Introduction For Ruby On 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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