Mr Ivan:

The issue as to whether you should store a rule class in its own library and drop an instance in a CDE is really about a single factor ... are you likely to re-use that rule anywhere else? If the answer is "yes", then store it in its own library. If not, don't. Remember that if you create a rule in a CDE and then decide you want to make it into a "superclass", you can always save it as a class in its own library and then simply drop an instance of it back to the originating CDE. I have done this a few times where I started out a rule class in the CDE and thought, hmmm, I could use that again. In these circumstances I have simply extracted it from the CDE into its own library.

As to the new method, ask yourself to what part of your application is it specific? If it is a method to enhance rule classes generally, you could create an IvanRuleClass, add the method there and base all other rules on your IvanRuleClass, thereby adding the new method to each and every rule instance. If the method is domain specific and part of your application's business logic and perhaps, more importantly, specific to the cursors in a single CDE, then it is likely better added to the CDE in question or added to a utility class library that can be called from wherever it is required whether that be in a method or event of a rule class or CDE.

HTH