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

Iterator

When we were discussing the Composite design pattern in the previous chapter, we noted that the design pattern felt a bit incomplete. Now is the time to reunite the twins separated at birth. Much like Arnold Schwarzenegger and Danny DeVito, they're very different but complement each other well.

As you may remember from the previous chapter, a squad consists of troopers or other squads. Let's create one now:

val platoon = Squad(
    Trooper(),
    Squad(
        Trooper(),
    ),
    Trooper(),
    Squad(
        Trooper(),
        Trooper(),
    ),
    Trooper()
)

Here, we created a platoon that consists of four troopers in total.

It would be useful if we could print all the troopers in this platoon...