Null?

[13lade619]

Ok.. main question of this thread is:

How do you wrongfully have a "(null)" unit in run-time / in-game

I know that my problem is not in scripting/syntax because
a) the problem does not happen always.,
b) it is minimally replicable (i have not found the EXACT cause.)

So i figured it might be some weird conflict with something in my map.

The problem is this generated error message:

    function GetUnitId takes unit u returns integer
        debug if u==null then
        debug   call BJDebugMsg("|cFFFF0000Error using AIDS:|r Trying to get the id (inlines) of null unit.")
        debug   call BJDebugMsg(GetUnitName(u))
        debug endif
        return GetUnitUserData(u)
    endfunction

What i found out regarding probable errors on syntax:

    call GetUnitId(null) //This will correctly show the error message.


    local unit x = null
    call GetUnitId(x) //This will correctly show the error message.


    local unit x = null
    set x = CreateUnit(Player(0),'n00B',0,0,0)
    call KillUnit(x)
    call TriggerSleepAction(1) //A unit dies before getting processed, index goes through the recycler.
    call GetUnitId(x) //This NOT show any error... it proceeds normally.

    

    //however...

    local unit x //undeclared
    call GetUnitId(x) //This will STOP the entire thread.

    //But AFAIK, i'm not having this kind of error.

 

[kingkingyyk3]

It is normal. When compare a undeclared variables to a value, it will be paused. This teached you to declare a value for every variables, for less hassling.

 

[13lade619]

well yeah ok... but i'm looking for an answer to my first question though,..

why am i getting those error messages rarely.

EDIT: method 3 does not show any errors... i mistyped.

 

[Sevion]

Method 3 proceeds correctly because the unit is technically not null. Why? I don't know.

You can even try this test code:

scope test initializer initTest
    private function initTest takes nothing returns nothing
        local unit u = CreateUnit(Player(0), 'hfoo', 0, 0, 0)
        call SetUnitUserData(u, 1)
        call KillUnit(u)
        if ( u == null ) then
            call BJDebugMsg("ZOMG IT HAS TEH NULLZ!!!!")
        else
            call BJDebugMsg(I2S(GetUnitUserData(u)))
        endif
    endfunction
endscope

It'll correctly display 1.

However, if you change it to this:

scope test initializer initTest
    private function initTest takes nothing returns nothing
        local unit u = CreateUnit(Player(0), 'hfoo', 0, 0, 0)
        call SetUnitUserData(u, 1)
        call KillUnit(u)
        if ( IsUnitType(u, UNIT_TYPE_DEAD) ) then
            call BJDebugMsg("ZOMG IT BE DEAD! IT HAS NO DATA (lolz I jk I has lies. It has, but I haxxor you!)")
        else
            call BJDebugMsg(I2S(GetUnitUserData(u)))
        endif
    endfunction
endscope

It instead displays the long string I put in there.

 

[the Immortal]

> the unit is technically not null. Why? I don't know.
Because it exists. A dead unit is still an unit nonetheless. It just has one classification more- [ljass]UNIT_TYPE_DEAD[/ljass].

On your problem, try debugging more. Obviously you are sending a null unit (the reasons may be many - incorrectly indexed unit arrays, forgetting to clean/re-set a reused variable, etcetc..). If you are unable to find it manually (i.e. inspecting the code), put debug msgs with calling stack info wherever you use GetUnitId (err, <[ljass]if u == null then print("function XXX sending a null unit while enumerating units in range")[/ljass]> .. something like this), and try to reproduce the bug. It can't be that random. (hope you don't have lines like <[ljass]if GetRandomInt(0, 1) == 0 then set u = null[/ljass]> after all =D).

 

[13lade619]

<if u == null then print("function XXX sending a null unit while enumerating units in range")>

yeah i'm trying to find a way of doing it like that (automatically, not having to put that on all my code, that is my last resort)