Destroy(this)???

Unity Engine
1

Hi,
Suppose I have a List of objects of a class type, and IN that class, I create an Update() function inside the class with code in it so that each object or list of objects destroys itself 5 seconds after construction. Wouldn’t making Destroy(this) possible be a good idea for something like that? What would also REALLY be a good idea is to have a way where code could be written so that the list ‘removes’ each element after 5 seconds since destroying the element I believe makes it null or missing.

2

Could you add the object to the list when it is spawned & have a timer on the object that says after 5 seconds remove it from list A & add it to list B? Or are you talking about pooling?

3

Give the “Manager” Class that contains the List a public static Method for Adding and Removing Items from that list.
On the Gamobjects, you call said Methods on Start and OnDestroy to either add or remove.

4

Example of what garrido86 means (errors are expected as notepad++ does not have intellisense):

public class DestroyMe : MonoBehaviour
{
    void Start()
    {
        Manager.Add(this);
    }
   
    void Update()
    {
        // Check some arbitrary timer and then
        Destroy(gameObject);
    }
   
    void OnDestroy()
    {
        Manager.Remove(this);
    }
}

public static class Manager : MonoBehaviour
{
    private List<DestroyMe> _list = new List<DestroyMe>();
   
    public static void Add(DestroyMe thing)
    {
        _list.Add(thing);
    }
   
    public static void Remove(DestroyMe thing)
    {
        _list.Remove(thing);
    }
}

However, depending on what you do with the items, pooling might be a better idea: http://unity3d.com/learn/tutorials/modules/beginner/live-training-archive/object-pooling

1 Like
5

Do all of that. Except don’t make the methods static.

It’s also worth pointing out that Destroy takes an optional second parameter. This is a float that specifies the time to destruction. Calling it once in Start beats calling it in Update.

1 Like
6

Updated code as per BoredMormon’s recommendations:

public class DestroyMe : MonoBehaviour
{
    private object _manager;
 
    void Start()
    {
        _manager = (Manager)FindObjectOfType(typeof(Manager));
        _manager.Add(this);
     
        Destroy(gameObject, 5.0f);
    }
 
    void OnDestroy()
    {
        _manager.Remove(this);
    }
}

public class Manager : MonoBehaviour
{
    private List<DestroyMe> _list = new List<DestroyMe>();
 
    public void Add(DestroyMe thing)
    {
        _list.Add(thing);
    }
 
    public void Remove(DestroyMe thing)
    {
        _list.Remove(thing);
    }
}

To be clear, I have let out quite a lot of null check and potential error handling out of this code, so make sure to not use it 1:1 without adding it as it can save you a lot of headaches later on. This also ensures you’ll work with the code so you learn it well :slight_smile:

1 Like