is there any possible way to extend from the GameObject class

Question

im trying to use a more object oriented approach to a game im making, i noticed that if i do AddComponent and add a script to an object in my game, the update function on that object doesnt get called for some reason. Long story short i realized it would be much easier to accomplish what im going for if i could just derrive from the GameObject class. when i tried that i got an error that it cannot derrive from sealed type UnityEngine.GameObject. I know unity isnt too object oriented friendly, but is there any way to do this or do i have to refer to the gameObject component on my object to accomplish this?

 using UnityEngine;
 using System.Collections;
 
 public class Enemy : MonoBehaviour {
     /**
 
      * Class members
      **/
 
     int health;
     float speed; // meters per second
     GameObject obj;
     Vector3 location;
     string name;
 
 
     //the word function and method mean the same thing
 
     public Enemy(string name, GameObject myObj, Vector3 location)
     {
         this.name = name;
         obj = myObj;
         this.location = location;
         speed = 3;
         health = 10;
 
     }
     public Vector3 getLocation()
     {
         return location;
 
     }
 
     public GameObject getObject()
     {
         return obj;
     }
 
   
 
     public void setSpeed(float speed) //mutators & setters
     {
         speed ++;
     }
 
     public float getSpeed()
     {
         return speed;
     }
 
     public string getName()
     {
         return name;
     }
     
 }


 using UnityEngine;
 using System.Collections;
 
 public class Spawnner : MonoBehaviour { // spawner is extending from the Monobehaviour class (british people need to learn how to spell)
 
 
     Enemy Bob, Gene, Tina;
 
     // Use this for initialization
     void Start () {
 
         Bob = new Enemy("Bob", Resources.Load("mySphere") as GameObject, new Vector3(1, 0, 0));
         Gene = new Enemy("Gene", Resources.Load("mySphere") as GameObject, new Vector3(2, 0, 0));
         Tina = new Enemy("Tina", Resources.Load("mySphere") as GameObject, new Vector3(3, 0, 0));
 
         Instantiate(Bob.getObject(), Bob.getLocation(), transform.rotation);
         Instantiate(Gene.getObject(), Gene.getLocation(), transform.rotation);
         Instantiate(Tina.getObject(), Tina.getLocation(), transform.rotation);
 
         Bob.getObject().AddComponent<EnemyMovement>();
     }
     /**
     public void moveForward(Enemy myEnemy)
     {
         myEnemy.getObject().transform.position = new Vector3(myEnemy.getObject().transform.position.x, myEnemy.getObject().transform.position.y, myEnemy.getObject().transform.position.z + 1);
     }
     // Update is called once per frame
     void Update () {
       
         
     }
      * **/
 }



 using UnityEngine;
 using System.Collections;
 
 public class EnemyMovement : MonoBehaviour{
 
     float speed;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
         moveForward();
     }
 
     public void moveForward()
     {
         transform.position = new Vector3(transform.position.x, transform.position.y, transform.position.z + 1);
        
     }
 }

When i press play, i can see the script gets added to the prefab, but it doesnt move. If i press play again, it adds a second script to it and they all start moving(because they all have the same prefab). Im well aware there are much easier ways to move a gameobject in unity, but i really want to know why the script doesnt get used if i use AddComponent, and also from research i found out there is no way to extend the GameObject class.

Answer 1

Answer by D3Duck · Sep 30, 2015 at 07:37 PM

To use AddComponent, it needs to be a MonoBehavior. Which it is so it should work. A GameObject can not be extended as far as I know. You are adding a script to the GameObject in the world and this is how Unity is designed to work.

So Tanoshimi is using the correct code:

 GameObject newBob = Instantiate(Bob.getObject(), Bob.getLocation(), transform.rotation) as GameObject;
 newBob.AddComponent<EnemyMovement>();

For example: when you right click in the hierarchy and select "Create Empty", you made a new GameObject.

Then when you click the new GameObject and then in the inspector click Add Component and then add your Enemy script, you have done what you would do with AddComponent().

Again, You are not supposed to "Add" to the GameObject. You are supposed to add a component to the list of components OF that GameObject with AddComponent();

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Answer 2

Answer by tanoshimi · Sep 30, 2015 at 06:29 PM

You need to add the component to the instance you just created, (i.e. what's returned by Instantiate()) not to the gameobject you cloned (i.e. the parameter you supplied to Instantiate()).

Try this pattern around line 75:

 GameObject newBob = Instantiate(Bob.getObject(), Bob.getLocation(), transform.rotation) as GameObject;
 newBob.AddComponent<EnemyMovement>();

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D3Duck · Sep 30, 2015 at 07:02 PM 0

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This is the correct solution. You are not adding your component to what you make but are adding it to something else, so of course Update() never gets called.

It doesn't get more object oriented than this =p

Vice_Versa · Sep 30, 2015 at 07:18 PM 0

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I see what you guys are saying, however i made a custom class called Enemy, which is not of type GameObject so AddComponent wont work. Hence my original question of can the GameObject class be extended

tanoshimi Vice_Versa · Sep 30, 2015 at 07:39 PM 0

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No it can't - it's sealed (but you already knew that because you stated it in your question). The correct solution is to add a component.

is there any possible way to extend from the GameObject class

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