custom Event invocation leaves me puzzled

I'm utterly puzzled as to why this does only print "Am I stupid" and not "Listener"
I hope this is minimal working example. No Errors or Exceptions. (on Unity 2019.1.2f1)

Code (CSharp):

1. public class TransformEvent : UnityEvent<Transform> {}
2. public class ElementAdding : MonoBehaviour
3. {
4.     public TransformEvent OnAdd => new TransformEvent();
5.     private void Start()
6.     {
7.         OnAdd.AddListener(_=>Debug.Log("Listener"));
8.         OnAdd.Invoke(transform);
9.         Debug.Log("Am I stupid?");
10. }}

Attaching a handler from another class and invoking from a button event yields the same result, so i do suspect, that it is not imporant to have a cycle between the addListener and the Invoke call.

 

I'm unfamiliar with what the => in a class level declaration does... but it compiles and fails in the way you indicate.

However if I change it to a simple class-level new assignment, it works as expected, as I would expect.

Code (csharp):

1. using UnityEngine;
2. using UnityEngine.Events;
3.  
4. public class TransformEvent : UnityEvent<Transform> {}
5. public class ElementAdding : MonoBehaviour
6. {
7.     public TransformEvent OnAdd = new TransformEvent();
8.     private void Start()
9.     {
10.         OnAdd.AddListener(_=>Debug.Log("Listener"));
11.         OnAdd.Invoke(transform);
12.         Debug.Log("Am I stupid?");
13.     }
14. }

 

You caught a typo i didn't realize was there... I am stupid apparently
=> on a field defines the following lambdy style expression as a getter, so each and every call to the OnAdd Field just gave me a new instance of the TransformEvent

Thank you very much i spent hours hunting this