I have a class, ControlFlagBehavior, which is the functional backend of another class, ControlFlag. For some reason, this class is exhibiting some very odd behavior. This is the class definition, with nothing changed or stripped out:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using UnityEngine;
public class ControlFlagBehavior : MonoBehaviour
{
public static ControlFlagBehavior Create(ControlFlag flag)
{
if (flag == null) throw new ArgumentNullException("flag");
var raq = Service.Provider.Current.GetService<ResourceAcquisitionService>();
var template = raq.GetPrefab("Ornaments/ControlFlagTemplate");
var obj = (GameObject)Instantiate(template);
var beh = obj.GetComponent<ControlFlagBehavior>();
beh.flag = flag;
return beh;
}
private ControlFlag flag;
public ControlFlag ControlFlag
{
get
{
return flag;
}
}
public GameController GameController
{
get
{
return flag.GameController;
}
}
public virtual void Start()
{
}
public virtual void Update()
{
float tlx, tly, tlz;
if (flag == null)
{
Debug.LogWarning("Flag null! Deleting gameObject...");
GameObject.Destroy(gameObject);
return;
}
flag.GetOrnamentLocation(out tlx, out tly, out tlz);
var pos = transform.position;
pos.x = tlx;
pos.y = tly + .03f;
pos.z = tlz;
transform.position = pos;
}
}
As you can see, flag is assigned only once, and it cannot be null. If flag is ever detected to be null, then an error message is logged and the GameObject and behavior are destroyed.
When I run the game, this all works fine. The prefab is found and instantiated, and the Update function correctly positions the GameObject. If you wait, however, then eventually "Flag null! Deleting gameObject..." is logged, and all of the ControlFlagTemplatess that were instantiated are deleted at the same time.
I have no idea why this is happening. According to the rules of the C# language, flag should be impossible to modify outside of the object. The only guess I can make is that some bug in the Unity engine or in the Mono garbage collector is prematurely collecting the ControlFlag object, despite the fact that it is referenced in the behavior (and, incidentally, in a few other places.)
A few notes: I have no untrusted code. I have not done anything with reflection. When I have multiple ControlFlag objects (each with their own ControlFlagBehavior) they are all set to null during the same frame.
So, why is this happening? More importantly, how do I fix it?
Thanks.
