Discussion: OO 101 Solutions and the Open Close Principle at the archi

This post is based on the transcript of a conversation between me and Luke Breuer, regarding the application of the Open Close Principle to the system architecture. The quoted sections are Luke's, and my own responses are shown underneath them. This is a different style from my usual posts, because this is a conversation, which was transcriptted and only slighted edited. I hope that this would help all those who wanted to know more about what I meant about using OPC at the architecture level and how to structure systems where you only ever add new things.