Question How to call the same method on all objects in the game scene ?

I have a script attached to three text boxes which need to update with the total number of resources held.

If I disable all but one and use the following code it all works fine:

FindObjectOfType<WindowGameResources>().UpdateResourceTextObject();

When there are more than one it doesn't work. Any idea how to make this work with multiple objects ?

Thanks.

 

It's hard to tell without seeing your code and understanding your object hierarchy.

Also a better description of your problem than "it doesn't work" would be helpful.

 

Hi Praetor,

I am attaching the relevant two scripts. GameResources is attached to an empty game object of the same name. The other script is attached to empty game objects within the canvas, each having a text child. The code doesn't work in the sense that the fields are not being updated. Thanks.

public class GameResources : MonoBehaviour
{

public enum ResourceType
{
apple,
orange,
lemon,
}


static Dictionary<ResourceType, int> ResourceAmountDictionary;


private void Awake()
{
Init();
}

public static void Init()
{
ResourceAmountDictionary = new Dictionary<ResourceType, int>();
foreach (ResourceType resourceType in Enum.GetValues(typeof(ResourceType)))
{
ResourceAmountDictionary[resourceType] = 0;
}

}

public static void AddResourceAmount(ResourceType resourceType, int amount)
{
ResourceAmountDictionary[resourceType] += amount;

FindObjectOfType<WindowGameResources>().UpdateResourceTextObject();
}

public static int GetResourceAmount(ResourceType resourceType)
{
return ResourceAmountDictionary[resourceType];
}

public class WindowGameResources : MonoBehaviour
{
[SerializeField] GameResources.ResourceType resourceType;
Text resourceText;

private void Start()
{
resourceText = transform.Find("Text").GetComponent<Text>();
UpdateResourceTextObject();
}

public void UpdateResourceTextObject()
{
resourceText.text =
GameResources.GetResourceAmount(resourceType).ToString();
}
}

 

Please use code tags in your post to make the code more readable, as described in this thread: https://forum.unity.com/threads/using-code-tags-properly.143875/

 

Code (CSharp):

1. public class WindowGameResources : MonoBehaviour
2. {
3.     [SerializeField] GameResources.ResourceType resourceType;
4.     Text resourceText;
5.  
6.     private void Start()
7.     {
8.         resourceText = transform.Find("Text").GetComponent<Text>();
9.         UpdateResourceTextObject();
10.     }
11.  
12.     public void UpdateResourceTextObject()
13.     {
14.             resourceText.text =
15.                 GameResources.GetResourceAmount(resourceType).ToString();
16.     }
17. }

Code (CSharp):

1. public class GameResources : MonoBehaviour
2. {
3.  
4.     public enum ResourceType
5.     {
6.         apple,
7.         orange,
8.         lemon,
9.     }
10.  
11.  
12.     static Dictionary<ResourceType, int> ResourceAmountDictionary;
13.  
14.  
15.     private void Awake()
16.     {
17.             Init();
18.     }
19.  
20.     public static void Init()
21.     {
22.         ResourceAmountDictionary = new Dictionary<ResourceType, int>();
23.         foreach (ResourceType resourceType in Enum.GetValues(typeof(ResourceType)))
24.         {
25.             ResourceAmountDictionary[resourceType] = 0;
26.         }
27.  
28.     }
29.  
30.     public static void AddResourceAmount(ResourceType resourceType, int amount)
31.     {
32.         ResourceAmountDictionary[resourceType] += amount;
33.        
34.         FindObjectOfType<WindowGameResources>().UpdateResourceTextObject();
35.     }
36.  
37.     public static int GetResourceAmount(ResourceType resourceType)
38.     {
39.         return ResourceAmountDictionary[resourceType];
40.     }

 

I'm not saying this is the best solution because well... it's not.

But FindObjectOfType also has a plural version FindObjectsOfType:
https://docs.unity3d.com/ScriptReference/Object.FindObjectsOfType.html

 

I am aware but it does not allow me to call the method if I use the plural .

 

The more appropriate approach would be to invert that dependency. Why does WindowGameResources need to know about GameResources AND GameResources know about WindowGameResources. This is called a "coupled dependency". One can't exist with out the other.

It'd be like if I was reading a book... my reading the book depends on the book existing. But it'd be really weird if the book existing depended on my reading it.

