Object-oriented PHP : concepts, techniques, and code

216 Pages·2006·4.063 MB·English

by  Peter Lavin

LLEEAARRNN TTHHEE
BBAASSIICCSS OOFF ®
OOBBJJEECCTT--OORRIIEENNTTEEDD
PPRROOGGRRAAMMMMIINNGG
AANNDD PPHHPP
OO
Trying to learn the concepts of object-oriented • Use XML easily with an object-oriented approach
BB
programming using a language like C++ can be an
• Employ PHP to autogenerate documentation for
intimidating experience. The simpler object model of your code JJ
PHP makes it the ideal language for an introduction to EE
object-oriented programming. • Make thumbnail images on the fly
CC
For the uninitiated, this guide to the latest version of • Replace clumsy error trapping with Exception
TT
PHP offers a speedy introduction to object-oriented handling
--
programming, including a thorough explanantion of
• Take full advantage of advanced OO features in PHP
class as well as coverage of constructors, destructors, OO
inheritance, polymorphism and interfaces. In this easy Object-Oriented PHP will show you how to maximize
RR
to follow guide, the author teaches by example, and PHP’s features, with much less work than you might think.
couples new concepts with snippets of example code With Object-Oriented PHP, you can master the basics of II
(which are available for download from the book’s OOP and get up to speed on PHP in one fell swoop. EE
companion website).
ABOUT THE AUTHOR NN
With Object-Oriented PHP, you’ll learn to:
Peter Lavin runs a web development firm based in TT
• Promote code reuse by creating your own classes Toronto, Canada, and he writes regularly on all things EE
and using built-in classes tech. He has been published in a number of magazines
DD
and online publications, including UnixReview.com,
• Customize and improve classes through inheritance
Spider Magazine and PlugIn Magazine. He is also a
PP
• Simplify database access by developing MySQL contributor to the forthcoming PHP Hacks (O’Reilly).
database and result set classes HH
• Incorporate an RSS reader into your site using only PP
four lines of code
OOBBJJEECCTT--OORRIIEENNTTEEDD
PPHHPP
L
A
V
I
THE FINEST IN GEEK ENTERTAINMENT™ $39.95 ($51.95 CDN) N
® www.nostarch.com WEB PROGRAMSHELVE IN: C O N C E P T S , T E C H N I Q U E S , A N D C O D E
“I LAY FLAT.” MIN
G
This book uses RepKover—a durable binding that won’t snap shut. ®
P E T E R L A V I N

OBJECT-ORIENTED
PHP
Concepts, Techniques,
and Code
by Peter Lavin
®
San Francisco
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: [phone]; fax: [phone]; [e-mail]; 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
No Starch Press, Copyright © 2006 by Peter Lavin
B R I E F C O N T E N T S
Acknowledgments........................................................................................................xiii
Introduction...................................................................................................................xv
Chapter1: What a Tangled Web WeWeave....................................................................1
Chapter2: Basics of Object-Oriented Programming............................................................5
Chapter3: Object-Oriented Features New to PHP 5..........................................................11
Chapter4: Show a Little Class........................................................................................17
Chapter5: Mod UR Class..............................................................................................25
Chapter6: The ThumbnailImage Class.............................................................................35
Chapter7: Building the PageNavigatorClass...................................................................47
Chapter8: Using the PageNavigator Class......................................................................57
Chapter9: Database Classes.........................................................................................65
Chapter10: Improvement Through Inheritance..................................................................75
Chapter11: Advanced Object-Oriented Programming Concepts........................................91
Chapter12: Keeping It Fresh..........................................................................................99
Chapter13: More Magic Methods................................................................................111
Chapter14: Creating Documentation Using the Reflection Classes....................................125
Chapter15: Extending SQLite......................................................................................139
Chapter16: Using PDO...............................................................................................157
AppendixA: Setting Up PHP 5.....................................................................................165
AppendixB: Conversion Table: PHP 4 and PHP 5...........................................................169
Glossary....................................................................................................................173
Index.........................................................................................................................179
No Starch Press, Copyright © 2006 by Peter Lavin
No Starch Press, Copyright © 2006 by Peter Lavin
C O N T E N T S I N D E T A I L
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
No Starch Press, Copyright © 2006 by Peter Lavin
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
viii Contents in Detail
No Starch Press, Copyright © 2006 by Peter Lavin
Displaying 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
Contents in Detail ix
No Starch Press, Copyright © 2006 by Peter Lavin
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
x Contents in Detail
No Starch Press, Copyright © 2006 by Peter Lavin