Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By : Alexey Soshin
Book Image

Kotlin Design Patterns and Best Practices - Second Edition

By: Alexey Soshin

Overview of this book

This book shows you how easy it can be to implement traditional design patterns in the modern multi-paradigm Kotlin programming language, and takes you through the new patterns and paradigms that have emerged. This second edition is updated to cover the changes introduced from Kotlin 1.2 up to 1.5 and focuses more on the idiomatic usage of coroutines, which have become a stable language feature. You'll begin by learning about the practical aspects of smarter coding in Kotlin, as well as understanding basic Kotlin syntax and the impact of design patterns on your code. The book also provides an in-depth explanation of the classical design patterns, such as Creational, Structural, and Behavioral families, before moving on to functional programming. You'll go through reactive and concurrent patterns, and finally, get to grips with coroutines and structured concurrency to write performant, extensible, and maintainable code. By the end of this Kotlin book, you'll have explored the latest trends in architecture and design patterns for microservices. You’ll also understand the tradeoffs when choosing between different architectures and make informed decisions.
Table of Contents (17 chapters)
1
Section 1: Classical Patterns
6
Section 2: Reactive and Concurrent Patterns
11
Section 3: Practical Application of Design Patterns

Decorator

In the previous chapter, we discussed the Prototype design pattern, which allows us to create instances of classes with slightly (or not so slightly) different data. This raises a question:

What if we want to create a set of classes that all have slightly different behavior?

Well, since functions in Kotlin are first-class citizens (which we will explain in this chapter), you could use the Prototype design pattern to achieve this aim. After all, creating a set of classes with slightly different behavior is what JavaScript does successfully. But the goal of this chapter is to discuss another approach to the same problem. After all, design patterns are all about approaches.

By implementing the Decorator design pattern, we allow the users of our code to specify the abilities they want to add.

Enhancing a class

Let's say that we have a rather simple class that registers all of the captains in the Star Trek universe along with their vessels:

open class StarTrekRepository...