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Trying to learn the concepts of object-oriented

programming using a language like C++ can be an intimidating experience. The simpler object model of PHP makes it the ideal language for an introduction to object-oriented programming. For the uninitiated, this guide to the latest version of PHP offers a speedy introduction to object-oriented programming, including a thorough explanantion of class as well as coverage of constructors, destructors, inheritance, polymorphism and interfaces. In this easy to follow guide, the author teaches by example, and couples new concepts with snippets of example code (which are available for download from the book's companion website).

With Object-Oriented PHP, you'll learn to:

• Promote code reuse by creating your own classes and using built-in classes • Customize and improve classes through inheritance • Simplify database access by developing MySQL database and result set classes • Incorporate an RSS reader into your site using only four lines of code • Use XML easily with an object-oriented approach • Employ PHP to autogenerate documentation for your code • Make thumbnail images on the fly • Replace clumsy error trapping with Exception handling • Take full advantage of advanced OO features in PHP

Object-Oriented PHP will show you how to maximize

PHP's features, with much less work than you might think. With Object-Oriented PHP, you can master the basics of

OOP and get up to speed on PHP in one fell swoop.

Peter Lavin runs a web development firm based in

Toronto, Canada, and he writes regularly on all things tech. He has been published in a number of magazines and online publications, including UnixReview.com,

Spider Magazine and PlugIn Magazine. He is also a

contributor to the forthcoming PHP Hacks (O'Reilly). www.nostarch.com "I LAY FLAT." This book uses RepKover—a durable binding that won"t snap shut.

THE FINEST IN GEEK ENTERTAINMENT

SHELVE IN:WEB PROGRAMMING

$39.95 ($51.95 CDN)® OOPHP_02.book Page ii Friday, May 5, 2006 2:25 PM

OBJECT-ORIENTED

PHP

Concepts, Techniques,

and Code by Peter Lavin

San Francisco

OOPHP_02.book Page iii Friday, May 5, 2006 2:25 PM OBJECT-ORIENTED PHP. Copyright © 2006 by Peter Lavin.

All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or

mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior

written permission of the copyright owner and the publisher. Printed on recycled paper in the United States of America

1 2 3 4 5 6 7 8 9 10 - 09 08 07 06

No Starch Press and the No Starch Press logo are registered trademarks of No Starch Press, Inc. Other product and

company names mentioned herein may be the trademarks of their respective owners. Rather than use a trademark

symbol with every occurrence of a trademarked name, we are using the names only in an editorial fashion and to the

benefit of the trademark owner, with no intention of infringement of the trademark.

Publisher: William Pollock

Managing Editor: Elizabeth Campbell

Associate Production Editor: Christina Samuell

Cover and Interior Design: Octopod Studios

Developmental Editor: William Pollock

Technical Reviewer: Peter MacIntyre

Copyeditors: Publication Services, Inc. and Sarah Lemaire

Compositor: Riley Hoffman

Proofreader: Stephanie Provines

For information on book distributors or translations, please contact No Starch Press, Inc. directly:

No Starch Press, Inc.

555 De Haro Street, Suite 250, San Francisco, CA 94107

phone: 415.863.9900; fax: 415.863.9950; info@nostarch.com; www.nostarch.com

The information in this book is distributed on an "As Is" basis, without warranty. While every precaution has been

taken in the preparation of this work, neither the author nor No Starch Press, Inc. shall have any liability to any

person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the

information contained in it. Library of Congress Cataloging-in-Publication Data

Lavin, Peter.

Object-oriented PHP : concepts, techniques, and code / Peter Lavin. p. cm.

Includes index.

