jRuby: The best of both worlds

A brief introduction to ruby and jRuby, and how to access the java from ruby and visa versa.

Transcript

1. jRuby The best of both worlds Christopher Spring Tuesday 27 March 12
2. @autonomous Tuesday 27 March 12
3. Confessions of a... Rubyist Tuesday 27 March 12
4. Tuesday 27 March 12
5. Brief history of Tuesday 27 March 12
6. Yukihiro “Matz” Matsumoto Tuesday 27 March 12
7. Yukihiro “Matz” Matsumoto “I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python...” Tuesday 27 March 12
8. “[We] need to focus on humans, on how humans care about doing programming... We are the masters. They are the slaves.” Tuesday 27 March 12
9. Tuesday 27 March 12
10. “I hope to see Ruby help every programmer in the world be productive, and to enjoy programming, and to be happy. This is the primary purpose of Ruby language” Tuesday 27 March 12
11. A primer Tuesday 27 March 12
12. # booleans truth = true lies = false # Strings dude = 'Matz' credo = "#{dude} is nice, so we are nice!" # Numbers 42 ** 13 53.8 / 9 19 % 3 Tuesday 27 March 12
13. # Arrays backpack = [6, 'apple', [true, some_object]] # Hashes hash = { true => 'He loves me!', dude => 'Must obey!', backpack => false } # symbols cities = [:paris, :new_york, :johannesburg] Tuesday 27 March 12
14. Wtf is a symbol? Tuesday 27 March 12
15. coders = [ { 'language' => 'ruby', 'location' => 'johannesburg' }, { 'language' => 'java', 'location' => 'port elizabeth' }, # ... { 'language' => 'ruby', 'location' => 'pretoria' } ] # vs. coders = [ { :language => 'ruby', :location => 'johannesburg' }, { :language => 'java', :location => 'port elizabeth' }, # ... { :language => 'ruby', :location => 'pretoria' } ] Tuesday 27 March 12
16. Cool, what about classes? Tuesday 27 March 12
17. public Class Person { private String firstName, lastName; public Person(String firstName, String lastName){ setFirstName(firstName); setLastName(lastName); } public String getFirstName(){ return firstName; } public String getLastName(){ return lastName; } public String setFirstName(String firstName){ this.firstName = firstName; } public String setLastName(String lastName){ this.lastName = lastName; } } Tuesday 27 March 12
18. class Person attr_accessor :first_name, :last_name def initialize(first_name, last_name) @first_name = first_name @last_name = last_name end end Tuesday 27 March 12
19. class Person attr_accessor :first_name, :last_name def initialize(first_name, last_name) @first_name = first_name @last_name = last_name end end person = Person.new( 'Nick', 'Cave') person.first_name = 'Slick' person.last_name = 'Nave' puts "#{person.first_name} #{person.last_name}" Tuesday 27 March 12
20. Btw, everything is an Object! Tuesday 27 March 12
21. true.class() # => TrueClass false.to_s() # => "false" 5.9.floor() # => 5 3.times{ puts('Hello JUG!') } # => Hello JUG! # => Hello JUG! # => Hello JUG! Tuesday 27 March 12
22. module Earth end Tuesday 27 March 12
23. module Earth end class Person attr_reader :first_name, :last_name def initialize(first_name, last_name) @first_name, @last_name = first_name, last_name end end Tuesday 27 March 12
24. module Earth end class Person attr_reader :first_name, :last_name def initialize(first_name, last_name) @first_name, @last_name = first_name, last_name end end chap = Earth::Person.new('Chandler', 'Bing') chap.first_name # => Chandler Tuesday 27 March 12
25. module RepublicPersonnel def storm_trooper Earth::Person.new('Storm', 'Trooper') end end class CloningVat extend RepublicPersonnel end Tuesday 27 March 12
