Programming Scala, 3rd Edition

Chapter 9. Object-Oriented Programming in Scala

One reason Scala is a superb OOP language is because Martin Odersky and his collaborators have thought long and hard about how to make OOP best practices as concise as possible. While we already know many of Scala’s features for OOP, now we will explore them more systematically. We’ll see more examples of Scala’s concise syntax and how it enables effective OOP in combination with FP.

I’ve waited until now to explore Scala as an OOP language for two reasons.

First, I wanted to emphasize that FP has become an essential skill set for modern problems, a skill set that may be new to you. When you start with Scala, it’s easy to use it as a better OOP language, a “better Java,” and neglect the power of its FP side.

Second, a common architectural approach with Scala has been to use FP for programming in the small and OOP for programming in the large. Using FP for implementing algorithms, manipulating data, and managing state in a principled way is our best way to minimize bugs, the amount of code we write, and the risk of schedule delays. On the other hand, Scala’s OOP model provides tools for designing composable, reusable, and encapsulated modules, which are essential for building larger applications. Hence, Scala gives us the best of both worlds.

I’ve assumed you already know the basics of OOP from other languages, so many concepts were defined quickly and informally throughout the book. This chapter starts with a quick review of class ...