Let’s examine a refactoring to move code to follow the open/closed principle. We’ll see how the resulting calling code becomes much easier to read locally, without having to open other files or classes to understand what’s going on. Open/closed principle First, let’s do a quick recap of the open/closed principle. Classes should be open to extension, but closed to modification. What does that mean? Let’s take it a half at a time.

Ruby Reactoring