title: Trigger an event when something changes in a class
body: <p>Is it possible to trigger some event when something changes in a given class?</p>
  
  <p>E.g. I have a class that has <code>100</code> fields and one of them is being modified externally or internally. Now I want to catch this event. How to do this?</p>
  
  <p>The most I wonder if there is a trick to do this quickly for really extended classes.</p>