First of Group - Dealing with null units

[SAUS]

I have a group that gets looped over periodically and needs to be able to have units be added and removed at any time. The group must persist each time.

I ran into an issue where one of the units exploded from a meat wagon so it got set to null. This causes problem with:

exitwhen picked == null

Is there any way to remove a null unit from a group?
Is there any way to check if there are still more units in the group that's not slow?

Or do I have to be super meticulous about removing the units as they die and whatnot?

I added a separate trigger to remove units from the group when they die, but I still eventually ran into the problem (basically the group just thinks it is empty forever - so adding units stops doing anything). It is hard to tell what happened that caused it.

 

[Ceday]

Easiest solution is using ForGroup instead of FirstOfGroup loop.

 

[SAUS]

Ya I forgot to mention that in there as well. The loop is every second, so I don't know how big of a deal it is for that. The number of units in the group won't be super large, but if null units get stuck in there, the loop could get bigger and bigger over time - hitting all the nulls for no reason.

Is there a way I can remove those null units when I find them? I could just have a quick check to see if the unit is equal to null and then remove it and return.

I suppose maybe I could also just have it check for when all the units are null. It would be very rare, I think, for the group to have units in it at all times for a very long time, so when it sees that they are all null, it can clear the whole group.

Another solution popped into my head haha. If I add the units that are not null to another group and then swap them like normal (clearing the old group), then it will remove all the null units that way.

Any other ideas?

 

[Ceday]

Using ForGroup won't cause any significant performance issues by itself for such high frequency.If you really really don't want to use it take a look at this.

http://www.hiveworkshop.com/forums/graveyard-418/snippet-unitll-209540/

 

[Wietlol]

Event: A unit dies.
Action: Remove unit from group.

Not good enough?
Then go for UnitLL.

 

[WaterKnight]

Or you can wrap/hook both the group and remove unit functions to keep track what the unit is registered for and make it quit in time.

 

[Xonok]

Can it actually return null for a unit in the group though? I don't think it really can, because the unit type is a reference. The type of the unit can be null, but I don't think the unit itself can be.

 

[BPower]

Go with ForGroup, when you want to use the group handle.

As an alternative you can create a linked list and interate over that.
Add units ( add a node to the list ) whenever you need it.
Remove invalid units handles via GetUnitTypeId(whichUnit) == 0. ( remove that node from the list )