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

Singleton

Singleton – the most popular bachelor in town. Everybody knows him, everybody talks about him, and everybody knows where to look for him.

Even people who don't like using design patterns will know Singleton by name. At one point, it was even proclaimed an anti-pattern, but only because of its wide popularity.

So, for those who are encountering it for the first time, what is this design pattern all about?

Usually, if you have a class, you can create as many instances of it as you want. For example, let's say that we both are asked to list all of our favorite movies:

val myFavoriteMovies = listOf("Black Hawk Down", "Blade   Runner")
val yourFavoriteMovies = listOf(...)

Note that we can create as many instances of List as we want, and there's no problem with that. Most classes can have multiple instances.

Next, what if we both want to list the best movies in the Quick and Angry series?

val myFavoriteQuickAndAngryMovies...