Access subclass variables not allowed?

Question

Hello, I have 2 scripts as follows:

 // Script_A.cs
 
 using UnityEngine;
 using System.Collections;
 
 public class Script_A : MonoBehaviour
 {
     public float number_One = 1;
 
     public class Script_A_Subclass : MonoBehaviour
     {
         public float number_Two = 2;
     }    
 }

 // Script_B.cs
 
 using UnityEngine;
 using System.Collections;
 
 public class Script_B : MonoBehaviour
 {
     public Script_A firstScript;
     public Script_A.Script_A_Subclass firstScriptSubclass;
 
     void Update ()
     {
         firstScript.number_One = 100001;
         firstScriptSubclass.number_Two = 22222;
     }
 }

The issue I'm having is I can access from Script_B.cs the variable number_One but not number_Two. Does Unity3D allow access to subclass variables like this? If so, how do you access them? I'm getting an error that "NullReferenceException: Object reference not set to an instance of an object Script_B.Update () (at Assets/Script_B.cs:14)".

Thanks again.

Answer 1

Best Answer

Answer by NorthernEagle · Apr 02, 2015 at 07:53 PM

Ok so I've been bashing my head here trying to figure this coding out. Thank you all for the help. I've added the following to Script_B.cs:

 void Start ()
     {
         // add components here
         firstScript = cube.AddComponent<Script_A> () as Script_A;
     }

That code loads the script perfectly onto my test cube gameObject but I can only access the parent class in Script_A.cs. All the Script_A.cs child class are untouchable and blind to Script_B.cs.

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Bonfire-Boy · Apr 02, 2015 at 08:33 PM 1

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What do you mean by "All the Script_A.cs child class are untouchable and blind to Script_B.cs."? The subclass is public in Script_A so why is it any less accessible to Script_B than the base class is?

NorthernEagle · Apr 02, 2015 at 10:25 PM 0

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Wish I knew why I can't access the children in Script_A from Script_B. I've got it to work well now with the following code: The addition of Static and direct calling from Script_B works now.

 // Script_A.cs
 
 using UnityEngine;
 using System.Collections;
 
 public class Script_A : $$anonymous$$onoBehaviour
 {
     public static float number_One = 1;
 
     public class Script_A_Subclass : $$anonymous$$onoBehaviour
     {
         public static float number_Two = 2;
     }    
 }
 
 // Script_B.cs
 
 using UnityEngine;
 using System.Collections;
 
 public class Script_B : $$anonymous$$onoBehaviour
 {
     public Script_A firstScript;
     public Script_A.Script_A_Subclass firstScriptSubClass;
     public GameObject cube;
 
     void Start ()
     {
         // add components here
         //firstScriptSubClass = cube.AddComponent<Script_A.Script_A_Subclass> () as Script_A.Script_A_Subclass;
     }
 
     void Update ()
     {
         Script_A.number_One = 11111111;
         Script_A.Script_A_Subclass.number_Two = 22222222;
 
         // print out values
         Debug.Log ("NumberOne: " + Script_A.number_One + "NumberTwo: " + Script_A.Script_A_Subclass.number_Two);
     }
 }

Answer 2

Answer by sumeeton · Apr 01, 2015 at 06:01 AM

You haven't initialized the variables, hence the NullReferenceException

 // Script_A.cs
  
  using UnityEngine;
  using System.Collections;
  
  public class Script_A : MonoBehaviour
  {
      public float number_One = 1;
  
      public class Script_A_Subclass : MonoBehaviour
      {
          public float number_Two = 2;
      }    
  }
  
  // Script_B.cs
  
  using UnityEngine;
  using System.Collections;
  
  public class Script_B : MonoBehaviour
  {
      public Script_A firstScript;
      public Script_A.Script_A_Subclass firstScriptSubclass;
  
      void Start ()
      {
           // Initialize here --------------------------------------
           firstScript = new Script_A();
           firstScriptSubclass = Script_A.Script_A_Subclass();
      }
      void Update ()
      {
          firstScript.number_One = 100001;
          firstScriptSubclass.number_Two = 22222;
      }
  }

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trololo · Apr 01, 2015 at 07:31 AM 1

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Yes but no, you should not instantiate a $$anonymous$$onoBehaviour class with the new keyword. Use AddComponent ins$$anonymous$$d or search for the script in the scene. Op: You can also use static variables in your case.

sumeeton · Apr 01, 2015 at 07:57 AM 0

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At the first place, what's the use of subclass extending monobehavior? From what I see, he is just using Script_A as struct.

Bonfire-Boy · Apr 02, 2015 at 08:35 PM 1

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I was assu$$anonymous$$g it's just a simple example of an idiom they're working with. But I'm also struggling to see the point, when the subclass is public. Would be interested to know if there is one, it's something I'd not considered before.

Access subclass variables not allowed?

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