 

Loop the array that is returned?

 

If this was my game, WindowGameResources would be listening for C# events from GameResources and updating whenever the resource value it was interested in changed. I understand that might be a lot for a beginner though.

 

Oh wow, Lord, thank you very much. I am quite new to scripting, but this worked, as in the looping through the array. I didn't realise it was an array.

I am particularly interested in your other comment about the dependancy. Please, can you elaborate ? How to create such a structure ?

 

Hi Praetor, I actually had an event previously but it caused me problems when I tried to reload the scene and thought I would try to achieve it with methods. But yes, I agree, that with events this particular problem did not exist.

 

Events is one way like @PraetorBlue suggested. And honestly is the first thing I'd jump to in this situation if rapidly trying to get something set up.

Something like (note I personally wouldn't use singleton either, but this is the simplest thing to do here without getting to far off base from resolving your issue):

Code (csharp):

1.  
2. public class GameResources : MonoBehaviour
3. {
4.  
5.     public enum ResourceType
6.     {
7.         apple,
8.         orange,
9.         lemon,
10.     }
11.  
12.     //simple singleton
13.     private static GameResources _instance;
14.     public static GameResources Instance { get { return _instance; } }
15.  
16.     public event System.EventHandler ResourceAmountAdded;
17.  
18.     Dictionary<ResourceType, int> ResourceAmountDictionary;
19.  
20.  
21.     private void Awake()
22.     {
23.         //simple singleton initialization
24.         if(_instance != null)
25.         {
26.             Destroy(this);
27.             return;
28.         }
29.      
30.         _instance = this;
31.      
32.         //our proper init
33.         ResourceAmountDictionary = new Dictionary<ResourceType, int>();
34.         foreach (ResourceType resourceType in Enum.GetValues(typeof(ResourceType)))
35.         {
36.             ResourceAmountDictionary[resourceType] = 0;
37.         }
38.     }
39.  
40.     public void AddResourceAmount(ResourceType resourceType, int amount)
41.     {
42.         ResourceAmountDictionary[resourceType] += amount;
43.      
44.         ResourceAmountAdded?.Invoke(this, System.EventArgs.Empty);
45.     }
46.  
47.     public int GetResourceAmount(ResourceType resourceType)
48.     {
49.         return ResourceAmountDictionary[resourceType];
50.     }
51.  
52.     //...
53. }
54.  

Code (csharp):

1.  
2. public class WindowGameResources : MonoBehaviour
3. {
4.     [SerializeField]
5.     GameResources.ResourceType resourceType;
6.     [SerializeField]
7.     Text resourceText; //assign this through the editor or some other manner, don't use find in awake
8.  
9.     private void Start()
10.     {
11.         UpdateResourceTextObject();
12.      
13.         GameResources.Instance.ResourceAmountAdded += OnResourceAmountAdded;
14.     }
15.  
16.     private void OnDestroy()
17.     {
18.         GameResources.Instance.ResourceAmountAdded -= OnResourceAmountAdded;
19.     }
20.  
21.     private void OnResourceAmountAdded(object sender, System.EventArgs e)
22.     {
23.         UpdateResourceTextObject();
24.     }
25.  
26.     public void UpdateResourceTextObject()
27.     {
28.             resourceText.text =
29.                 GameResources.GetResourceAmount(resourceType).ToString();
30.     }
31. }
32.  

 

Lord, I don't want to say a big word but you might have hit two birds with one stone here. I was previously using an Event similar to what you have in your code except for the singleton bit and the OnDestroy method. On reloading the scene, it was giving me a weird message that it cannot find the text boxes to update the resource values. I suspect your additions will fix that. Well, many thanks, you have been very helpful. I banged my head for many hours over this (I know).

 

If you are really interrested, heres a full thread about code architecture in unity. ^^
https://forum.unity.com/threads/how-to-make-the-programming-architecture-of-my-game.916661/

 

Hi Lord,

I implemented your event solution today with a few tweaks as I was getting some compile issues. I experimented a bit with it. Firstly, I commented out the singleton bit and the game works fine. Secondly, I commented out the OnDestory() unsubscribe bit and the game gives me an error 'missing reference exception, object of type text has been destroyed.

