My method doesn't save a variable value

Unity Engine
1

These methods do this: when i create a button, i initialize that and i give the class Object that contains all the info that the button needs. When i initialize the button objClass is not null (i can see it with Debug.Log()), but when i watch the variable on the inspector or i call a method like OnClickProposeExchange() the variable is null and i don’t understand why.

public void InitializeButton(bool isAnObjectButton, byte proprietor, Object objCharacts)
    {

        objClass = objCharacts;
        Debug.Log("obj class: " + objClass); //the output is NOT null here

        isObjButton = isAnObjectButton;

        owner = proprietor;

        Configure(); //here i don't use the value of objClass

        if (isAnObjectButton) // consider this always true
        { 
            if (owner != 0) // consider this always true
      
            {
                pnlToOpen.transform.Find("btnProposeExchange").GetComponent<Button>().onClick.AddListener(OnClickProposeExchange);                            
            }
         }
     }
     
void OnClickProposeExchange() // when i click this button
    {
        Debug.Log("On click propose exchange: classe:" + objClass); //now the output is null
        marketManager.OnCreatingExchange(objClass, owner); // and he gives me an error
    }
2

Are you sure you didn’t put this script on more than one GameObject, and perhaps that other copy is not correctly set up?

1 Like
3

Could you show the declaration of the variable? What’s its type, privacy, scope?

In Visual Studio, you can right-click a variable and say “find all references” to get a list of all code using that variable. This can be a helpful way to try to find something that you forgot was modifying it.

4

This script is on more than one gameobject, but when i set the listener but when I add the listener shouldn’t he call the method of his script?

5

public Object objClass;

Object is a mine class. This variable is declared inside the class, not the method.

I tried that function of Visual Studio but there’s nothing that modify the value

6

Even if every script sets itself as a listener, it might be difficult to correlate the Debug.Log on line 5 and the Debug.Log on line 25 to tell which ones are coming from the same script and which ones are coming from different scripts.

Wait, you declared your own class named Object? That’s very confusing.

Does it inherit (directly or indirectly) from MonoBehavior? A MonoBehaviour variable will compare as “equal” to null if gets destroyed, even if it’s not literally null.

7

Yes, “Object” inherits Monobehavior. The variable however is null because it gives me an error when i try to acces it.

8

Destroyed monobehaviours also give an error when you try to dereference them (although I think the error is worded differently compared to if they were truly null).

9

I’m pretty sure that only when you try to get at “Unity-ish” parts of them, such as .transform or .gameObject, or any of the in-built methods will it actually throw an error.

As far as your own instance fields, properties and functions in a Destroy()ed MB, hey, go nuts. They’re all still there until eligible for GC. It’s not GREAT practice, but nothing stops you from keeping a list of historically-used MBs once they’re destroyed, although I imagine you really have no way of knowing how much other referenced stuff is being kept from GC by that one reference!!