Null exception

[Smokeynz]

ok tried the last alteration, but still seeing exceptions when the timer comes to run despawner.

if (actor is AiAircraft)
Timeout(despawntime, () =>
{
damageAiControlledPlane(actor);
});

i added a null check after the timeout but still problem exists

if (actor is AiAircraft)
Timeout(despawntime, () =>
{
if(actor != null) damageAiControlledPlane(actor);
});

basically I think the problem is the existance/ state of the object is different after aperiod than from when the timeout is called, ie the plane is just created.
When the destroy actually runs, the aircraft has already been detroyed by activivity or something else. despite anull check it throws an exception. So the null is not the right check, in the wrong place or other problem is causing issue.

However, I have noticed that the "on actor task completed" can have 1 ai interfere with another ai if the last path length crosses another ai path.
Which makes me wonder if there is some cross over in other areas.

any ideas anyone?

[Smokeynz]

Think this explains what I am seeing, 3. Don’t kill objects too soon.

http://codebetter.com/raymondlewalle...ses-in-vb-net/

But the problem for CLOD, the Onactorcreated creates an array of objects, actors which are part of play.
If you test those objects later, and they have been destroyed by play or despawning routines, they don't exist, so either the reference of "null" or the actor reference will throw an exception. For null there has to be an array member to state "are you null" .

So with that, incounting exceptions of objects with no reference, it may require double listing arrays. The game creates an internal onactorcreated, you might have to create a second array to test the actors condition upon.

Kinda a test of "are you alive" by comparing existance of that actor in both arrays. In play that actor meets its fate, is despawned or hangs around. In 2 of these you may incounter an object reference error if trying to clear the decks of clutter. With a second array "null" is not important, because you test against the array with array, not the "object actor" which may be automatically cleared from the onactorcreated array.

confused, i am.

if I am on the right track in this, we need a method to avoid object exception when dealing with object/actor tracking over the mission period. Considering that the base mission has potential to be 24/7

in summary

objects/actors can lose references to themselves so that even the "null" test has no reference. this thows an exception object without a reference.

[salmo]

SmokyNZ, I concur with you that there is something screwy with the actors that gives rise to null exceptions. I'm unsure what the cause is, but here's a code snippet from a script I'm working on. The CheckActors routine was working & keys.Count was returning the number of actor keys, then all of a sudden, it failed & now persistently returns zero even though there are actors in the mission.

public class Mission : AMission
{
private Dictionary<String, AiActor> allActors = new Dictionary<String, AiActor>();

    public override void OnPlaceEnter(Player player, AiActor actor, int placeIndex)
    {
CheckActors();
}

public void CheckActors()
{
        List<string> keys = new List<string>(allActors.Keys);
        sendChatMessageTo(-1, "Keys count=" + keys.Count.ToString(), null);
       // .......
    }

    private void sendChatMessageTo(int army, string msg, object[] parms)
    {   // send a chat message to all players in specified army (1=red; 2=blue)
        List<Player> Players = new List<Player>();
        // on Dedi the server:
        if (GamePlay.gpPlayer() != null)
        {
            if (GamePlay.gpPlayer().Army() == army || army == -1)
                Players.Add(GamePlay.gpPlayer());
        } //rest of the crowd
        if (GamePlay.gpRemotePlayers() != null || GamePlay.gpRemotePlayers().Length > 0)
        {
            foreach (Player p in GamePlay.gpRemotePlayers())
            {
                if (p.Army() == army || army == -1)
                    Players.Add(p);
            }
        }
        if (Players != null && Players.Count > 0)
            GamePlay.gpLogServer(Players.ToArray(), msg, parms);
    }
}

[FG28_Kodiak]

@Smokeynz
Could i see the complete Errormessage, please?

[Smokeynz]

@Kodiak, I've sent you the mission so you can see the error in real time.
Spawn in and sit on deck, shift tab and monitor logs.(or export logs)
let it run for about 40~50mins and you will see lots of the errors about that time.


@salmo, yeah it is possible reference lists of players or any object can fall foul of the reference problem.

A google of the exception object missing reference yeilds plently of people suffering the same problem with C#

I found 2 links(1 posted above), where point 3 of above is what happens here(I believe). I'm a bit limited in experience to diagnose C# work arounds, once I have the syntax I can work it out, but get one thing wrong and it fails.

anyway key thing, any object that has a reference that can disappear can no longer be tested with null as null reference requires an existance. we asume that null means nothing, but it actually seems to mean nothing of something, not something of nothing.

think i might go blow something up in bf3



smoke

[FG28_Kodiak]

Ok, the null exeption you get has nothing to do with your script, it's the underlying engine that causes this problem.

You get also an
=================================================
System.ArgumentOutOfRangeException:

Server stack trace:
bei System.ThrowHelper.ThrowArgumentOutOfRangeExceptio n()
bei Mission.TriggerProcessing(String shortName, Boolean active)
bei Mission.OnTrigger(Int32 missionNumber, String shortName, ...

for example you have a Array arr with 100 entries. so you can access the entries with arr[0]..arr[99] if you try arr[100] you will get this exeption.
In C# the first element of an Array has the index 0 and the last has count-1.

[Smokeynz]

Ok, cheers, will ignore main exception error

Out of range

So if I count the list entries first, then do count -1 as indexing range I should in theory avoid the out of range?