Hi, it's been a while since I wrote anything and posted. A lot is going on in the world, especially in the age of AI, when we have almost forgotten how to write simple code.

Continuing to the last post on observer design patterns. The quick recap about the previous post was about the publisher and subscriber. let's dive a little bit more and see what candidates we have to build an observer design pattern.

1. Observer (also known as subscriber)

2. Subject (also known as publisher)

3. Concrete Observer

4. Concrete Subject

5. Change Manager