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 state design pattern


The state design pattern is really similar to the strategy design pattern we looked at in the previous chapter. Its purpose is to:

Note

Allow us to choose a different behavior of an object based on the object's internal state.

Basically, the difference between the state design pattern and the strategy design pattern comes from the following two points:

  • The strategy design pattern is about how an action is performed. It is usually an algorithm that produces the same results as other algorithms.

  • The state design pattern is about what action is performed. Depending on the state, an object could be doing different things.

Implementing the state design pattern also closely resembles the implementation of the strategy design pattern.

Class diagram

Imagine a media player. Most media players have a play button—when we activate it, it usually changes its appearance and becomes a pause button. Clicking the pause button now also does something different—it pauses the playback and reverts...