This document provides an introduction and overview of Ruby and the Rails web framework. It outlines what Ruby and Rails are, why they are useful, and some of their major features. The document demonstrates Ruby concepts like objects, classes, and blocks through interactive examples. It also provides a brief demo of generating a TODO list application in Rails. Finally, it recommends resources for learning more about Ruby and Rails.

1. An Introduction to
Ruby and Rails
Matthew Bohnsack
Wannabe Rubyist
November 9th 2005

2. Outline
 What is Ruby and why should I care?
 What is Rails and why should I care?
 Two must-have tools for Ruby development
 Major Ruby features (the language in a nutshell)
 Rails overview
 Where to go for more information
 Questions / Hacking
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3. What is Ruby? Why should I care?
 What:
 The Wikipedia answer is here.
 Created/lead by Matz (Japanese)
 Open Source interpreted scripting language, like Perl, Python,
Tcl, etc., but focused on being very object oriented, expressive,
and bringing joy to programming.
 Principle of least surprise
 Why:
 Productivity ideas presented in Ousterhout’s 1998 paper coming
to very serious critical mass (and beyond)
 Learn a new language to learn new ways of thinking about code
in any language (e.g., blocks and iterators)
 Joy!
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4. What is Rails? Why should I care?
 What:
 Web Framework that makes building database-driven MVC-oriented web apps
easy through a template engine, ORM (ActiveRecord) and other best practices,
such as test driven development, deployment tools, patterns, etc.
 Much less complicated than J2EE solutions, but perhaps more so than PHP or
Perl in cgi-bin.
 Copy cats are being created in other languages:
 Python (TurboGears)
 Perl (Maypole)
 http://rubyonrails.org/ + book + online screencasts + online docs & tutorials
 Why:
 I’ve been watching the world of web development since ~ 1995, and I’ve never
seen anything like Rails in terms of buzz, momentum, adoption rate, etc.
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5. Must have tool #1: irb
# ~/.irbrc
 Interactive ruby console: require 'irb/completion'
use_readline=true
 Experimenton the fly auto_indent_mode=true
 Tab complete object methods
…
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6. Must have tool #2: ri
 Console-based Ruby doc tool
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7. Ruby in a nutshell – irb sessions
follow
 Like all interpreted scripting languages, you can
put code into a file, chmod +x, then just execute
it.
 But, we’ll mostly use irb sessions in this
presentation…
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8. Ruby in a nutshell – objects are
everywhere
 Some languages have built-in types that aren’t
objects. Not so with Ruby. Everything’s an
object:
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9. Ruby in a nutshell – objects have
methods
Bang on the tab key in irb to see the methods that are available for
each object.
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10. Ruby in a nutshell – Variables
 Local variables - start with lower case:
 foo
 bar
 Global variables - start with dollar sign:
 $foo
 $bar
 Constants and Classes – start with capital letter:
 CONSTANT
 Class
 Instance variables – start with at sign:
 @foo
 @bar
 Class variables – start with double at sign:
 @@foo
 @@bar
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11. Ruby in a nutshell – Arrays
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12. Ruby in a nutshell – Hashes
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13. Ruby in a nutshell – Symbols
 Starts with a ‘:’
 Only one copy of a symbol kept in memory
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14. Ruby in a nutshell – Blocks & Iterators
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15. Ruby in a nutshell – It’s easy to build
classes
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16. Ruby in a nutshell – It’s fun to play with
classes (like the one we just made)
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17. Ruby in a nutshell – Classes are open
 Example shown here uses our Hacker
class, but what happens when the whole
language is open?
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18. Ruby in a nutshell – Other notes on
Classes
 Ruby only has single inheritance. This
makes things simpler, but mix-ins provide
much of multiple inheritance’s benefit,
without the hassle.
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19. Ruby in a nutshell – a few gotchas
 Despite the principle of least surprise:
 Zero isn’t false:
 No increment operator (foo++). Instead use:
 foo += 1
 foo = foo + 1
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20. Ruby in a nutshell – RubyGems
 CPAN for Ruby?
http://docs.rubygems.org/
 Examples:
 gem list
 gem install redcloth --version ">= 3.0.0"
…
 Using gems in your program:
 require ‘rubygems’
 require ‘some_gem’
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21. Want to learn more Ruby?
 Excellent, simple, beginner’s tutorial:
 http://www.math.umd.edu/~dcarrera/ruby/0.3/index.html
 Other stuff at end of talk
 Start hacking
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22. Quick Rails Demo – Build a TODO
list application in 5 minutes
 Define database
 rails todo
 cd todo
 Edit config/database.yml
 ./script/generate model Todo
 ./script/generate scaffold todo
 Look at scaffolding
 ./script/server –b www.bohnsack.com
 Add due_date field, regenerate scaffolding, and check the results
 ./script/console
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23. Where to go for more information
 Books:
 Online material:
 First edition of Pickaxe online for free
 http://www.ruby-doc.org/
 why’s (poignant) guide to Ruby
 http://rubyonrails.org/
 Rails screencast(s)
 Planet Ruby on Rails
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24. The End / Questions
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