UnityException: You are not allowed to call this function when declaring a variable

0
votes

I am trying to instantiate a GameObject and keep a reference to it but for some reason the above error appears every time it is instantiated even though the instantiation still goes through. The line of code it points me to is this: GameObject next = Instantiate(prefab); Like I said, the instantiation still works correctly, but in the interest of stability, I would like to get rid of this error. What does Unity want from me?

3
unity3druntime-error
Are you using c# or Javascript? – Rana
note too that you should not use 'next' as a variable name in c# – Fattie
WTF dude you need to TICK AN ANSWER! – Fattie
@JoeBlow Sorry, I'm nu here. Done. – RedstoneRusty

3 Answers

4
votes

You're all wrong. Roughly speaking, Instantiate returns

WHAT YOU PASS IN.

if you have this ...

   public GameObject modelDinosaur;

you can indeed have this

   GameObject nu = Instantiate(modelDinosaur);

No need to cast. (It's totally OK to cast if you want to.)

Yes, for a prefab, do exactly what everyone tells you above

  GameObject nu = (GameObject)Instantiate(yourPrefab);

BTW it is idiomatic to use "nu" (like "new") as the temporary variable. ("new" is a keyword of course, you can't use that.)

Most commonly you then do these things ..

   GameObject nu = Instantiate(modelDinosaur);
   YourDinoScript nuD = nu.GetComponent<YourDinoScript>();
   yourDinoList.Add(nuD);
   nu.name = "dynamic " + counter;
   nuT = nu.transform;
   nuT = blah blah
   nuT = your holder
   nuT = logic position
   etc etc

PS: regarding Unity's doco, you might as well read the ravings of a drunk chatbot. Forget it.

2
votes

The Unity Instantiate method has a return type of Object. You need to instantiate your prefab as a GameObject if you want to store it in a GameObject variable.

Assuming you are using C#, you can instantiate a GameObject and store it in a variable like so:

GameObject myGameObject = Instantiate(prefab) as GameObject;
2
votes

Instantiate() return an Object, You need to cast it to GameObject Explicitly.

Try this:

GameObject next = (GameObject)Instantiate(prefab);

More information:

Instantiate() signature: public static Object Instantiate(Object original)

This clearly shows that the return type is Object and not Gameobject

Reference

Please refer to this for more details