ISBN 1-59327-077-1

1. PHP (Computer program language) 2. Object-oriented programming (Computer science) I. Title.

QA76.73.P224L38 2006

005.1"17--dc22

2006015309

oophp_TITLE_COPY.fm Page iv Tuesday, May 16, 2006 9:32 AM

BRIEF CONTENTS

Acknowledgments........................................................................................................ xiii

Introduction ...................................................................................................................xv

Chapter 1: What a Tangled Web We Weave....................................................................1

Chapter 2: Basics of Object-Oriented Programming ............................................................5

Chapter 3: Object-Oriented Features New to PHP 5..........................................................11

Chapter 4: Show a Little Class........................................................................................17

Chapter 5: Mod UR Class ..............................................................................................25

Chapter 6: The ThumbnailImage Class.............................................................................35

Chapter 7: Building the PageNavigator Class...................................................................47

Chapter 8: Using the PageNavigator Class ......................................................................57

Chapter 9: Database Classes .........................................................................................65

Chapter 10: Improvement Through Inheritance..................................................................75

Chapter 11: Advanced Object-Oriented Programming Concepts ........................................91

Chapter 12: Keeping It Fresh..........................................................................................99

Chapter 13: More Magic Methods................................................................................111

Chapter 14: Creating Documentation Using the Reflection Classes....................................125

Chapter 15: Extending SQLite ......................................................................................139

Chapter 16: Using PDO...............................................................................................157

Appendix A: Setting Up PHP 5 .....................................................................................165

Appendix B: Conversion Table: PHP 4 and PHP 5...........................................................169

Glossary ....................................................................................................................173

OOPHP_02.book Page v Friday, May 5, 2006 2:25 PM OOPHP_02.book Page vi Friday, May 5, 2006 2:25 PM

CONTENTS IN DETAIL

ACKNOWLEDGMENTS xiii

INTRODUCTION xv

What Does This Book Have to Offer? ....................................................................... xvi

Who Should Read This Book? .................................................................................. xvi

Requirements ......................................................................................................... xvi

Software .................................................................................................. xvi

Skills ........................................................................................................xvii

Overview of Contents .............................................................................................xvii

Companion Website .............................................................................................. xix

Resources ...............................................................................................................xx

Websites ................................................................................................... xx

Books ....................................................................................................... xx

1

WHAT A TANGLED WEB WE WEAVE 1

Do We Really Need Objects? .................................................................................... 2

Just a Scripting Language ............................................................................. 2

Object Orientation Is for Large Software Shops ............................................... 3

Leave Well Enough Alone ............................................................................ 3

Increased Complexity .................................................................................. 3

The PHP Culture ....................................................................................................... 4

2

BASICS OF OBJECT-ORIENTED PROGRAMMING 5

Class ...................................................................................................................... 6

Classes Versus Records ................................................................................ 6

A Cohesive Whole ...................................................................................... 6

Objects Are Instances .................................................................................. 6

Objects Need Access Modifiers ................................................................................. 7

Object Reuse and Inheritance .................................................................................... 7

Multiple Inheritance ..................................................................................... 8

Having Your Cake and Eating It Too .............................................................. 8

Where to Go from Here ............................................................................................ 9

3

OBJECT-ORIENTED FEATURES NEW TO PHP 5 11

Access Modifiers .................................................................................................... 12

Built-in Classes ....................................................................................................... 12

Exceptions ................................................................................................ 12

Database Classes ...................................................................................... 13

OOPHP_02.book Page vii Friday, May 5, 2006 2:25 PM viiiContents in Detail

Web Services ........................................................................................... 13

Reflection Classes ..................................................................................... 14

Iterator ..................................................................................................... 14

Backward Compatibility .......................................................................................... 14

Pass By Reference ..................................................................................... 14

Prognosis ................................................................................................. 15

Where to Go from Here .......................................................................................... 15

Adoption of PHP 5 .................................................................................... 16

Compromise ............................................................................................. 16

4

SHOW A LITTLE CLASS 17

Design .................................................................................................................. 18

Defining the Problem ................................................................................. 18

Not the Da Vinci Code ........................................................................................... 19

The Constructor ......................................................................................... 19

Referencing Instance Variables ................................................................... 20

Wrapper Methods ..................................................................................... 20

Creating an Instance .............................................................................................. 21

What Have You Accomplished? ............................................................................... 23

But Will It Fly? ....................................................................................................... 23

5

MOD UR CLASS 25

Upgrading to PHP 5 ............................................................................................... 26

Access Modifiers ....................................................................................... 26

The Constructor ......................................................................................... 28

Modifying Your Class ............................................................................................. 29

