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

Using The __autoload() Function


If we are stuck on PHP 5.0 for some reason, we can use the __autoload() function in place of the SPL autoloader registry. There are drawbacks to doing things this way, but under PHP 5.0 it is our only alternative. We do not need to register it with SPL (in fact, we cannot, since SPL was not introduced until PHP 5.1). We will not be able to mix-and-match other autoloaders in this implementation; only one __autoload() function is allowed. If an __autoload() function is already defined, we will need to merge this code with any code already existing in the function:

setup.php
1 <?php
2 // ... setup code ...
3
4 // define an __autoload() function
5 function __autoload($class)
6 {
7 // ... the global function code ...
8 }
9
10 // ... other setup code ...
11 ?>

I strongly recommend against using this kind of implementation in PHP 5.1 and later.

Autoloader Priority

Regardless of how we implement our autoloader code, we need it to be available before any classes...