Programming Scala, 2nd Edition

Chapter 8. Object-Oriented Programming in Scala

Scala is a functional programming language, but it is also an object-oriented programming language like Java, Python, Ruby, Smalltalk, and others. I’ve waited until now to explore Scala’s “OO side” for two reasons.

First, I wanted to emphasize that functional programming 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 Java,” a better object-oriented language, and neglect the power of its functional side.

Second, a common architectural approach that Scala promotes is 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 OO model provides tools for designing composable, reusable modules, which are essential for larger applications. Hence, Scala gives us the best of both worlds.

I’ve assumed you already understand the basics of object-oriented programming, such as Java’s implementation. If you need a refresher, see Robert C. Martin’s Agile Software Development: Principles, Patterns, and Practices or Bertrand Meyer’s comprehensive introduction, Object-Oriented Software Construction (both by Prentice Hall). If you aren’t familiar with design patterns, see Design Patterns: Elements of Reusable Object-Oriented ...