26. module RepublicPersonnel def storm_trooper Earth::Person.new('Storm', 'Trooper') end end class CloningVat extend RepublicPersonnel end #<Earth::Person @last_name="Trooper", @first_name="Storm"> CloningVat.storm_trooper Tuesday 27 March 12
27. module TehForce def sense '... a disturbance in the force' end end module Earth class Person include TehForce end end Tuesday 27 March 12
28. module TehForce def sense '... a disturbance in the force' end end module Earth class Person include TehForce end end farm_boy = Earth::Person.new('Luke', 'Skywalker') # => '... a disturbance in the force' farm_boy.sense Tuesday 27 March 12
29. def other_days( this_happens, and_that_happens) puts 'The sun rises' puts this_happens puts and_that_happens puts 'The sun sets' end some_days 'I do some work' other_days 'I skip', 'I read a book' def some_days( something_happens ) puts 'The sun rises' puts something_happens puts 'The sun sets' end Tuesday 27 March 12
30. def some_days( something_happens ) puts 'The sun rises' puts something_happens puts 'The sun sets' end Tuesday 27 March 12
31. def some_days( something_happens ) puts 'The sun rises' puts something_happens puts 'The sun sets' end Tuesday 27 March 12
32. def some_days( something_happens ) puts 'The sun rises' puts something_happens puts 'The sun sets' end def some_days puts 'The sun rises' yield puts 'The sun sets' end some_days { puts 'I go to work' } some_days do puts 'I skip' puts 'I read a book' end Tuesday 27 March 12
33. file = File.open('i <3 ruby.txt', 'w') file.puts "... i really do!" file.close Tuesday 27 March 12
34. File.open('i <3 ruby.txt', 'w') do |file| file.puts "... i really do!" end file = File.open('i <3 ruby.txt', 'w') file.puts "... i really do!" file.close Tuesday 27 March 12
35. Rubyists TATFT! describe Calculator do before(:each) do @calc = Calculator.new end context 'Addition' do it 'returns 10 when adding 5 and 5' @calc.add(5,5).should == 10 end it 'returns 0 when adding 5 and -5' do @calc.add(5,-5).should == 0 end end # ... end Tuesday 27 March 12
36. Metaprogramming Tuesday 27 March 12
37. class Person def initialize @height, @weight, @hair_color = 6.2, '70kg', 'brown' end %w(height weight hair).each do |property| define_method("#{property}") do i_var = self.instance_eval("@#{property}") i_var.to_s.upcase end end def method_missing(*args, &block) puts "I dont have #{args[0].to_s.gsub(/_/, ' ')}" end end p = Person.new p.my_height # => 6.2 p.my_weight # => 70KG p.my_hair_color # => BROWN p.your_car_keys # => I dont have your car keys Tuesday 27 March 12
38. Any questions so far? Tuesday 27 March 12
39. A primer Tuesday 27 March 12
40. Tuesday 27 March 12
41. Tuesday 27 March 12
42. or.... Tuesday 27 March 12
43. Demo time!! Tuesday 27 March 12
44. Interactive Ruby $ jirb jruby-1.6.7 :001 > require 'java' => true jruby-1.6.7 :001 > #... Tuesday 27 March 12
45. Ackermann Tuesday 27 March 12
46. class Ackermann def self.ack(m, n) return n + 1 if m.zero? return ack(m - 1, 1) if n.zero? ack( m - 1, ack(m, n - 1) ) end end Tuesday 27 March 12
47. include Rubeus::Swing JFrame.new('Ackerizer') do |frame| frame.layout = java.awt.FlowLayout.new @m, @n = JTextField.new('3'),JTextField.new('10') JButton.new('->') do start = Time.now @result.text = Ackermann.ack( @m.text.to_i, @n.text.to_i ).to_s puts "#{Time.now - start}" end @result = JTextField.new 10 frame.pack frame.show end Tuesday 27 March 12
48. class Ackermann def self.ack(m, n) return n + 1 if m.zero? return ack(m - 1, 1) if n.zero? ack( m - 1, ack(m, n - 1) ) end end Tuesday 27 March 12
49. class Ackermann def self.ack(m, n) return n + 1 if m.zero? return ack(m - 1, 1) if n.zero? ack( m - 1, ack(m, n - 1) ) end end public class Ackermann { public static int ack(int m, int n) { if (m == 0) return n + 1; if (n == 0) return ack(m - 1, 1); return ack(m - 1, ack(m, n - 1)); } } Tuesday 27 March 12
