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

Functions as values

We already covered some of the functional capabilities of Kotlin in the chapters dedicated to design patterns. The Strategy and Command design patterns are only two examples that rely heavily on the ability to accept functions as arguments, return functions, store functions as values, or put functions inside of collections. In this section, we'll cover some other aspects of functional programming in Kotlin, such as function purity and currying.

Learning about higher-order functions

As we discussed previously, in Kotlin, it's possible for a function to return another function. Let's look at the following simple function to understand this syntax in depth:

fun generateMultiply(): (Int) -> Int {
    return fun(x: Int): Int {
        return x * 2
    }
}

Here, our generateMultiply function returns another function that doesn't have a name. Functions without...