Programacion ruby

THE EXPERT’S VOICE ® IN OPEN SOURCE

Beginning

Ruby
From Novice to Professional
An instructional guide to the Ruby programming language.

Peter Cooper
Foreword by why the lucky stiff

Beginning Ruby
From Novice to Professional

Peter Cooper

Beginning Ruby: From Novice to Professional Copyright © 2007 by Peter Cooper
All rights reserved. No part of this work may be reproducedor 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. ISBN-13 (pbk): 978-1-59059-766-8 ISBN-10 (pbk): 1-59059-766-4 Printed and bound in the United States of America 9 8 7 6 5 4 3 2 1 Trademarked names may appear inthis book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Lead Editors: Jonathan Gennick, Keir Thomas Technical Reviewers: Tim Fletcher, Peter Marklund Editorial Board: Steve Anglin, Ewan Buckingham, Gary Cornell, Jason Gilmore,Jonathan Gennick, Jonathan Hassell, James Huddleston, Chris Mills, Matthew Moodie, Jeff Pepper, Paul Sarknas, Dominic Shakeshaft, Jim Sumser, Matt Wade Project Manager: Beth Christmas Copy Edit Manager: Nicole Flores Copy Editor: Susannah Davidson Pfalzer Assistant Production Director: Kari Brooks-Copony Production Editor: Lori Bring Compositor: Gina Rexrode Proofreader: Nancy Sixsmith Indexer:Julie Grady Artist: April Milne Cover Designer: Kurt Krames Manufacturing Director: Tom Debolski Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY 10013. Phone 1-800-SPRINGER, fax 201-348-4505, e-mail orders-ny@springer-sbm.com, or visit http://www.springeronline.com. For information on translations, please contact Apress directlyat 2560 Ninth Street, Suite 219, Berkeley, CA 94710. Phone 510-549-5930, fax 510-549-5939, e-mail info@apress.com, or visit http://www.apress.com. The information in this book is distributed on an “as is” basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect toany loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work. The source code for this book is available to readers at http://www.apress.com in the Source Code/ Download section.

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Contents at a Glance
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . xix About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii About the Technical Reviewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxv Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . xxvii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxix

PART 1
■ CHAPTER 1 ■ CHAPTER 2 ■ CHAPTER 3 ■ CHAPTER 4 ■ CHAPTER 5

■■■

Foundations and Scaffolding

Let’s Get It Started: Installing Ruby . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 3 Programming == Joy: A Whistle-Stop Tour of Ruby and Object Orientation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Ruby’s Building Blocks: Data, Expressions, and Flow Control . . . . . . . . . . 35 Developing a Basic Ruby Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 The Ruby...