50. include Rubeus::Swing JFrame.new('Ackerizer') do |frame| frame.layout = java.awt.FlowLayout.new @m, @n = JTextField.new('3'),JTextField.new('10') JButton.new('->') do start = Time.now @result.text = Java::Ackermann.ack( @m.text.to_i, @n.text.to_i ).to_s puts "#{Time.now - start}" end @result = JTextField.new 10 frame.pack frame.show end Tuesday 27 March 12
51. Method overloading public class OverloadTypeChecker { public static String inspect(long value) { return "long"; } public static String inspect(String value) { return "string"; } public static String inspect(Object value) { return "object"; } } Tuesday 27 March 12
52. require 'java' java_import 'OverloadTypeChecker' do 'OTC' end # jRuby happily handles the simple case OTC.inspect(5) # long OTC.inspect('Helloooo!') # string OTC.inspect([]) # object Tuesday 27 March 12
53. public class BitLength { public int neededFor(int i) { return 32; } public int neededFor(long l) { return 64; } } Tuesday 27 March 12
54. # jRuby can be forced to use a specific overload require 'java' java_import 'BitLength' bits = BitLength.new bits.needed_for(1_000_000) # 64 Tuesday 27 March 12
55. # jRuby can be forced to use a specific overload require 'java' java_import 'BitLength' bits = BitLength.new bits.needed_for(1_000_000) # 64 # java_send bits.java_send :neededFor, [Java::int], 1_000_000 # 32 Tuesday 27 March 12
56. # jRuby can be forced to use a specific overload require 'java' java_import 'BitLength' bits = BitLength.new bits.needed_for(1_000_000) # 64 # java_alias class BitLength java_alias :needed_for_int, :neededFor, [Java::int] end bits.needed_for_int 1_000_000 # 32 # java_send bits.java_send :neededFor, [Java::int], 1_000_000 # 32 Tuesday 27 March 12
57. # jRuby can be forced to use a specific overload require 'java' java_import 'BitLength' bits = BitLength.new bits.needed_for(1_000_000) # 64 # java_method needed = bits.java_method :neededFor, [Java::int] needed.call 1_000_000 # 32 # java_alias class BitLength java_alias :needed_for_int, :neededFor, [Java::int] end bits.needed_for_int 1_000_000 # 32 # java_send bits.java_send :neededFor, [Java::int], 1_000_000 # 32 Tuesday 27 March 12
58. ... and more about types Tuesday 27 March 12
59. public class TypeChecker{ public static String check(Object o){ return o.getClass().getName(); } } require 'java' ruby_array = [1, 2, 'Mushrooms', :sample] java_array = ruby_array.to_java # org.jruby.RubyArray Java::TypeChecker.check( ruby_array ) # [Ljava.lang.Object; Java::TypeChecker.check( java_array ) # org.jruby.RubyArray Java::TypeChecker.check( java_array.to_a ) Tuesday 27 March 12
60. Sooo, what about those C extensions... ? Tuesday 27 March 12
61. Awesome, but why? • Cross platform GUI dev • Performance • Ruby interface to legacy code • Use a ruby test framework (Seriously, they’re amazing!) • Utilize java libraries • Sneak ruby into a java shop • Threading Tuesday 27 March 12
62. Tuesday 27 March 12
63. import org.jruby.embed.InvokeFailedException; import org.jruby.embed.ScriptingContainer; public class RubyFromJava { public static void main(String[] args) { ScriptingContainer container = new ScriptingContainer(); container.runScriptlet("puts 'Java touched my Ruby'"); } } $ java -cp jruby-complete.jar:. RubyFromJava Java touched my Ruby Tuesday 27 March 12
64. More Demos!! Tuesday 27 March 12
65. http://pragprog.com/book/jruby/using-jruby Tuesday 27 March 12
66. http://www.meetup.com/Code-Coffee-JHB/ Tuesday 27 March 12
67. http://www.meetup.com/RubyOnBeer/ Tuesday 27 March 12
68. Questions? Tuesday 27 March 12