Poor/Wrong documentation of SMB instantiation

I use a simple StateMachineBehaviour to be able to subscribe to Entering events and exiting events. I noticed that subsribing to the SMB in necessary to be done at every OnEnable, because the SMB seems to be discarded and recreated at every OnDisable/OnEnable. In the documentation it is said to be best practice to get the component on Start (Which I would rather much prefer, way more elegant), but this is just not the case with the current implementation of SMBs.

Here are the scripts:

Spoiler: StateMachineEvents

Code (CSharp):

1. // --------------------------------------------------------------------------------------------------------------------
2. // <copyright file="StateMachineEvents.cs" company="Supyrb">
3. //   Copyright (c) 2017 Supyrb. All rights reserved.
4. // </copyright>
5. // <author>
6. //   Johannes Deml
7. //   send@johannesdeml.com
8. // </author>
9. // --------------------------------------------------------------------------------------------------------------------
10.  
11. using System.Collections;
12. using System.Collections.Generic;
13. using UnityEngine;
14.  
15. namespace Supyrb
16. {
17.     public class StateMachineEvents : StateMachineBehaviour
18.     {
19.         public delegate void StateMachineDelegate(Animator animator, AnimatorStateInfo stateInfo, int layerIndex);
20.  
21.         public event StateMachineDelegate OnAnimationStateEnter;
22.         public event StateMachineDelegate OnAnimationStateExit;
23.  
24.         // OnStateEnter is called before OnStateEnter is called on any state inside this state machine
25.         public override void OnStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
26.         {
27.             Debug.Log("State entered");
28.             if (OnAnimationStateEnter != null)
29.             {
30.                 OnAnimationStateEnter(animator, stateInfo, layerIndex);
31.             }
32.         }
33.  
34.         // OnStateExit is called before OnStateExit is called on any state inside this state machine
35.         public override void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
36.         {
37.             Debug.Log("State exited");
38.             if (OnAnimationStateExit != null)
39.             {
40.                 OnAnimationStateExit(animator, stateInfo, layerIndex);
41.             }
42.         }
43.     }
44. }
45.  

Spoiler: StateMachineSubscriber

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using Supyrb;
4. using UnityEngine;
5.  
6. [RequireComponent(typeof(Animator))]
7. public class StateMachineSubscriber : MonoBehaviour
8. {
9.     private Animator anim;
10.     private StateMachineEvents stateMachineEvents;
11.  
12.     void Awake()
13.     {
14.         anim = GetComponent<Animator>();
15.     }
16.  
17.     /// <summary>
18.     /// The SMB that is subscribed to gets lost after gameobject is disabled
19.     /// It would be necessary to subscribe at every OnEnable to the new SMB instance
20.     /// </summary>
21.     void Start()
22.     {
23.         stateMachineEvents = anim.GetBehaviour<StateMachineEvents>();
24.         stateMachineEvents.OnAnimationStateEnter += OnStateEnter;
25.     }
26.  
27.     private void OnStateEnter(Animator animator, AnimatorStateInfo stateinfo, int layerindex)
28.     {
29.         Debug.Log("State enter received!");
30.     }
31. }

And here is a gif of the outcome. Notice that the event is only received once (because the SMB changes at every deactivation).


The documentation in question is this one: https://unity3d.com/learn/tutorials/modules/beginner/5-pre-order-beta/state-machine-behaviours

I do understand why the current implementation is like that, but I think it is rather inconsistent. With ScriptableObjects you would not expect that behavior, and with MonoBehaviours you would for sure not expect that behavior.

@Mecanim-Dev : Are there any plans to sync the behavior to the (at least from my standpoint) more intuitive one?

Hope this helps others avoid strange bugs