www.it-ebooks.info Learning Ruby www.it-ebooks.info Other resources from O’Reilly Related titles Ruby Cookbook ™ Ruby in a Nutshell Ruby on Rails: Up and Running Ajax on Rails Rails Cookbook ™ oreilly.com oreilly.com is more than a complete catalog of O’Reilly books. You’ll also find links to news, events, articles, weblogs, sample chapters, and code examples. oreillynet.com is the essential portal for developers interested in open and emerging technologies, including new platforms, pro- gramming languages, and operating systems. Conferences O’Reilly brings diverse innovators together to nurture the ideas that spark revolutionary industries. We specialize in document- ing the latest tools and systems, translating the innovator’s knowledge into useful skills for those in the trenches. Visit conferences.oreilly.com for our upcoming events. Safari Bookshelf (safari.oreilly.com) is the premier online refer- ence library for programmers and IT professionals. Conduct searches across more than 1,000 books. Subscribers can zero in on answers to time-critical questions in a matter of seconds. Read the books on your Bookshelf from cover to cover or sim- ply flip to the page you need. Try it today for free. www.it-ebooks.info Learning Ruby Michael Fitzgerald Beijing • Cambridge • Farnham • Köln • Paris • Sebastopol • Taipei • Tokyo www.it-ebooks.info Learning Ruby by Michael Fitzgerald Copyright © 2007 Michael Fitzgerald. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (safari.oreilly.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or corporate@oreilly.com. Editor: Simon St.Laurent Production Editor: Lydia Onofrei Proofreader: Lydia Onofrei Indexer: John Bickelhaupt Cover Designer: Karen Montgomery Interior Designer: David Futato Illustrators: Robert Romano and Jessamyn Read Printing History: May 2007: First Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. Learning Ruby, the image of a giraffe, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc. was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. This book uses RepKover ™ , a durable and flexible lay-flat binding. ISBN-10: 0-596-52986-4 ISBN-13: 978-0-596-52986-4 [M] www.it-ebooks.info Robert Wayne Darrah 1950–2006 Till we meet again www.it-ebooks.info www.it-ebooks.info vii Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi 1. Ruby Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Hello, Matz 2 Interactive Ruby 12 Resources 13 Installing Ruby 15 Permission Denied 20 Associating File Types on Windows 21 Review Questions 22 2. A Quick Tour of Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Ruby Is Object-Oriented 23 Ruby’s Reserved Words 26 Comments 27 Variables 28 Strings 30 Numbers and Operators 33 Conditional Statements 34 Arrays and Hashes 34 Methods 35 Blocks 40 Symbols 43 Exception Handling 44 Ruby Documentation 45 Review Questions 45 www.it-ebooks.info viii | Table of Contents 3. Conditional Love . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 The if Statement 47 The case Statement 51 The while Loop 52 The loop Method 55 The for loop 56 Execution Before or After a Program 59 Review Questions 59 4. Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Creating Strings 60 Concatenating Strings 63 Accessing Strings 63 Comparing Strings 65 Manipulating Strings 66 Case Conversion 70 Managing Whitespace, etc. 71 Incrementing Strings 73 Converting Strings 74 Regular Expressions 74 1.9 and Beyond 78 Review Questions 78 5. Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Class Hierarchy and Included Modules 80 Converting Numbers 81 Basic Math Operations 81 Ranges 85 Inquiring About Numbers 86 More Math Methods 88 Math Functions 88 Rational Numbers 90 Prime Numbers 91 Review Questions 92 6. Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Creating Arrays 94 Accessing Elements 97 Concatenation 99 www.it-ebooks.info Table of Contents | ix Set Operations 99 Unique Elements 100 Blow Your Stack 100 Comparing Arrays 101 Changing Elements 101 Deleting Elements 103 Arrays and Blocks 103 Sorting Things and About Face 104 Multidimensional Arrays 104 1.9 and Beyond 105 Other Array Methods 105 Review Questions 105 7. Hashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Creating Hashes 107 Accessing Hashes 108 Iterating over Hashes 109 Changing Hashes 110 Converting Hashes to Other Classes 113 1.9 and Beyond 113 Other Hash Methods 114 Review Questions 114 8. Working with Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Directories 115 Creating a New File 117 Opening an Existing File 117 Deleting and Renaming Files 120 File Inquiries 120 Changing File Modes and Owner 121 The IO Class 123 Review Questions 124 9. Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Defining the Class 126 Instance Variables 127 Accessors 129 Class Variables 130 Class Methods 131 www.it-ebooks.info [...]... of open source Ruby projects Some of the more popular projects include Mongrel, a fast HTTP server (http://rubyforge.org/projects/mongrel), RubyGems (http://rubyforge.org/ projects/rubygems), a dead-simple tool for installing Ruby packages, and Instant Rails (http://rubyforge.org/projects/instantrails), a single-step Windows installer that includes Ruby, Rails, Apache, and MySQL The Ruby Application... Now test to make sure Ruby is in place: $ ruby -v 10 You should get this happy reply: $ ruby 1.8.6 (2007-03-13 patchlevel 0) [powerpc-darwin8.9.0] Alrighty then You are ready to roll with Ruby on Mac OS X Installing Ruby on Windows with the One-Click Installer It’s easy to install Ruby on Windows with the One-Click Installer, available on RubyForge at http://rubyforge.org/projects/rubyinstaller Here are... How This Book Is Organized Learning Ruby is organized into 11 chapters A brief synopsis of each follows: Chapter 1, Ruby Basics Introduces many Ruby basics, such as where to get Ruby, how to install it, and how to run a large cross-section of programs to enable you to start using Ruby immediately xii | Preface www.it-ebooks.info Chapter 2, A Quick Tour of Ruby Gallops over the Ruby terrain at a brisk... password: $ sudo make install 16 | Chapter 1: Ruby Basics www.it-ebooks.info The steps to install Ruby are very similar: 1 While in /usr/local/src, grab the archive for the latest version of Ruby (1.8.6 at this writing): $ curl -O ftp://ftp .ruby- lang.org/pub /ruby/ ruby-1.8.6.tar.gz 2 Extract the archive: $ tar xzvf ruby- 1.8.6.tar.gz 3 Change directories: $ cd ruby- 1.8.6 4 Run configure (enabling POSIX... other good stuff Ruby Central, Inc (http://www.rubycentral.org) runs the annual International Ruby Conference (http://www.rubycentral.org/conference) It usually gets sold out way early, so plan accordingly Aside from the documentation page on ruby- lang.org (http://www .ruby- lang.org/en/ documentation), http://www .ruby- doc.org is a great place to hunt down information on all things Ruby RDoc is a tool... sure to enable RubyGems when asked, as it is installed by default, and you’ll no doubt want use it later 3 Select a destination folder (such as C: \Ruby or C:\“Program Files” \Ruby) If you try to install over an older version of Ruby, you’ll be asked to uninstall the old version first 4 Add the new Ruby bin directory to your path; for example, if your Ruby directory is C: \Ruby, add C: \Ruby\ bin to your... if you get a reply like this one (good news if you do): /usr/local/bin /ruby Or just type a command to check the version of Ruby (this works on Unix/Linux and Windows): $ ruby -v or: $ ruby version If Ruby is installed, you should get an answer that looks like this: ruby 1.8.6 (2007-03-13 patchlevel 0) [powerpc-darwin8.9.0] If Ruby is not installed on your box, and you’re a little nervous about figuring... http://www.apple.com/downloads/dashboard/developer/rubyrdocwidget.html Figure 1-4 RDoc widget on Dashboard Ruby- Talk is the most popular general Ruby mail list To sign up (easily), go to http:// www .ruby- lang.org/en/community/mailing-lists You’ll also see several other lists at this site For a more complete list of mail groups, including lists in languages besides English, see http://www .ruby- forum.com RubyForge (http://rubyforge.org)... Installing Ruby on Windows with Binaries Installing Ruby using binaries (precompiled executables) is just as easy as using the One-Click Installer I think it is, anyway Here are the steps I suggest: 1 Decide where you want to install the Ruby files—for example, C: \Ruby or C:\ “Program Files” \Ruby 2 Download the stable binary ZIP archive for the latest release of Ruby (1.8.6 at this writing) Go to the Ruby. .. writing) Go to the Ruby download page at http://www .ruby- lang.org/en/ downloads, and find the Ruby on Windows” section, then click the link Ruby 1.8.6 Binary Or you can just point to ftp://ftp .ruby- lang.org/pub /ruby/ binaries/ mswin32 /ruby- 1.8.6-i386-mswin32.zip (or latest version) in a browser This will download the file archive 3 Open the archive (ruby- 1.8.6-i386-mswin32.zip or later) with Windows . www.it-ebooks.info Learning Ruby www.it-ebooks.info Other resources from O’Reilly Related titles Ruby Cookbook ™ Ruby in a Nutshell Ruby on Rails: Up and Running Ajax. do): /usr/local/bin /ruby Or just type a command to check the version of Ruby (this works on Unix/Linux and Windows): $ ruby -v or: $ ruby version If Ruby is installed,