Book Image

Hands-On Design Patterns with Kotlin

By : Alexey Soshin
Book Image

Hands-On Design Patterns with Kotlin

By: Alexey Soshin

Overview of this book

Design patterns enable you as a developer to speed up the development process by providing you with proven development paradigms. Reusing design patterns helps prevent complex issues that can cause major problems, improves your code base, promotes code reuse, and makes an architecture more robust. The mission of this book is to ease the adoption of design patterns in Kotlin and provide good practices for programmers. The book begins by showing you the practical aspects of smarter coding in Kotlin, explaining the basic Kotlin syntax and the impact of design patterns. From there, the book provides an in-depth explanation of the classical design patterns of creational, structural, and behavioral families, before heading into functional programming. It then takes you through reactive and concurrent patterns, teaching you about using streams, threads, and coroutines to write better code along the way By the end of the book, you will be able to efficiently address common problems faced while developing applications and be comfortable working on scalable and maintainable projects of any size.
Table of Contents (13 chapters)

The fan-out design pattern

What if the amount of work at different steps in our pipeline is very different?

For example, it takes a lot more time to fetch the HTML than to parse it. Or what if we don't have a pipeline at all, just a lot of tasks we would like to distribute between coroutines.

That's where the fan-out design pattern kicks in. The number of coroutines may read from the same channel, distributing the work.

We can have one coroutine produce some results:

private fun producePages() = produce {
for (i in 1..10_000) {
for (c in 'a'..'z') {
send(i to "page$c")
}
}
}

And have a function that would create a coroutine that reads those results:



private fun consumePages(channel: ReceiveChannel<Pair<Int, String>>) = async {
for (p in channel) {
println(p)
}
}

This allows us to generate...