Mastering PHP Design Patterns

Table of Contents

Mastering PHP Design Patterns

Credits

About the Author

About the Reviewer

www.PacktPub.com

Why subscribe?

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Why Good PHP Developer Isnt an Oxymoron

Coding style - the PSR standards

Revising object-oriented programming

Polymorphism

Traits (multiple inheritance)

Scalar type hints

Limiting debug access to private/protected properties

Setting up the environment with Composer

The Gang of Four (GoF)

Creational design patterns

Dependency injection

Structural design patterns

Behavioral design patterns

Architectural patterns

Summary

2. Anti-Patterns

Why anti-patterns matter

Not invented here syndrome

Third-party dependencies with Composer

God objects

Environment variables in PHP source

Singletons (and why you should be using dependency injection)

Dependency injection

Database as IPC

Auto-increment database IDs

Cronjob imitating service

Software in place of architecture

Interface Bloat

Cart before the horse

Separation of development and operations

Excessive separation of development responsibilities

Error suppression operator

Blind faith

Sequential coupling

The big rewrite

Automated tests

Service splitting

Perfectly staged migrations

Tester-Driven Development

Bloated optimization

Analysis paralysis

Bikeshedding

Premature optimization

Uneducated manager syndrome

Wrong rocky foundations

Long methods

Magic numbers

Summary

3. Creational Design Patterns

Software design process

Simple Factory

Factory Method

Abstract Factory pattern

Lazy initialization

Builder pattern

Prototype pattern

Summary

4. Structural Design Patterns

Agile software architecture

Decorator

Adapter

Class Adapter

Object Adapter

FlyWeight

Composite

Bridge

Proxy pattern

Facade

Summary

5. Behavioral Design Patterns

Personality traits for passionate programmers

Observer pattern (SplObserver/SplSubject)

Iterators

IteratorAggregate

Iterator

The many iterators of PHP

Generators

Template Method design pattern

Chain of Responsibility

Strategy design pattern

Specification design pattern

Scheduled Task pattern

Summary

6. Architectural Patterns

Model-View-Controller (MVC)

Service-oriented architecture

Microservices

Asynchronous queueing

Message Queue pattern (Getting started with RabbitMQ)

Publish-Subscriber pattern

Summary

7. Refactoring

What is refactoring?

Test, test, and test again

Code smells

Long methods and duplicated code

Large class

Replacing complex logical statements and switch statements with polymorphism or the Strategy Pattern

Duplicating code following a single control structure

Long Parameter List and primitive obsession

Indecent exposure

Feature envy

Inappropriate intimacy

Deeply nested statements

Remove assignments to parameters

Comments

Encapsulating Composite with Builder

Replacing hard-coded notifications with Observer

Replacing one/many distinctions with Composite

Separate versions with Adapters

What do I tell my manager?

Summary

8. How to Write Better Code

Nature of a HTTP request

RESTful API design

Stateless nature

Versioning

Filtering

Sorting

Searching

Limiting fields

Returning new fields

When in doubt – KISS

Software development life cycle

On Scrum, and real Agility

You need to sack people sometimes

Lean project management

YAGNI and defering decisions

Monitoring

Tests fight legacy

Behavior-Driven Development

Summary

Mastering PHP Design Patterns

Mastering PHP Design Patterns

Copyright © 2016 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

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Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: September 2016

Production reference: 1230916

Published by Packt Publishing Ltd.

Livery Place

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Birmingham B3 2PB, UK.

ISBN 978-1-78588-713-0

www.packtpub.com

Credits

About the Author

Junade Ali was a technical lead at some of the UK's leading digital agencies and has also worked using PHP in mission-critical road-safety systems. He loves pushing PHP to its innovative limits. Having started his career as a web development apprentice, he still remains engaged in the academic computer science community.

Junade, an avid contributor to the PHP community, has also spoken at PHPTek and the Lead Developer Conference. In addition to this, Junade was interviewed by Cal Evans for Voices of the ElePHPant, and he has appeared on the PHP Roundtable. In this spirit, Junade is proud of his local PHP user group: PHPWarks. Currently, Junade works at CloudFlare as a polymath, and helps make the Internet more secure and faster.

