I think this is pretty close to "the right way" (as I see it). However, I want to add one thing: > With that method, you end up with something that is clean,

I think this is pretty close to "the right way" (as I see it). However, I want to add one thing: > With that method, you end up with something that is clean, and more importantly does exactly what is needed an no more. There is no bits 'that could be useful later' and are never implemented, or used, or tested, and the model fits the job. You want a clean abstraction that gets the job done, and cleanness is better than strict minimality. If you leave big gaps in your abstraction, then it's not a good abstraction anymore, and you'll probably have problems down the road (especially once things get transferred to a support group). It's definitely a judgement call how far you should take this, however. Generally, I want to do what I can to avoid tempting future developers to put new features at the wrong level of abstraction.