Eloquent Ruby

Chapter 14. Use Class Instance Variables

In the last chapter we saw how you can add methods to your classes, methods that concern themselves with the issues that affect a class as a whole. But wherever you have code, you’re going to want to have data, which raises the question of where to store your class-level data. In this chapter we will look at the two alternatives that Ruby gives us for storing class-level data, the class variable, and the class instance variable.

We are going to start by looking at class variables, those Ruby things that start with @@ and seem to be the easy answer to storing your class-related information. Sadly, we will discover that class variables behave in some unfortunate ways, making them less of a solution and ...