Why would pressing the play button delete and recreate a MonoBehaviour?

Questions & Answers
1

So I have a MonoBehaviour with a List<> as a public member. Whenever I hit the play button, the MonoBehaviour calls its destructor and is reinitialized. I have a function in the Awake() command that checks for if the List is null and initializes it to an empty list, but it seems the list is always set to null .

I have some ContextMenu commands that modify the list and return its state. I can use these commands after Play is pressed and they all work fine. There are currently no calls to any of these context commands in aside from the one call in Awake(). I’ve included some of the relevant code here.

`
public class DinoSpawner : MonoBehaviour {

public List<DinoWave> waveList;
static DinoSpawner instance = null;

public static DinoSpawner Instance { get
{
    if (!(instance == null))
        return instance;
    instance = (DinoSpawner)UnityEngine.Object.FindObjectOfType(typeof(DinoSpawner));
    if (instance == null)
        Debug.LogError("Couldn't find an instance of DinoSpawner!");
    return instance;
}}

~DinoSpawner()
{
    Debug.Log("Destroyed spawner");
}

// Use this for initialization
void Awake () {
    Debug.Log("Created spawner");
    ResetWaveList();
    instance = this;
}

// Update is called once per frame
void Update () {
    timeUntilNextWave -= Time.deltaTime;
    int counter = 0;
    while (timeUntilNextWave < 0 && !IsFinished())
    {
        StartNextWave();
        counter++;
        if (counter > 20)
            Debug.LogError("Infinite loop!", this);
    }
    for (int i = 0; i < currentWave; ++i)
    {
        DinoWave wave = (DinoWave)waveList*;*

if (wave != null)
wave.Update();
}

  • }*
    [ContextMenu(“GetNumWaves”)]
    public void GetNumWaves()
    {
    if (waveList != null)
    Debug.Log(“There are currently " + waveList.Count.ToString() + " waves.”);
    else
    Debug.Log(“Wave list not initialized!”);
    }
    [ContextMenu(“Add Wave”)]
    public void AddWave()
    {
    ResetWaveList();
    waveList.Add(new DinoWave());
    }
    [ContextMenu(“Reset Wave List”)]
    public void ResetWaveList()
    {
    if (waveList == null)
    {
    Debug.Log(“Resetting wave list”);
    waveList = new List();
    }
    }
    [ContextMenu(“Clear Waves”)]
    public void ClearWave()
    {
    Debug.Log(“Manually clearing wave list”);
    waveList.Clear();
    currentWave = 0;
    }
    `
    I’m just getting started in Unity so there could be something simple that I missed, but I couldn’t find anything when I searched.
2

I would also not use ~XXX() as unity manages stuff itself too and you can get pretty unpredictable results.

If you want to track destruction of unity objects, then MonoBehaviour and alike offer OnDestroy() for example.

3

I guess your problem is that your DinoWave class is not serializeable. Unity always saves and restores the scene when entering playmode. You can delete and change objects at runtime as you like, but everything gets reverted if you stop. Only things that are serializeable are actually saved.

Try to add a [System.Serializable] attribute to your DinoWave class, that should help :wink:

also you don’t need to derive from UnityEngine.Object except you want some of the inherited stuff like hideflags or something like that.