Programming Ruby 3.3

Inheritance, Mixins, and Design

Inheritance and mixed-in modules both allow you to write code in one place and use that code in multiple classes. So, when do you use each?

As with most questions of design, the answer is, well…it depends. But over the years, developers have come up with some general guidelines to help us decide.

First, let’s look at subclassing. Classes in Ruby are related to the idea of types. It would be natural to say that "cat" is a string and [1, 2] is an array. And that’s another way of saying that the class of "cat" is String and the class of [1, 2] is Array. When we create our own classes, you can think of it as adding new types to the language. And when we subclass either a built-in class or our own class, we’re creating ...