list errors

ID:178592
 
Apr 25 2002, 9:38 am
Now that I am a bit more comfortable with asking for help I was thinking about past errors I got that either made me mad or made me scratch my head (Mostly stuff I do in other langs that I try to convert to DM)


var/n
n/var/z
var/n/p[10]

So if that was c++ code it would read

struct n {
int z;
};
n p[10];

Now here is the problem I get:

How would I refer to z in p?
if you do:
p[1].z=1 // error
(p[1]).z=1 // error

Any ideas?

Apr 25 2002, 9:46 am
The problem you've got is that p[1] is known to DM only as an item in the list--DM doesn't know what type it is, because it could be a number, a string, a datum, a type path, another list, or null.

The solution here is to type cast:
var/mydatum/item=P[1]
usr << item.z

Lummox JR
Apr 25 2002, 9:48 am (Edited on Apr 25 2002, 9:54 am)
In response to Lummox JR
Ya thats what I did in my code but I was just hopeing I was typing something wrong (As you can prolly tell I hate declareing more vars than needed)

thanks.


I wonder if I could do p[1]:z
Apr 25 2002, 9:57 am
In response to Winbiko
nope I cant I stillg the same error.



//BEGIN CODE
var/n
n/var/z

mob.var/n/p[10]

mob.verb.test()
usr:p[1]:z =1
usr << usr:p[1]:z


//END CODE


loading tester.dme
tester.dm:7:error: :: expected end of statement
tester.dm:8:error: :: expected end of statement

tester.dmb - 2 errors, 0 warnings (double-click on an error to jump to it)
Apr 25 2002, 10:09 am
In response to Winbiko
Winbiko wrote:
nope I cant I stillg the same error.



//BEGIN CODE
var/n
n/var/z

mob.var/n/p[10]

mob.verb.test()
usr:p[1]:z =1
usr << usr:p[1]:z


//END CODE

Did you not read Lummox's post? He just told you you need to type cast the list item as a mob to reference its variables, and even gave you an example. Constructs such as "usr:p[1]:z" just isn't going to cut it. This barely even looks like BYOND code.
Apr 25 2002, 10:11 am
In response to Skysaw
oh.

See : works different than . I am still trying to get that. Sorry if I offened you.
Apr 25 2002, 10:20 am
In response to Winbiko
Winbiko wrote:
oh.

See : works different than . I am still trying to get that. Sorry if I offened you.

No, it has nothing to do with period vs. colon. Let me try to clear this up.

If p[1] contains a mob, and you want the value of z of that mob, you can't use this: p[1].z

List items simply can't be used as direct references this way. You need an interim variable:

var/mob/this_mob = usr.p[1]
this_mob.z = 1
usr << this_mob.z

sorry if I sounded harsh
Apr 25 2002, 10:22 am
In response to Skysaw
I understood that. I was just seeing if there was another way.
Apr 25 2002, 10:31 am
In response to Lummox JR
How would you edit p[1].z ?

sense that halfway var isnt a pointer
Apr 25 2002, 10:35 am
In response to Winbiko
Winbiko wrote:
How would you edit p[1].z ?

sense that halfway var isnt a pointer

Actually it is--if p[1] is a reference to a datum, then this should work:
var/n/item=p[1]
++n.z

Where you can get tripped up, though, is with non-datums. If you use a string or a number within the list itself, changes you make to a copy won't be reflected in the list.

Lummox JR
Apr 25 2002, 10:36 am
In response to Winbiko
Winbiko wrote:
How would you edit p[1].z ?

sense that halfway var isnt a pointer

But it is! :) Actually it's a reference, which is practically the same thing as a pointer.

var/mob/M = p[1]
M.z = 2

Now p[1].z = 2
Apr 25 2002, 10:39 am
In response to Shadowdarke
so how would you make it not a reference? (just wondering) like if you wanted to copy a var but not point to it?
Apr 25 2002, 10:51 am
In response to Winbiko
You would need to create your own copy routine. Get the s_admin library and examine the carboncopy verb (exact verb name may vary) for an excellent example.