Reconstructing the Constructor .................................................................... 29

Filtering Content ........................................................................................ 31

Resetting the Array .................................................................................... 32

Summary of Changes ............................................................................................. 33

6

THE THUMBNAILIMAGE CLASS 35

What Does a Designer Do? ..................................................................................... 36

Mimicking the Designer ............................................................................. 36

Help from PHP Functions ............................................................................ 36

The ThumbnailImage Class ...................................................................................... 37

Data Members .......................................................................................... 37

Deconstructing the Constructor .................................................................... 37

Two Ways to Construct an Object ............................................................... 38 Internal Behavior - Private Methods ............................................................. 39

Must It Be Private? ..................................................................................... 40

A Helper Method ...................................................................................... 40

Public Methods ......................................................................................... 41

Garbage Collection ................................................................................... 41

OOPHP_02.book Page viii Friday, May 5, 2006 2:25 PM

Contents in DetailixDisplaying the Image ................................................................................. 41

Get and Set Methods ................................................................................. 42

Image Quality ........................................................................................... 42

When to Change the Quality ...................................................................... 43

Displaying a Thumbnail .......................................................................................... 44

Putting It All Together .............................................................................................. 44

Where to Go from Here .......................................................................................... 45

7

BUILDING THE PAGENAVIGATOR CLASS 47

How Will the Navigator Behave? ............................................................................. 47

Different Kinds of Searches ......................................................................... 48

What Will It Look Like? ........................................................................................... 48

The Code .............................................................................................................. 49

The Constructor ......................................................................................... 51

Ain't Misbehavin' ...................................................................................... 52

Other Constructor Method Calls .................................................................. 52

The getNavigator Method ....................................................................................... 54

Move First and Move Previous .................................................................... 54

Main Body of the Navigator ....................................................................... 55

Move Next and Move Last ......................................................................... 56 Current and Total Number of Pages ............................................................ 56

Where to Go from Here .......................................................................................... 56

8

USING THE PAGENAVIGATOR CLASS 57

DirectoryItems Change ............................................................................................ 58

CSS and Reusability ............................................................................................... 58

Paging with Class .................................................................................................. 60

Displaying an Array Slice ........................................................................... 61

Creating the PageNavigator Object ............................................................ 62

Where to Go from Here .......................................................................................... 63

9

DATABASE CLASSES 65

Using What You Know ........................................................................................... 65

One Lump or Two? ................................................................................................. 66

The MySQLConnect Class ....................................................................................... 66

A Class-Conscious Variable ........................................................................ 67

Making Other Connections ......................................................................... 68

You Can Only Get There from Here ............................................................. 68

The MySQLResultSet Class ....................................................................................... 69

Using the Page Navigator ....................................................................................... 70

Ordering, Filtering, and Extracting .............................................................. 71

Traversing the Result Set ............................................................................. 72

Your Navigator Needs Directions ................................................................ 73

Where to Go After the Navigator ............................................................................. 74

OOPHP_02.book Page ix Friday, May 5, 2006 2:25 PM xContents in Detail 10

IMPROVEMENT THROUGH INHERITANCE 75

The Standard PHP Library ........................................................................................ 76

Extending a Class Through Inheritance ...................................................................... 76

The Exception Class ................................................................................... 77

protected ................................................................................................. 77

final ......................................................................................................... 78

More Magic Methods ................................................................................ 78

Replacing Errors with Exceptions .............................................................................. 79

The MySQLException Class ..................................................................................... 80

Changes to the MySQLConnect Class ....................................................................... 81

Prodding Your Class into Action .................................................................. 82

Catching Exceptions ............................................................................................... 83

Implementing an Interface ....................................................................................... 84

Learning About the Iterator Interface ............................................................ 85

Implementation ......................................................................................... 86

Leaving a Method Undefined ...................................................................... 88

Implementation and Access ........................................................................ 88

Iterating Through a MySQLResultSet ............................................................ 89

Where to Go from Here .......................................................................................... 89

11

ADVANCED OBJECT-ORIENTED PROGRAMMING

CONCEPTS 91

Abstract Classes ..................................................................................................... 91

