Hi Mark Collins-Cope. Thanks for your inputs. Appreciate it.

I think you miss my point in the article. The entire message is, SOLID Principles are good. But applying SOLID principles doesn’t mean we make the architecture solid and will no longer need to change all the underlying classes anymore. The simple reason is, we can never anticipate change.

Any software should never be solid. It is meant to change at some point. Even for principles like Open-Closed. No classes are supposed to be closed to changes forever. If that does happen, those codes will stale and no one will dare to touch them anymore. That would be scary.

My classes are made without states, just to simplify the illustration. I can always put states in it, but it doesn’t contribute to my point. Hence I made them as simple as possible.