[Pharo-users] subscribe on system change

I want to do some logic when there is a change on the system, like when a new class is loaded or when a method change. I don't want to put this logic explicit on the methods of the system who do that. I would like to know if i could subscribe to those special events (method change, new method, changes on a class and so on) so I can do what I want outside those methods. I heard about the Announcements but I don't know if Announcements could help with this problem. Can anyone give me some highlights to do those things? Thanks! (I'm really trying with my english, hope it's understandable) -- Miguel Enrique Campusano Araya Estudiante de Ingeniería Civil en Computación Universidad de Chile