[Feature] Making UnityAtoms compatible with Enter The PlayMode feature of Unity

Enter The PlayMode is a feature that makes entering the play mode insanely fast.

But there are side effects:

• Fields marked with [NonSerialized] attribute keep their values - as script serialization step is skipped completely and scripts remain the same, all data is carried to the Play Mode.
• Static variables keep their values - because Domain Reload does not happen types stay initialized.
• Static events keep their subscribers.
• There is no extra OnDisable/OnEnable calls for ExecuteInEditMode scripts.
• ScriptableObject, MonoBehaviour fields which are not serialized into the build ([NonSerialized], private or internal) keep their values - as existing objects are not recreated and constructors are not called.
• Watch out for null private and internal fields of array/List type - they are converted to an empty array/List object during Domain Reload and stay non null for game scripts.
• ExecuteInEditMode/ExecuteAlways scripts are not destroyed/awaken - no OnDestroy/Awake calls for those.
• Watch out for Awake/OnEnable methods which check EditorApplication.isPlaying property - Awake is not called and OnEnable is called only when EditorApplication.isPlaying is already true on Play Mode change.

UnityAtoms gets heavily impacted by these side effects. OnEnable and OnDisable calls are not called anymore. So nothing works as expected.

I exactly don’t know how we are supposed to change the code at the moment. So I created this issue for the discussion about it.

There are some useful callbacks that we can use.

• EditorApplication.playModeStateChanged event
• [RuntimeInitializeOnLoadMethod] attribute

What do you think?

[AdamRamberg]

Thanks a bunch both of you for the explanations 🙏

I agree, makes sense what you @rhys-vdw are suggesting.

[rhys-vdw]

Just to go into more detail on the RuntimeInitializeOnLoadMethodAttribute idea:

I think you could have a single static handler that calls Resources.FindObjectsOfTypeAll like:

[RuntimeInitializeOnLoadMethodAttribute]
static void ResetAll() {
  // get all atoms currently in memory.
  var atoms = Resources.FindObjectsOfTypeAll(typeof(IAtomBaseInterface)) as IAtomBaseInterface[];
  // reset current value to initial value.
  foreach (var a in atoms) a.Reset();
}

Might be more appropriate to use EditorApplication.playModeStateChanged (as @pnarimani suggested) since exiting playmode is also important.