Book Image

Modernizing Legacy Applications in PHP

By : Paul Jones
Book Image

Modernizing Legacy Applications in PHP

By: Paul Jones

Overview of this book

Have you noticed that your legacy PHP application is composed of page scripts placed directly in the document root of the web server? Or, do your page scripts, along with any other classes and functions, combine the concerns of model, view, and controller into the same scope? Is the majority of the logical flow incorporated as include files and global functions rather than class methods? Working with such a legacy application feels like dragging your feet through mud, doesn’t it?This book will show you how to modernize your application in terms of practice and technique, rather than in terms of using tools such as frameworks and libraries, by extracting and replacing its legacy artifacts. We will use a step-by-step approach, moving slowly and methodically, to improve your application from the ground up. We’ll show you how dependency injection can replace both the new and global dependencies. We’ll also show you how to change the presentation logic to view files and the action logic to a controller. Moreover, we’ll keep your application running the whole time. Each completed step in the process will keep your codebase fully operational with higher quality. When we are done, you will be able to breeze through your code like the wind. Your code will be autoloaded, dependency-injected, unit-tested, layer-separated, and front-controlled. Most of the very limited code we will add to your application is specific to this book. We will be improving ourselves as programmers, as well as improving the quality of our legacy application.
Table of Contents (35 chapters)
Modernizing Legacy Applications in PHP
Credits
Foreword
About the Author
Acknowledgement
www.PacktPub.com
Preface
Typical Legacy Page Script
Code before Gateways
Code after Gateways
Code after Transaction Scripts
Code before Collecting Presentation Logic
Code after Collecting Presentation Logic
Code after Response View File
Code after Controller Rearrangement
Code after Controller Extraction
Code after Controller Dependency Injection
Index

Review and next steps


When we have completed writing our tests, as briefly outlined in this chapter, we will have created a great trap for future bugs. Each time we run our tests, any changes to the expected behavior will stand out as failures for us to correct. This ensures that as we continue refactoring, we will be doing more good than harm to our legacy codebase as a whole.

In addition, because we now have a working test suite, we can add tests for any new behavior extracted from our legacy codebase into our application classes. Each time we create a new application class method, we will also create a passing test for that method. Each time we modify an application class method, we will run the test suite so that we can find bugs and breaks before they make it into production. We will rejoice when our tests pass, and we will rejoice when they fail; each outcome is a positive sign when it comes to modernizing our legacy application.

With that, we can continue our modernization process....