Outside of development, Junade has an interest in law and political campaigns and is a published author on constitutional law.

About the Reviewer

Sworup Shakya has worked as a web developer for more than ten years. He started his career as a Flash ActionScript developer, before moving on to ASP.NET MVC, and finally to PHP. During his time as a developer, Sworup worked extensively with frameworks, be it ASP.NET MVC or AngularJS or Laravel. However, while he was working as an ActionScript developer, he had to create one, which gave him knowledge of design patterns and OOP concepts that has helped him improve in order to be able to work on the frameworks he had to work on later.

Sworup received his Bachelor of Information Technology degree from Purbanchal University in Nepal. He currently works with Zimris Technologies Nepal Pvt. Ltd., a subsidiary of Zimris, LLC, as a senior developer.

Sworup likes to keep on top of the current technologies, keeping an eye on StackOverflow, Laracasts forums, and occasional podcasts. He posts on these mediums whenever he can and is looking to start a technical blog documenting his experiences at http://sworup.com.np/. You can reach him at [email protected].

I would like to thank Suzanne Coutinho, Francina Pinto and Chaitanya Nair of Packt Publishing for giving me this opportunity and helping me through the review process. I would like to thank my friends, family and colleagues for their unconditional support.

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Preface

Have you ever been to a PHP conference? If not, I’d highly recommend it, it is the closest you can get to a living and breathing PHP community. A few weeks ago, I flew from London to St. Louis, Misouri, to speak at php[tek] (the PHP conference run by php[architect]). After the conference, there was a small tradition within the PHP community known as WurstCon. Essentially, hundreds of PHP conference attendees cram themselves into a small hot dog shop and host a hot dog convention, often to the complete surprise of the staff there. Likewise, community nights at PHP events are the warmest and most accepting community occasions you’ll ever run into; the PHP community is surely one that other development language communities envy.

As of PHP 7, the PHP project has changed dramatically; but what I love, remains strong. The warmth you will feel at any PHP conference, the openness in the documentation, and adoption in the language. Yes, there are practices that are undoubtedly bad within PHP itself; however, think of what the PHP community has recently achieved, ranging from PHPUnit to Composer. Throughout this book, bear in mind the improvements in PHP 7, a few of which I’ll share with you. The trajectory of the project is now certainly upwards, and let’s not forget that this wasn’t always true. The PHP community has learned its lessons from the past, whilst the language maintains the flexibility to write what is bad.

This book will seek to impart strong software engineering skills to you with the focus on implementing them in PHP. At the time of publishing this book, there is a certain void and a necessity for this kind of material. This book seeks to be the lighthouse that will not only demonstrate software design theory, but also seek to impart practical information of real value to improve the quality and maintainability of the code you write. This book leaves no stone unturned throughout the software development cycle and will seek to confront the reasons as to why the majority of software projects fail whilst also addressing design, redesign, and safeguard effective code.

This book goes beyond traditional design patterns as envisaged by the Gang of Four and details the practices that passionate PHP developers need to be successful as software engineers or leads on detailed PHP projects. This book will introduce you to the core knowledge required to understand project management techniques, why the majority software development projects fail, and why you can make yours a success.

Originally, I gave thought to writing a book on PHP when Mandi Rose, who I worked with previously, suggested I put together a book on the practices I’ve learned with PHP. Needless to say, at the time that suggestion was made, the best of my career was undoubtedly ahead of me; when the opportunity actually arose to write something like this, I felt I had learned dramatically more as time progressed. By no means should you see this book as the be-all and end-all of PHP practices; instead, you should use it to increase your knowledge base on PHP, but by no means limit it to this. In this book, I aim to give something, however small, back to the PHP community; after reading this book, I would encourage you to get stuck in and share what you’ve learned with others.

