Book Image

PHP 8 Programming Tips, Tricks and Best Practices

By : Doug Bierer
Book Image

PHP 8 Programming Tips, Tricks and Best Practices

By: Doug Bierer

Overview of this book

Thanks to its ease of use, PHP is a highly popular programming language used on over 78% of all web servers connected to the Internet. PHP 8 Programming Tips, Tricks, and Best Practices will help you to get up-to-speed with PHP 8 quickly. The book is intended for any PHP developer who wants to become familiar with the cool new features available in PHP 8, and covers areas where developers might experience backward compatibility issues with their existing code after a PHP 8 update. The book thoroughly explores best practices, and highlights ways in which PHP 8 enforces these practices in a much more rigorous fashion than its earlier versions. You'll start by exploring new PHP 8 features in the area of object-oriented programming (OOP), followed by enhancements at the procedural level. You'll then learn about potential backward compatible breaks and discover best practices for improving performance. The last chapter of the book gives you insights into PHP async, a revolutionary new way of programming, by providing detailed coverage and examples of asynchronous programming using the Swoole extension and Fibers. By the end of this PHP book, you'll not only have mastered the new features, but you'll also know exactly what to watch out for when migrating older PHP applications to PHP 8.
Table of Contents (17 chapters)
Section 1: PHP 8 Tips
Section 2: PHP 8 Tricks
Section 3: PHP 8 Best Practices

Understanding PHP 8 expanded variance support

The concept of variance is at the heart of OOP. Variance is an umbrella term that covers how the various subtypes interrelate. Some 20 years ago, a pair of early computer scientists, Wing and Liskov, devised an important theorem that is at the heart of OOP subtypes, now known as the Liskov Substitution Principle.

Without going into the precise mathematics, this principle can be paraphrased as follows:

Class X can be considered a subtype of class Y if you are able to substitute an instance of X in place of an instance of Y, and the application's behavior does not change in any way.


The actual paper that first described and provided the precise mathematical formulaic definition of the Liskov Substitution Principle can be found here: A behavioral notion of subtyping, ACM Transactions on Programming Languages and Systems, by B. Liskov and J. Wing, November 1994 (

In this...