Beginning Ruby From Novice to Professional

658 Pages·2009·11.23 MB·English

by  Peter Cooper

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Beginning Ruby: From Novice to Professional, RRuubbyy 11..99!!
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Beginning
Beginning
Dear Reader,
R
Beginning Ruby is the only book you’ll need to go from not knowing Ruby at all
to being proficient and confident enough to develop your own applications and
learn more about the specific areas that interest you. With just this book, you’ll
Ruby
learn how to develop your own complete applications that can work online, u
access databases, process files, and more.
Thanks to the popularity of the Ruby on Rails web application framework,
Ruby has rapidly become a major programming language in the last ten years,
b
roughly on a par with Python. Ruby is still growing and maturing, however, and
now is an especially good time to learn it. I’ve written this book in a way that lets
you quickly learn the language without being bamboozled with jargon, even if
y
you’ve only ever dabbled with programming before. I’ve also provided links to a
multitude of online resources and documentation to help you progress further.
My own Ruby learning experience is my motivation for writing this book. I
wanted to write a book that didn’t assume you’re already a dynamic language or
object-orientation expert. This book introduces the most basic of concepts, yet
moves quickly enough that you won’t need to skip too much if you’re already
familiar with certain areas. Most of the areas relevant to a professional Ruby
developer are covered, too—even those not directly related to the language,
From Novice to Professional
such as database access and SQL.
From the start, my ambition has been to write a book to educate and encour-
age, rather than deliver dry facts. There are enough reference books out there,
but very few that will show you how to program with Ruby in a guided, narrated
way. This book not only shows you how to program with Ruby, it also teaches
you how the Ruby community works, where to find help, and how to “walk the
walk” and “talk the talk.” An instructional guide to the Ruby programming language.
Peter Cooper
Companion eBook
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SOURCE CODE ONLINE C Peter Cooper
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Beginning Ruby
From Novice to Professional
S e
econd dition
Peter Cooper
Beginning Ruby: From Novice to Professional, Second Edition
Copyright © 2009 by Peter Cooper
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For Laura and Penny
Contents at a Glance
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxi
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxv
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxix
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi
PART 1 n n n Foundations and Scaffolding
ChaPtER 1 Let’s Get It Started: Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
ChaPtER 2 Programming == Joy: A Whistle-Stop Tour of Ruby
and Object Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
ChaPtER 3 Ruby’s Building Blocks: Data, Expressions, and Flow Control . . . . .31
ChaPtER 4 Developing Your First Ruby Application . . . . . . . . . . . . . . . . . . . . . . . . . . 77
ChaPtER 5 The Ruby Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
PART 2 n n n The Core of Ruby
ChaPtER 6 Classes, Objects, and Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
ChaPtER 7 Projects and Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
ChaPtER 8 Documentation, Error Handling, Debugging, and Testing . . . . . . . .177
ChaPtER 9 Files and Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
ChaPtER 10 Deploying Ruby Applications and Libraries . . . . . . . . . . . . . . . . . . . . .247
ChaPtER 11 Advanced Ruby Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .275
ChaPtER 12 Tying It Together: Developing a Larger Ruby Application . . . . . . . .307
PART 3 n n n Ruby Online
ChaPtER 13 Web Application Frameworks: Rails, Sinatra, and Ramaze . . . . . . . 349
ChaPtER 14 Ruby and the Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .413
iv
ChaPtER 15 Networking, Sockets, and Daemons . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
ChaPtER 16 GUI-Based Desktop Application Development . . . . . . . . . . . . . . . . . . . 467
ChaPtER 17 Useful Ruby Libraries and Gems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .495
aPPENDIX a Ruby Primer and Review for Developers . . . . . . . . . . . . . . . . . . . . . . . . 547
aPPENDIX B Ruby Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575
aPPENDIX C Useful Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .589
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .601
v

Contents
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxi
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxv
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxix
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxi
PART 1 n n n Foundations and Scaffolding
ChaPtER 1 Let’s Get It Started: Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . .3
Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Apple Mac OS X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Other Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
ChaPtER 2 Programming == Joy: a Whistle-Stop tour of Ruby
and Object Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Baby Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
irb: Interactive Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Ruby Is English for Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Why Ruby Makes a Great Programming Language . . . . . . . . . . . . . .15
Trails for the Mind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Turning Ideas into Ruby Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
How Ruby Understands Concepts with Objects and Classes . . . . . . 17
The Making of a Man . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Basic Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
From People to Pets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
vii
viii nCONTENTS
Everything Is an Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Kernel Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Passing Data to Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Using the Methods of the String Class . . . . . . . . . . . . . . . . . . . . . . . . . 26
Using Ruby Without Object Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
ChaPtER 3 Ruby’s Building Blocks: Data, Expressions, and
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Numbers and Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Basic Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Comparison Operators and Expressions . . . . . . . . . . . . . . . . . . . . . . .33
Looping Through Numbers with Blocks and Iterators . . . . . . . . . . . .35
Floating Point Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Text and Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
String Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
String Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Interpolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
String Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Regular Expressions and String Manipulation . . . . . . . . . . . . . . . . . . . 44
Arrays and Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Basic Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Splitting Strings into Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
Array Iteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Other Array Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Hashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Basic Hash Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
Hashes Within Hashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
if and unless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
?, the Ternary Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
elsif and case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
while and until . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Code Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
Other Useful Building Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Dates and Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Large Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70