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 value object design pattern


In programming, there are different ways of comparing data. We can compare object identities or their values. These are useful in different scenarios and here we will see what value objects are and when they can be used. Value objects are:

Note

Small and simple immutable objects. Their equality is based not on identity, but on value equality.

Value objects are used to represent numbers, money, dates, and so on. They should be small and immutable; otherwise, changing values could cause bugs and unexpected behavior. They are quite useful in multithreaded applications due to their immutability. They are also commonly used as data transfer objects in enterprise applications.

Class diagram

In languages such as Java, there is no direct support for value objects. What developers end up doing is declare the fields as final and implement the hashCode and equals methods.

Immutability, however, is a concept that is pretty much enforced in Scala. We already saw the algebraic...