.
#3 Nov 12 2003, 7:10 pm
In response to Jon88 (#1)
Bah, I'm driving myself nuts.
I'm drawing a blank, where would I define the user of the verb for later use?
#4 Nov 12 2003, 7:16 pm
In response to Enigmaster2002 (#3)
On your bullt obj just make a mob type variable(var/mob/owner) and set it to the usr when fired. Then just check the shooter stats from that variable. :)
#5 Nov 12 2003, 9:57 pm
The correct way to set the owner of a projectile is to use a var belonging to it. It's best to do so when you create the projectile, by sending usr (if a verb fires it) as a second argument.
obj/projectile
  var/mob/owner
  density = 1

  New(newloc, mob/firedby)
    owner = firedby
    loc = firedby.loc
    walk(src, firedby.dir, 0)

Lummox JR
#6 Nov 12 2003, 10:30 pm
In response to Lummox JR (#5)
It's still bellyaching about a null usr...
<dm>
Fire()
usr.projectile(new/obj/bullet(usr.loc),usr.dir,10,usr)

mob
proc
projectile(obj/projectile,var/dir,var/delay,mob/firedby)
shooter = firedby
sleep(1)
walk(projectile,dir)
sleep(delay)
del(projectile)

obj
bullet
icon='goldenbullet.dmi'
density=1
var/mob/shooter
Bump(mob/M)
if(istype(M,/mob/characters))
if(M.armored == 1)
var/damage = rand(1,15)
damage += shooter.strength
M.MP -= damage
M.Death()
del(src)
return
var/damage = rand(1,15)
damage += shooter.strength
M.HP -= damage
M.Death()
del(src)
if(istype(M,/mob/enemy))
var/damage = rand(1,15) + shooter.strength
M.HP -= damage
M.Death()
del(src)
else
del(src)
del(src)
#7 Nov 12 2003, 10:44 pm
In response to Enigmaster2002 (#6)
If Fire() a proc? Next time please let us know which line the runtime error occurs on.
#8 Nov 12 2003, 10:55 pm
In response to Jnco904 (#7)
Ack, forgot to post it.
<dm>
obj
bullet
icon='bullets.dmi'
icon_state = "bullet"
density=1
var/mob/shooter
Bump(mob/M)
if(istype(M,/mob/characters))
if(M.armored == 1)
var/damage = rand(1,15)
damage += shooter.strength //This line...
M.MP -= damage
M.Death()
del(src)
return
var/damage = rand(1,15)
damage += shooter.strength //This line...
M.HP -= damage
M.Death()
del(src)
if(istype(M,/mob/enemy))
var/damage = rand(1,15) + shooter.strength //And this line.
M.HP -= damage
M.Death()
del(src)
else
del(src)
del(src)

runtime error: Cannot read null.strength
proc name: Bump (/obj/bullet/Bump)
source file: Objects.dm,1165
usr: 0
src: the bullet (/obj/bullet)
call stack:
the bullet (/obj/bullet): Bump(the guard (/mob/enemy/Guard))
#9 Nov 12 2003, 11:44 pm
In response to Enigmaster2002 (#8)
I see a problem here:
mob
    proc
        projectile(obj/projectile,var/dir,var/delay,mob/firedby)
            shooter = firedby
            sleep(1)
            walk(projectile,dir)
            sleep(delay)
            del(projectile)

"shooter = firedby" would be the equivelent of "src.shooter = firedby" and since the person firing is src in this instance it would set the shooters shooter var to the shooter(=D). I don't know how you didn't get a compile error, unless you made a shooter var for mobs also. Anyway, you need to set the projectiles shooter var "projectile.shooter = firedby", but since the base /obj type doesn't have a shooter var(which it shouldn't) you'll have to specify that it is a bullet in the arguements "projectile(obj/bullet/projectile,var/dir,var/delay,mob/firedby)".
#10 Nov 12 2003, 11:52 pm
In response to Jnco904 (#9)
Whew, thanks for the help, it finally works. I'm dumb this way.