Later in this book, I will advocate Extreme Programming as a methodology and courage as a key value of this methodology. I will ask you to bear in mind the explanation of courage in The Values of Extreme Programming: We will tell the truth about progress and estimates. We don't document excuses for failure because we plan to succeed. We don't fear anything because no one ever works alone. We will adapt to changes whenever they happen. This is, of course, some key advice we should all follow and seek to genuinely understand risks instead of cowering behind them. For many of us, the code we write during parts of our career is the highest expression of our labor. Indeed, the late nights turning into early mornings we spend debugging and developing are what ultimately allow us to demonstrate the fruits of our labor. In essence, as software engineers, the code we write defines who we are, as such we should be open to constantly refining and refactoring our processes, which is what this book aims to support you in doing. I am incredibly honored that you chose to allow me to help you to reach this end.

What this book covers

Chapter 1, Why Good PHP Developer Isn't an Oxymoron, introduces the concept of design patterns as recurring solutions to commonly arising problems.

Chapter 2, Anti-Patterns, introduces how patterns can lead to decidedly negative consequences.

Chapter 3, Creational Design Patterns, discusses Gang of Four design patterns, namely those surrounding object creation.

Chapter 4, Structural Design Patterns, covers how multiple classes and objects can be combined to deliver a clearer interface.

Chapter 5, Behavioral Design Patterns, explains how to increase the flexibility of communication between objects by identifying patterns that can help with communication between them.

Chapter 6, Architectural Patterns, revolves around resolving common issues related to the architecture of a web application/system, potentially outside the code base itself.

Chapter 7, Refactoring, shows how to redesign code that has already been written to improve maintainability.

Chapter 8, How to Write Better Code, covers a range of concepts that haven’t been discussed elsewhere, and it also concludes with some advice for developers.

What you need for this book

An installation of PHP 7 will serve you well throughout this book. You should be prepared to alter your development environment as needed throughout this book; we will address the installation of various tools as we encounter them.

This book is not for the despairingly hostile or those who are passively antagonistic to approaching new software engineering principles. It is not for those who seek to be lone warriors, either. When altering a given code base, you must seek to improve the code of the entire code base and everyone who works on it. You must be willing to take personal responsibility of the code you write and not blame external factors. Code maintainability cannot be improved unilaterally on shared code bases; you must write your code with the intention of maintaining code quality for those who maintain it after you. Additionally, seek to go into this book with the mindset of being able to share what you’ve learned, whether it is with those in your teams, your user groups, or the larger PHP community. In other words, approach this book with the end in mind; approach this book with the stated aim of improving your code and those in the code base you maintain.

Who this book is for

This book is certainly aimed at the PHP developer looking to learn about the complete set of skills needed to be a software engineer, in particular, some lessons from software design; this book will seek to educate you on how your code can be made more extensible and easier to develop on. This book seeks to take your code beyond just being a bag of functions and classes, instead preferring well-designed, well-written, and well-tested code.

You will need a working knowledge of PHP and enough to build an application, but by no means do you have to be a total expert at everything in PHP; a working knowledge of the basics of software engineering will certainly give you a heads up.

You must encounter this book with an open mind and a willingness to have your preconceptions about software development challenged. This book will confront some truths about how you may be failing personally as a developer; it is vital that you approach this book with a willingness to take these principles onboard.

This book presents a set of software development patterns and principles that you can adopt. It is vital that you understand where these patterns should and shouldn’t be applied; this will be explained throughout the book, especially in the last chapter.

A key tenet of reading this book is understanding what PHP is for and what it isn’t. I expect you to enter this book understanding what problems you expect PHP to solve and what you expect to use other software development languages to solve.

Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: The index.php file now yields this result.

A block of code is set as follows:

abstract class Notifier

{

protected $to;

public function __construct(string $to)

{

$this->to = $to;

}

abstract public function validateTo(): bool;

abstract public function sendNotification(): string;

}

Any command-line input or output is written as follows:

echo $richard->hasPaws;

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: direct your web browser to your chosen web server and you should see Hello world! pop up on screen.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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