Arguments Arguments Arguments ....!

ID:157273
 
Apr 9 2010, 9:49 pm
well, some things about arguments for a proc is really bugging me.

for instance
proc/AddVar(var/a,var/b)
 a+=b // does this change the actual value of a?
 return a

//consider that proc in mind
proc/TestAdd()
 var/x=10
 var/y=20
 //AddVar(x,y) // wat will this result into? 10 or 30 ?
 //x=AddVar(x,y) this will result in 30
 
 world << "Yay x variable has the value [x]"




Apr 9 2010, 11:03 pm
Run it and see.

But I'll spare you the effort: var/x will have the value 10, a will have the value 30. Values in DM are passed 'by value' - that means that they're copied into the arguments. So the 'var/a' in proc/AddVar() is a variable specific to AddVar, and it's just set to the same value as var/x when AddVar is called.

Important caveat: Objects in DM are references to that object. So a var/obj/o isn't the actual object, it's a pointer to that object. When that is passed by value, the same object is being referenced. So this:

testobj
    var/a

proc/AddTest(var/testobj/k)
    k.a+=10

proc/Test()
    var/testobj/test
    test.a = 0
    AddTest(test)
    world << test.a


will output 10.
Apr 10 2010, 7:57 am
In response to Jp
Thank You :)
The reason I asked that was to know if there was any difference between AddVar(var/a,var/b) and AddVar(a,b) ?

because your previous ' Values in DM are passed 'by value' '
does not seem applicable to in AddVar(a,b).
Apr 10 2010, 3:34 pm
In response to Quixotic
Those are the same procedure definitions.

proc/AddVar(var/a, var/b)
proc/AddVar(a, b) //These are the same!


It's just syntactic sugar that lets you leave out the 'var' statement
Apr 11 2010, 4:49 pm
In response to Jp
o.O
Are you also right about lists?
ListRem() // verb
        var/list/K=list("J","p") // ru wrong here ?
        ListRemoveAll("p",K,1)
        src<<"/----------"
        for(var/L in K)
            src<<"-[L]-"
        src<<"----------\\"
ListRemoveAll(Object,list/List) // removes all var/Objects in list
        if(isnull(List))    return null
        for(var/K in List)
            if(K==Object)   List.Remove(K)
        return List

I dont get this right.If it was passing values only, it should ListRemoveAll not remove it from the list.But running that - it does remove.
so the output is only "-J-".
Apr 11 2010, 5:11 pm
In response to Quixotic
Only strings and numerical values are passed by value. Everything else is passed by reference.
Apr 11 2010, 9:07 pm
In response to Garthor
Thank You