Professional .NET 2.0 Generics

410 Pages·2005·5.209 MB·English

by  Tod Golding

01_559885 ffirs.qxd 9/8/05 11:01 PM Page i
Professional .NET 2.0 Generics
Tod Golding
01_559885 ffirs.qxd 9/8/05 11:01 PM Page i
Professional .NET 2.0 Generics
Tod Golding
01_559885 ffirs.qxd 9/8/05 11:01 PM Page ii
Copyright © 2005 by Wiley Publishing Inc. All rights reserved.
Published by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form
or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as
permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior
written permission of the Publisher, or authorization through payment of the appropriate per-copy fee
to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA01923, [phone], fax
[phone]. Requests to the Publisher for permission should be addressed to the Legal Department,
Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, [phone], fax (317)
572-4355,or online at http://www.wiley.com/go/permissions.
LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR
MAKE NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR
COMPLETENESS OF THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL
WARRANTIES, INCLUDING WITHOUT LIMITATION WARRANTIES OF FITNESS FOR APARTIC-
ULAR PURPOSE. NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES OR PROMO-
TIONAL MATERIALS. THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE
SUITABLE FOR EVERYSITUATION. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT
THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR OTHER PRO-
FESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A
COMPETENT PROFESSIONALPERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOT
THE AUTHOR SHALLBE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN
ORGANIZATION OR WEBSITE IS REFERRED TO IN THIS WORK AS ACITATION AND/OR A
POTENTIALSOURCE OF FURTHER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR
THE PUBLISHER ENDORSES THE INFORMATION THE ORGANIZATION OR WEBSITE MAY
PROVIDE OR RECOMMENDATIONS IT MAYMAKE. FURTHER, READERS SHOULD BE AWARE
THAT INTERNET WEBSITES LISTED IN THIS WORK MAYHAVE CHANGED OR DISAPPEARED
BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ.
For general information on our other products and services please contact our Customer Care Depart-
ment within the United States at [phone], outside the United States at [phone] or fax (317)
572-4002.
Trademarks: Wiley, the Wiley Publishing logo, Wrox, the Wrox logo, and Programmer to Programmer
are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates. All other
trademarks are the property of their respective owners. Wiley Publishing, Inc., is not associated with
any product or vendor mentioned in this book.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print
may not be available in electronic books.
Library of Congress Cataloging-in-Publication Data
ISBN-13: 978-0-7645-5988-4
ISBN-10: 0-7645-5988-5
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
01_559885 ffirs.qxd 9/16/05 9:35 AM Page iii
About the Author
Tod Goldinghas 20 years of experience as a software developer, lead architect, and development man-
ager for organizations engaged in the delivery of large-scale commercial and internal solutions. He has
an extensive background leveraging .NET, J2EE, and Windows DNAtechnologies, which has allowed
him to become equally skilled with C#, Java, and C++. Tod has worked and consulted at a variety of
companies, including stints with Microsoft and Borland.
Tod has a B.S. in Computer Science from California State University, Sacramento. He started his writing
career as a journalist for the Sacramento Beedaily newspaper. Prior to this book, he was also a contributing
author for the XMLProgramming Bible, another Wiley publication. Tod currently resides in Sacramento,
California, where he owns and operates Blue Puma Software.
Credits
Vice President and Executive Group Publisher: Development Editor:
Richard Swadley Sharon Nash
Vice President and Publisher: Production Editor:
Joseph B. Wikert Felicia Robinson
Acquisitions Editor: Technical Editor:
Jim Minatel Mark A. Strawmyer
Editorial Manager: Text Design & Composition:
Mary Beth Wakefield Wiley Composition Services
Senior Production Editor:
Tim Tate
01_559885 ffirs.qxd 9/8/05 11:01 PM Page iv
01_559885 ffirs.qxd 9/8/05 11:01 PM Page v
Acknowledgments
Even though my name stands alone on the cover of this book, it certainly couldn’t have come to life
without the support, encouragement, hard work, and creative input of many others.
My family has to be at the top of the list of those that deserve thanks. The sacrifices made by my wife,
Janine, during the past year were nothing short of heroic. Her support never waned, and I could not
have finished this project without her. Thanks, too, to my children, Chelsea and Ryan, who always
showed interest in my progress. Their smiling faces were always a great source of inspiration.
I’d also like to thank everyone at Wiley Publishing. Without Jim Minatel’s insight and guidance, this
book could not have gotten off the ground. His flexibility and willingness to work with a moving target
provided me with the freedom this topic needed. I also can’t go without mentioning Wiley’s Sharon Nash
and Felicia Robinson, who managed all the logistics associated with editing this book. Thanks, too, to
Mark A. Strawmyer for all of his contributions on the technical editing front.
There are also all those who helped push me along during the genesis of this book. My long-time friend,
Bill Clark, provided perspective and creative influence that helped shape my approach to generics.
Finally, special thanks go to Mike Cohn, who has always pushed me to take on new challenges. His early
prodding and mastery of the 100-hour workweek clearly had the single greatest impact on getting me
moving on this project.
01_559885 ffirs.qxd 9/8/05 11:01 PM Page vi
02_559885 ftoc.qxd 9/8/05 11:02 PM Page vii
Contents
Acknowledgments v
Introduction xv
Chapter 1: Generics 101 1
Why Generics? 1
Enter Generics 7
Hello Generics 10
A More Conceptual View 12
Terminology 14
Type Parameters 14
Open Types 15
Constructed Types 15
Type Arguments 15
Open and Closed Constructed Types 15
Generic Methods 16
Type Instantiation 16
Arity 17
Generic Types 17
Bringing It All Together 17
Summary 17
Chapter 2: Valuing Type Safety 19
Motivation 19
Least Common Denominator Programming 20
A Basic Example 21
Applying Generics 26
Casting Consequences 29
Interface Type Safety 31
Scratching the Surface 32
Safety vs. Clarity 32
Summary 33
Chapter 3: Generics ≠ Templates 35
Shared Concepts 35
Run-Time vs. Compile-Time 36
02_559885 ftoc.qxd 9/8/05 11:02 PM Page viii
Contents
Compile-Time Instantiation (Templates) 36
Run-Time Instantiation (Generics) 37
Lost in Translation 38
The Brouhaha 42
Code Bloat 42
Assemblies and Type Equivalence 42
Templates Extras 43
Template Specialization 43
Non-Type Parameters 44
Type Parameter Inheritance 44
Cross-Language Support 44
Debugging 44
Mix and Match Nirvana 44
Summary 45
Chapter 4: Generic Classes 47
Parameterizing Types 47
Type Parameters 49
Overloaded Types 50
Static Constructors 51
Inheritance 52
Protected Members 55
Fields 56
Static Fields 57
Constructed Fields 59
Methods 60
Overloading Methods 61
Overriding Methods 63
Arrays of Type Parameters 65
Operator Overloading 66
Nested Classes 67
Consuming Generic Classes 69
Accessibility 70
The Default Keyword 73
System.Nullable<T> 74
Accessing Type Info 76
Indexers,Properties,and Events 77
Generic Structs 80
Generic Interfaces 81
Summary 82
viii