Book Image

PHP Reactive Programming

By : Martin Sikora
Book Image

PHP Reactive Programming

By: Martin Sikora

Overview of this book

Reactive Programming helps us write code that is concise, clear, and readable. Combining the power of reactive programming and PHP, one of the most widely used languages, will enable you to create web applications more pragmatically. PHP Reactive Programming will teach you the benefits of reactive programming via real-world examples with a hands-on approach. You will create multiple projects showing RxPHP in action alone and in combination with other libraries. The book starts with a brief introduction to reactive programming, clearly explaining the importance of building reactive applications. You will use the RxPHP library, built a reddit CLI using it, and also re-implement the Symfony3 Event Dispatcher with RxPHP. You will learn how to test your RxPHP code by writing unit tests. Moving on to more interesting aspects, you will implement a web socket backend by developing a browser game. You will learn to implement quite complex reactive systems while avoiding pitfalls such as circular dependencies by moving the RxJS logic from the frontend to the backend. The book will then focus on writing extendable RxPHP code by developing a code testing tool and also cover Using RxPHP on both the server and client side of the application. With a concluding chapter on reactive programming practices in other languages, this book will serve as a complete guide for you to start writing reactive applications in PHP.
Table of Contents (18 chapters)
PHP Reactive Programming
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Subjects


We've been using Subjects in this book since Chapter 2, Reactive Programming with RxPHP, but there're multiple different variants of the Subject class for more specific use cases where all of them are relevant to multicasting.

BehaviorSubject

The BehaviorSubject class extends the default Subject class and lets us set a default value that is passed to its observer right on subscription. Consider this very simple example of BehaviorSubject:

// behaviorSubject_01.php  
use Rx\Subject\BehaviorSubject; 
 
$subject = new BehaviorSubject(42); 
$subject->subscribe(new DebugSubject()); 

When DebugSubject subscribes to the BehaviorSubject class, the default value 42 is emitted immediately. This is a similar functionality to using the startWith() operator.

The output is then just a single line:

$ php behaviorSubject_01.php
15:11:54 [] onNext: 42 (integer)

ReplaySubject

The ReplaySubject class internally contains an array of the last N values it received and automatically...