Private Methods Can"t Be Abstract .............................................................. 92

Interface or Pure Abstract Class? ................................................................. 92

Polymorphism ........................................................................................................ 93

Controlling How Functions Are Used ........................................................... 93

Static Classes ........................................................................................................ 94

Static Math Classes ................................................................................... 94

Instances of Static Classes .......................................................................... 95

Preventing Instantiation of a Static Class ....................................................... 96

Design Patterns ...................................................................................................... 96

The Singleton Pattern ................................................................................. 96

Which Implementation? ............................................................................. 98

Where to Go from Here .......................................................................................... 98

12

KEEPING IT FRESH 99

SimpleXML .......................................................................................................... 100

XML ....................................................................................................... 100

RSS ....................................................................................................... 101

Structure of an RSS File ............................................................................ 101

Reading the Feed .................................................................................... 102

Site-Specific Search .............................................................................................. 103

Google API ............................................................................................ 104

AJAX ..................................................................................................... 104

Installing SOAP ....................................................................................... 104

OOPHP_02.book Page x Friday, May 5, 2006 2:25 PM

Contents in DetailxiThe SOAP Extension ................................................................................ 105

A SOAP Client ........................................................................................ 105

Testing the Functionality ........................................................................... 108

Viewing the Results Using AJAX ................................................................ 109

Complex Tasks Made Easy .................................................................................... 110

Would You Want to Do It Procedurally? .................................................................. 110

13

MORE MAGIC METHODS 111

__get and __set .................................................................................................... 112

Is It Worth It? .......................................................................................... 113

__isset and __unset ............................................................................................... 113

__call ................................................................................................................. 114

__autoload .......................................................................................................... 115

__sleep and __wakeup ......................................................................................... 116

__clone ............................................................................................................... 116

Where's Waldo? .................................................................................... 117

clone ..................................................................................................... 118

Aggregate Classes .................................................................................. 119

A Get Method for Object Data Members of an Aggregate Class .................. 121

No Clones Allowed ................................................................................. 122

A Note About Overloading ................................................................................... 122

14

CREATING DOCUMENTATION USING

THE REFLECTION CLASSES 125

What Are the Reflection Classes? ........................................................................... 126

The Reflection Group of Classes ............................................................................. 126

The Reflection Class ................................................................................. 127

The ReflectionClass Class ......................................................................... 128

ReflectionMethod and ReflectionParameter ................................................. 129

Built-in Functions ...................................................................................... 129

What Format Do You Want? ................................................................................. 130

The Documenter Class .......................................................................................... 130

Describing the Documenter Class .............................................................. 130 Describing Methods and Data Members .................................................... 131

The Constructor ....................................................................................... 132

Method and Data Member Modifiers ......................................................... 132

Using the Documenter Class .................................................................................. 134

Creating a Sidebar of Classes and Interfaces ............................................. 134 Formatting Detailed Documentation ........................................................... 134 Formatting Comments for the Documenter ................................................... 136

Reflecting ............................................................................................................ 137

15

EXTENDING SQLITE 139

Brief Overview ..................................................................................................... 140

Directory Structure ................................................................................................ 140

OOPHP_02.book Page xi Friday, May 5, 2006 2:25 PM xiiContents in Detail

How It's Done ...................................................................................................... 141

Getting Started .................................................................................................... 141

Creating a Table .................................................................................................. 142

Views ................................................................................................................. 143

Triggers .............................................................................................................. 144

PHP Implementation of SQLite ................................................................................ 145

Extending SQLiteDatabase .................................................................................... 145

Override the Query Methods ................................................................................. 146

Error Messages ....................................................................................... 147

Query Methods ....................................................................................... 148

Utility Methods ..................................................................................................... 151

Getting Metadata .................................................................................... 152

Using Metadata ...................................................................................... 153

User-Defined Functions .......................................................................................... 154

Uses and Limitations of SQLite ............................................................................... 156

16

USING PDO 157

Pros and Cons ..................................................................................................... 158

Converting the SQLite Application .......................................................................... 158

Code Changes ....................................................................................... 158

Additional Capabilities of PDO .............................................................................. 161

