Book Image

Scala Design Patterns

By : Ivan Nikolov
Book Image

Scala Design Patterns

By: Ivan Nikolov

Overview of this book

Scala has become increasingly popular in many different IT sectors. The language is exceptionally feature-rich which helps developers write less code and get faster results. Design patterns make developer’s lives easier by helping them write great software that is easy to maintain, runs efficiently and is valuable to the company or people concerned. You will learn about the various features of Scala and be able to apply well-known, industry-proven design patterns in your work. The book starts off by focusing on some of the most interesting features of Scala while using practical real-world examples. We will also cover the popular "Gang of Four" design patterns and show you how to incorporate functional patterns effectively. By the end of this book, you will have enough knowledge and understanding to quickly assess problems and come up with elegant solutions.
Table of Contents (20 chapters)
Scala Design Patterns
Credits
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface
Index

The lens design pattern


We already mentioned before that, in Scala, objects are immutable. You can, of course, make sure that a specific class has its fields declared as vars but this is discouraged and considered bad practice. After all, immutability is good and we should try to aim for it.

The lens design pattern was created specifically for that purpose and allows us to overcome the immutability limitation and at the same time preserve the code readability. In the following subsections, we will start with some code that doesn't use the lens design pattern and we will go step by step to show how to use it and how it improves our applications.

Lens example

In order to show the lens design pattern in practice, we will create a class hierarchy that is usually seen in enterprise applications. Let's imagine that we are building a system for a library that can be used by the employees of different companies. We might end up with the following classes:

case class Country(name: String, code: String...