Having OnEnable() defined changes execution order?!?

Questions & Answers
1

EDIT: After doing some more research I came across this discussion, which explains what I described below…what a mess!
http://answers.unity3d.com/questions/217941/OnEnable-Awake-Start-order.html

Soooo I found out something interesting last night while trying to figure out why my LoadLevelAdditive() level’s gameObjects where calling their Awake() and Start() functions after everything in my current scene.

My class was as follow:

using UnityEngine;
using System.Collections;

public class ControlsManager : MonoBehaviour {
	
	// Singleton access
	private static ControlsManager _instance;
	public static ControlsManager Instance
	{
		get{ return _instance; }
	}
	
	public string[] controlPresetScenes;
	public GameObject[] controlPresets;
	
	
	#region Properties
	public GameObject ControlPreset01
	{
		get{ return controlPresets[0]; }
	}
	
	private GUI_Controls _guiControls;
	public GUI_Controls GUIControls
	{
		get
		{
			if( !_guiControls )
				_guiControls = GameObject.FindWithTag("Controls").GetComponent<GUI_Controls>();
			
			return _guiControls; 
		}
	}
	#endregion
	
	
    void Awake( )
	{
		if( !this.enabled ) return;
		
		_instance = this;
		
		Application.LoadLevelAdditive( controlPresetScenes[0] );
		Debug.LogWarning("Loading HUD controls in " + this);  // Gets called right away
	}
    void Start ( ) 
	{
		_guiControls = GameObject.FindWithTag("Controls").GetComponent<GUI_Controls>();
		Debug.LogWarning("Storing HUD controls.", transform);  // Gets call after FixedUpdate()/Update() from current scene's gameObjects
    }
	
}

Whit the code above, the Debug text “Loading HUD controls…” in Awake() gets called right away, but the line in Start() to GetComponent<>() always returns null, and the Debug text “Storing HUD controls…” is getting called AFTER FixedUpdate() and Update() functions for objects in the current scene…couldn’t figure out why.

Then while trying ANYTHING i could think of, I added OnEnable() to the class:

using UnityEngine;
using System.Collections;

public class ControlsManager : MonoBehaviour {
	
	// Singleton access
	private static ControlsManager _instance;
	public static ControlsManager Instance
	{
		get{ return _instance; }
	}
	
	public string[] controlPresetScenes;
	public GameObject[] controlPresets;
	
	
	#region Properties
	public GameObject ControlPreset01
	{
		get{ return controlPresets[0]; }
	}
	
	private GUI_Controls _guiControls;
	public GUI_Controls GUIControls
	{
		get
		{
			if( !_guiControls )
				_guiControls = GameObject.FindWithTag("Controls").GetComponent<GUI_Controls>();
			
			return _guiControls; 
		}
	}
	#endregion
	
	
	// KEEP HERE OR GUI_CONTROLS WON'T EXECUTE RIGHT AWAY ???
	void OnEnable()
	{
		// For some reason having OnEnable() defined makes the execution order of the loaded scene objects a priority
	}
	
	
    void Awake( )
	{
		if( !this.enabled ) return;
		
		_instance = this;
		
		Application.LoadLevelAdditive( controlPresetScenes[0] );
		Debug.LogWarning("Loading HUD controls in " + this);  // Still gets called right away
	}
    void Start ( ) 
	{
		_guiControls = GameObject.FindWithTag("Controls").GetComponent<GUI_Controls>();
		Debug.LogWarning("Storing HUD controls.", transform);  // Now gets called right after Awake() above !?!
    }
	
}

…and BOOM! Like magic, the call to GetComponent<>() in Start() is now returning my GUI_Controls class, AND the Debug text “Storing HUD controls…” is now appearing before FixedUpdate() and Update() functions, right after the Debug text “Loading HUD controls…” in Awake() (which still gets called at the same time).

Is this normal? I was taken by surprise, for sure! If anyone can “enlighten” me I would really appreciate it lol…

Thanks for your time guys!

Stephane

2

See this question

The answer from @Noisecrime says:

From the sound of it, this is the ‘OnEnable’ bug with script execution order. That is I suspect your ‘framework’ script does not have an OnEnable method in it, in which case for some odd reason it will get trumped in execution order by the scripts that do, despite any ordering you add to the script execution.

To fix this issue, simply add an OnEnable method to your framework script.

We also faced this issue today and it’s looking like a total mess in Unity3D code…