The PDO Class ........................................................................................ 161

PDOStatement ........................................................................................ 161

Assessment .......................................................................................................... 164

Is It the Holy Grail? .................................................................................. 164

A

SETTING UP PHP 5 165

php.ini Settings .................................................................................................... 166

E_STRICT ................................................................................................ 167

Don't Escape Twice ................................................................................. 168

B

CONVERSION TABLE: PHP 4 AND PHP 5 169

GLOSSARY 173

INDEX 179

OOPHP_02.book Page xii Friday, May 5, 2006 2:25 PM

ACKNOWLEDGMENTS

Special thanks to my family for their support, encouragement, and forbearance; to the folks at No Starch for so deftly smoothing over the rough edges; and lastly, thanks to Rasmus Lerdorf, creator of PHP. OOPHP_02.book Page xiii Friday, May 5, 2006 2:25 PM OOPHP_02.book Page xiv Friday, May 5, 2006 2:25 PM

INTRODUCTION

A number of years ago, before I started using PHP, I created dynamic web pages using C. This really wasn't too different from some of the other options available at the time, though it seems almost unthinkable now.

Creating a dynamic page meant outputting HTML

from your script and recompiling that script if any changes needed to be made. What PHP had to offer was the ability to embed server-side scripts into the body of a page wherever they were needed. This was a considerable improvement because it meant you could code the HTML as HTML and insert scripting when required. Introducing changes was much easier, and since PHP is an interpreted language, there was no need for recompilation. The paths to using PHP are many and varied, but the single most important reason for staying with it is ease of use. This is the major reason that PHP has become such a popular web programming language. With the arrival of version 5, PHP once again makes life simpler for web developers. You can now add the power of a robust but uncomplicated object-oriented (OO) language to your arsenal of web development tools. OOPHP_02.book Page xv Friday, May 5, 2006 2:25 PM xviIntroduction

What Does This Book Have to Offer?

This book teaches OO PHP by doing it. If you are a PHP programmer who wants to make the switch to an OO approach, Object-Oriented PHP can ease the transition from procedural to object-oriented programming (OOP). Basic concepts are introduced using simple but useful classes. In short, this book: ?Brings together information from a variety of sources for a comprehen- sive overview of OO PHP ?Explains OO concepts through concrete examples, not in the abstract ?Takes a practical and easy-to-understand approach ?Demonstrates the advantages of OOP rather than just asserting them The classes developed in this book are fully functional and are all available for download at the companion website. This code can be put to work immediately in a variety of situations. The code takes full advantage of the capabilities of PHP 5 but, where possible, a PHP 4 version of the code is also provided, because you don"t always have a choice about where your code is deployed. Additionally, this will ease the transition for anyone already familiar with OOP under PHP 4.

Who Should Read This Book?

This book will appeal to the developer who is familiar with PHP and wants to learn how to use its OO capabilities. However, programmers already familiar with an OO language, such as Java, who want to learn a scripting language will also find it useful. Additionally, if you are a system administrator who is consid- ering installing PHP 5, this book will help you make an informed decision. PHP is first and foremost a language for creating dynamic web pages, but the relative simplicity of OOP in PHP makes it an ideal language for a general introduction to OOP. The concepts learned here are applicable to any OO language, so if you want to get a feel for OOP, OO PHP is a good place to begin. Whatever your motivation, by the time you"ve finished this book you"ll have an excellent understanding of OOP and numerous classes that can easily be reused in a variety of circumstances. But, more importantly, you"ll be able to create your own classes and extend existing ones.

Requirements

In order to get the maximum benefit from this book, there are software and skill prerequisites.

Software

With one or two minor exceptions (they are noted in the text), all the code in this book will run on PHP 5.0.4 and higher. The PHP 4 code will run just fine under PHP 5 but will issue warnings if error reporting is set to

E_STRICT.

(See Appendix A for more information about this new error reporting level.) OOPHP_02.book Page xvi Friday, May 5, 2006 2:25 PM

Introductionxvii

PHP is available for virtually any operating system, so there are no restrictions in this regard. As far as databases are concerned, any recentquotesdbs_dbs20.pdfusesText_26

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