Pointers?

ID:2841290
 
Dec 12 2022, 3:36 pm
(See the best response by Ter13.)
Code:
```
var value = 444

mob/Login()
    Example(&value)
    world << "value: [value]"

proc/Example(value)
    *value = 333
    Example2(&value)

proc/Example2(value)
    *value = 222
```


Problem description:

Trying to create something but having issues with pointers, so the reference/pointer to them is lost after a single proc call?

The above outputs value: 333 when I think it should return 222, however if I just pass the variable without & or * it causes it to output 
&NORTH and <prob[1].x>



var/smart_variables/sv = new

smart_variables
    var pref
    var list/refs
    New()
        refs = new/list(128)
        spawn()
            var tick        = world.tick_lag
            var ref, list/l
            for()
                sleep(tick)
                for(ref in refs)
                    if(!ref){continue}
                    world << "[ref[1]] vs [*ref[2]]"
                    if(*ref[2] != ref[1])
                        ref[1] = *ref[2]
                        switch(ref:len)
                            if(3)
                                call(ref[3])(ref[1])

proc/follow_changes(variable,function)
    sv.refs[++sv.pref] = list(*variable, &variable, /proc/Example)


Trying to create a datum that contains a list such as the pointer to the variable so I can loop and find if said variable's value has changed so that I may call a function.

Trying to create a better version of this

Dec 12 2022, 3:50 pm
Best response
Example's value parameter is already a pointer when you pass it to Example2, so you don't need to use &value when you pass it to Example2.

var value = 444

mob/Login()
    Example(&value)
    world << "value: [value]"

proc/Example(value)
    *value = 333
    Example2(value)

proc/Example2(value)
    *value = 222


This will perform as you expect.
Dec 12 2022, 3:53 pm
In response to Ter13
Ter13 wrote:
Example's value parameter is already a pointer when you pass it to Example2, so you don't need to use &value when you pass it to Example2.

Damn
Dec 12 2022, 4:10 pm
A good way to avoid trouble with pointers is to use a naming scheme to help remember. Prevacing the var name with p can be enough, like proc/Example(pvalue), to remind you it's a pointer.
Dec 31 2022, 9:52 am
As I understand it, that's because, with the way you had it before, you make a pointer to a pointer.

*value in Example2 accesses the variable 'value' in Example, which contains the pointer to the global variable 'value'.

So e.g. **value would access the global variable, and *value=222 changes the Example variable so it holds 222 instead of holding the pointer to the global 'value'.