Is there a way to automatically prevent redundant monobehaviours (a la colliders?)

Unity Engine
1

When you try to add a Collider to a GameObject that already has one, Unity won’t let you. Is there any way to put the same restrictions on a custom MonoBehaviour? Right now I’m doing some pretty hacky stuff in the MonoBehaviour’s Awake() to work around it in play mode, but it’d be nice if I could just stop it from ever happening, especially within edit mode. There really ought to be an attribute for it (maybe something for the wish list.)

2

well, i got my hack good enough that i’m happy with it, although it will only work if you can get away with using [ExecuteInEditMode]. here it is, if anyone wants it:

[ExecuteInEditMode]
public class MyMonoBehaviour : MonoBehaviour {

void Awake ()
	{
		MyMonoBehaviour[] localInstances = gameObject.GetComponents<MyMonoBehaviour>();
		
		if (localInstances.Count() > 1) {
				Debug.Log ("Can't add component 'MyMonoBehaviour' to " + this.gameObject.name + "because such a component is already added to the game object!");
			StartCoroutine(DestroyNextFrame());
			
		} 
		else 
		{
			//whatever you'd do otherwise
		}
	}
	
	IEnumerator DestroyNextFrame ()
	{
		yield return 1;
		DestroyImmediate (this);
	}

the use of a coroutine seems necessary to prevent this apparently harmless but annoying error that obscures the Debug message:

m_InstanceID == 0
UnityEditorInternal.InternalEditorUtility:InspectorWindowDrag(Object, Boolean)
UnityEditor.DockArea:OnGUI()