Using a variable that's been set to null

02-24-2005, 08:59 PM

This is a slightly advanced question.

I'm working with a periodic trigger that deals with Unit Groups. Naturally, I want to do take care to prevent memory leaks.

The problem is that once a Unit Group has been destroyed or set to null, it no longer has it's default value. So, a trigger that looks like this:

Code:

Awesome Presence
    Events
        Time - Every 5.00 seconds of game time
    Conditions
    Actions
        Unit Group - Pick every unit in [color=orange]ug_AwesomePresenceCasters[/color] and do (Actions)
            Loop - Actions
                If (All Conditions are True) then do (Then Actions) else do (Else Actions)
                    If - Conditions
                        ((Picked unit) is alive) Equal to True
                    Then - Actions
                        Set [color=orange]u_CurrentUnit[/color] = (Picked unit)
                        Unit Group - Remove all units from [color=orange]ug_StunnedUnitGroup[/color]
                        Unit Group - Remove all units from [color=orange]ug_AwesomePresenceGroup[/color]
                        Set SpecialEffectIndex = 0
                        Unit Group - Add all units of (Units within [color=orange]i_AwesomeRadius[/color] of (Position of [color=orange]u_CurrentUnit[/color]) matching (((Owner of [color=orange]u_CurrentUnit[/color]) is an ally of (Owner of (Matching unit))) Equal to False)) to [color=orange]ug_AwesomePresenceGroup[/color]
                        [color=green]// Do Some stuff to those units[/color]
                        Custom script:   call DestroyGroup(udg_ug_AwesomePresenceGroup)
                        Custom script:   set udg_ug_AwesomePresenceGroup = null
                    Else - Actions
       [color=green] ... (more code, unimportant for this example)[/color]

Will stop working after one iteration. The reason for this is the destruction of the ug_AwesomePresenceGroup Unit Group.

I currently have a way around it that I don't like - i can first Set ug_AwesomePresenceGroup to a Unit Group of some kind, and then work with it from there. Is there an easier way around my problem?

02-24-2005, 09:24 PM	#2
Guest	You can't use a non-initialized unit group ( i.e. destroyed or null ). If you examine the map scripts you will see every unit group you use has to be initializaed. Use this to do so: set unitgroupvar = CreateGroup()

02-24-2005, 10:18 PM	#3
Guest	Create another group variable with no unit in it that you won't use, call it "group_null" for example Set unitgroupvar = group_null should work, as defaults unit group consider 'no units' rather as 'null'

02-25-2005, 02:25 AM

aaero

Thanks Sabugostorm - that helps immensely!

BadFurDay - I don't think that method works, but it might just be my fault. According to the behavior I observed when I tried your solution, I think when you set two objects equal to one another, it considers them exactly the same (from a programming perspective, it points to the same memory location). Thus, when you set the object to null, you can't use your blank unit group anymore.