[Closed] Change Handler on array of objects

This may be simple but I haven’t found a way:

I have an array of objects el (Render Elements) and want to receive the index of the object where something has been changed.

when parameters el change id:#checked_changes o do (...)

Since the render elements aren’t necessarily identifiable with any of their properties I’m not able to find out the index.

I tried to use a 2D-array with an id for every element but “Change handler setup requires a collection of MAX objects, got: #(1, ReferenceTarget:VRayDiffuseFilter)”

Is there a better way than creating a handler for every element?