So, I guess I just wanted your take on why you think the singleton bit was important as the game still works without it? Also, why is the event tied to a specific text object ? Shouldn't the event just trigger the appropriate method to update ANY text box that is referenced in the code ? Many thanks.

Code (CSharp):

1. public class WindowGameResources : MonoBehaviour
2. {
3.     [SerializeField] GameResources.ResourceType resourceType = default;
4.     [SerializeField] Text resourceText = default;
5.  
6.     private void Start()
7.     {
8.         GameResources.ResourceAmountAdded += OnResourceAmountAdded;
9.         UpdateResourceTextObject();
10.     }
11.  
12.     private void OnDestroy()
13.     {
14.        // GameResources.ResourceAmountAdded -= OnResourceAmountAdded;
15.     }
16.  
17.  
18.     private void OnResourceAmountAdded(object sender, System.EventArgs e)
19.     {
20.         UpdateResourceTextObject();
21.     }
22.  
23.     public void UpdateResourceTextObject()
24.     {
25.             resourceText.text =
26.                 GameResources.GetResourceAmount(resourceType).ToString();
27.     }
28. }

Code (CSharp):

1. public class GameResources : MonoBehaviour
2. {
3.  
4.     public enum ResourceType
5.     {
6.         tomato,
7.         orange,
8.         lemon,
9.     }
10.  
11.     // private static GameResources _instance;
12.     // public static GameResources Instance { get { return _instance; } }
13.  
14.     public static event System.EventHandler ResourceAmountAdded;
15.  
16.     static Dictionary<ResourceType, int> ResourceAmountDictionary;
17.  
18.  
19.     private void Awake()
20.     {
21.        /* if (_instance != null)
22.         {
23.             Destroy(this);
24.             return;
25.         }
26.  
27.         _instance = this;*/
28.    
29.         ResourceAmountDictionary = new Dictionary<ResourceType, int>();
30.         foreach (ResourceType resourceType in Enum.GetValues(typeof(ResourceType)))
31.         {
32.             ResourceAmountDictionary[resourceType] = 0;
33.         }
34.  
35.     }
36.  
37.     public static void AddResourceAmount(ResourceType resourceType, int amount)
38.     {
39.         ResourceAmountDictionary[resourceType] += amount;
40.         ResourceAmountAdded?.Invoke(null, EventArgs.Empty);
41.     }
42.  
43.     public static int GetResourceAmount(ResourceType resourceType)
44.     {
45.         return ResourceAmountDictionary[resourceType];
46.     }
47. }

 

Because static states are fragile design. It makes any refactoring difficult, there are some gotchas in terms of how the Unity editor behaves, and it's just good habit to avoid static state because in more complicated setting than this its fragility can get more rough.

This isn't to say Singleton is much better... and is why I said I wouldn't necessarily use a singleton either. But completely refactoring your code would have wildly changed everything to an extent that you wouldn't have recognized it. And well singleton is a common enough pattern here in the unity community that you will end up becoming famliar with it in due time anyways. And Singleton at least reintroduces the concept of "object identity" that static lacks.

It's not?

The event is part of GameResources. It allows GameResources to signal that something has changed.

Each of your WindowGameResources can then listen for that event. And it decides to update the textbox, that textbox being the one it has referenced.

Beyond that if there's some functionality/behaviour/intent I'm missing... that's just because I don't know what it is you're attempting to accomplish. Your code is so far out of context and has such generic names I honestly don't know what any of it is actually supposed to be doing in the grand scheme of things... I'm just applying general techniques to how you accomplish signaling that the state of one object has changed without creating a tightly coupled dependency.

Like I said before though, this isn't necessarily the only way to do it... nor is it the best way since I don't know what you exactly want to accomplish. But it's a straight forward and simple way and is inline with what PraetorBlue was talking about as well.

 

Thanks for your help. I am a beginner so some of this stuff is flying over my head.

Re: the second point, I have a timer and when the time is up the user gets prompted to 'retry' which reloads the scene using the scenemanager. I am guessing all objects get destroyed and recreated - at that stage I am getting an error (the object of type text has been destroyed) at

resourceText.text = GameResources.GetResourceAmount(resourceType).ToString();

Not an issue as your code below solves the problem, just got curious why it was happening since the event should be independent of the 'listeners':

GameResources.ResourceAmountAdded -= OnResourceAmountAdded;