My slides from the presentation I gave at the Devnology Community Day on 7 November 2009.

1. An Introduction to Ruby

2. Speaker.new({
:name => "Wes Oldenbeuving",
:twitter => "@Narnach",
:rubyist_since => "Early 2006",
:works_as => "Freelance Rubyist",
:code_at => "github.com/Narnach",
:email => "wes@narnach.com"
})

3. Overview
What is Ruby?
History and current versions
What does Ruby look like?
Basic tools of the Rubyist
Practical uses of Ruby
The Ruby Community

4. What is Ruby?

5. Object oriented

6. Everything is an object
1.class # => Fixnum
'a'.class # => String
:z.class # => Symbol
class Foo
end
Foo.class # => Class
Foo.new.class # => Foo

7. Dynamically typed
def foo(bar)
bar * 2
end
foo(1) # => 2
foo("a") # => "aa"

8. Duck Typing
"a".respond_to? :size # => true
1.respond_to? :+ # => true
1.respond_to? :inject # => false

9. Scripting language

10. Everything is an expression

11. Ruby: the history

12. Japan

13. Idea
1993

14. Productivity and fun

15. Focus on the programmer,
not the computer

16. Inspired by
Perl, Smalltalk, Lisp

17. v0.95
1995

18. English-language
1999
v1.3

19. Programming Ruby
2000

20. Current versions of Ruby

21. Matz Ruby Interpreter
Stable Ruby 1.8

22. Yet Another Ruby VM
Development Ruby 1.9

23. JRuby (1.4)
Ruby 1.8 (1.9) on the JVM

24. Rubinius
Ruby 1.8 in Ruby
(and a bit of C++)

25. IronRuby (0.9.2)
Ruby 1.8 without continuations

26. MacRuby (0.5)
Ruby 1.9 in Objective-C

27. Maglev
Ruby in Gemstone Smalltalk VM

28. Ruby: the language

29. What does Ruby look like?

30. Strings and Variables
'Hello, Devnology!'
name = 'Devnology' # => "Devnology"
"Hello, #{name}!" # => "Hello, Devnology!"

31. Methods
str = "Hello, Devnology!"
str.size # => 17
str.sub("Devnology", "World") # => "Hello, World!"
def greet(name="Wes")
"Greetings, #{name}!"
end
puts greet
puts greet('Devnology')
# >> Greetings, Wes!
# >> Greetings, Devnology!

32. Numbers
1 + 2 # => 3
1 + 2.1 # => 3.1
2**10 # => 1024
9 / 2 # => 4
5 % 3 # => 2
-3.abs # => 3
1.class # => Fixnum
(2**50).class # => Bignum
1.3.class # => Float

33. Arrays
Array.new # => []
[1,2,3] # => [1, 2, 3]
[1] + [2] << 3 # => [1, 2, 3]
[1,2,3] - [2,3] # => [1]
%w[one two] # => ["one", "two"]
[1,2,3].pop # => 3
[1,2].push(3) # => [1, 2, 3]
[1,2,3].shift # => 1
[2,3].unshift(1) # => [1, 2, 3]
[1,3].insert(1,2) # => [1, 2, 3]

34. Hashes
options = {:name => "Devnology"}
h = Hash.new # => {}
h['string'] = 1
h[:symbol] = 1
h # => {:symbol=>1, "string"=>1}
h.keys # => [:symbol, "string"]
h[:symbol] # => 1

35. Iterators
for n in 0..2
puts n
end
(0..2).each do |n|
puts n
end
[0,1,2].each {|n| puts n}

36. Enumerable
ary = [1,2,3]
ary.map {|n| n * 2} # => [2, 4, 6]
ary.select {|n| n % 2 == 0} # => [2]
ary.inject(0) {|sum, n| sum + n} # => 6

37. Control structures
if some_condition
# ...
elsif other_condition
# ...
else
# ...
end
while condition
# ...
end
puts "lol" if funny?

38. Regular Expressions
str = "Hello, world!"
str.gsub(/[aeiou]/,"*") # => "H*ll*, w*rld!"
str =~ /w(or)ld/ # => 7
$1 # => "or"
match = str.match(/w(or)ld/) # => #<MatchData:
0x532cbc>
match[0] # => "world"
match[1] # => "or"

39. Error handling
begin
raise "Standard error"
rescue => e
p e
end
# >> #<RuntimeError: Standard error>
begin
raise StandardError.new("Oh, oh")
rescue RuntimeError
puts "runtime"
rescue StandardError
puts "standard"
end
# >> standard

40. System interaction
system "ls"
output = `ls`
ARGV
File.open('test.txt','w') do |file|
file.write("linen")
file.puts("line")
end
File.read('test.txt')

41. Classes
class Calc
attr_accessor :factor
def initialize(factor=2)
@factor = factor
end
def multiply(value)
@factor * value
end
end
calc = Calc.new
calc.multiply 5 # => 10
calc.factor = 3
calc.multiply 5 # => 15

42. Inheritance
class Foo
def greet
"Hi, #{value}"
end
def value
"foo"
end
end
class Bar < Foo
def value
"bar"
end
end
Foo.new.greet # => "Hi, foo"
Bar.new.greet # => "Hi, bar"

43. Mixins & Open Classes
module Even
def even?
self % 2 == 0
end
end
class Fixnum
include Even
end
1.even? # => false
2.even? # => true

44. Class methods
class Foo
def self.bar
"BAR!"
end
def bar
"bar"
end
end
Foo.bar # => "BAR!"
Foo.new.bar # => "bar"

45. Basic tools of a Rubyist

46. Rubygems

47. Rdoc

48. Interactive Ruby

49. Practical uses of Ruby

50. Ruby on Rails
class BlogPost < ActiveRecord::Base
belongs_to :user
has_many :comments
validates_presence_of :user_id
validates_associated :user
validates_length_of :title, :within => 10..100
validates_length_of :body, :within => 100..5000
end
BlogPost.new(:title => "Hello", :body => "foo!")

51. Rspec
it "should be awesome" do
foobar = FooBar.new
foobar.should be_awesome
end

52. Cucumber
Feature: Write blog post
As a blogger
I want to create a new blog post
So that I can share my knowledge
Scenario: Click the Add group button
Given I am on the homepage
When I follow "New post"
Then I should be on the new blog post page
Given /^I am on (.+)$/ do |page_name|
visit path_to(page_name)
end

53. Scripting / automation

54. DSL: Rake
desc "Clean everything up"
task :cleanup do
Cleaner.cleanup!
end
desc "Make sure everything is shiny"
task :shiny => :cleanup do
Shiner.polish!
end

55. DSL: Capistrano
set :application, "blog"
set :repository, "git@github.com:Narnach/#{application}.git"
set :deploy_to, "/var/www/www.#{application}.com"
set :scm, :git
role :web, "server"
role :app, "server"
role :db, "server", :primary => true
namespace :deploy do
desc "Restart Passenger"
task :restart, :roles => :app, :except => { :no_release => true } do
run "touch #{File.join(current_path,'tmp','restart.txt')}"
end
end

56. The Ruby Community

57. Rubyists

58. Amsterdam.rb
Monthly beer night
Presentation nights

59. Utrecht.rb
Monthly beer night

60. rubyists.eu

61. ruby-groups.org
dev-groups.org