Ruby for Java minds

My talk in JRubyConf EU 2013

Transcript

1. RUBY FOR JAVA MINDS
2. $ whoami
3. @janogonzalez
4. @hop_in
5. HISTORY
6. THE 90’S
7. BIG CHANGES
9. COLD WAR IS OVER
11. GRUNGE GOES MAINSTREAM
12. APATHY
13. SELF- ALIENATION
14. ANGST IS THE NEW COOL
15. MEANWHILE IN THE PROGRAMMING WORLD...
16. RAISING AGAINST THE MAINSTREAM
17. JAMES GOSLING
18. JAMES GOSLING
19. JAVA
20. “Write Once, Run Anywhere”
21. THE 5 PRINCIPLES • It should be "simple, object-oriented and familiar" • It should be "robust and secure" • It should be "architecture-neutral and portable" • It should execute with "high performance" • It should be "interpreted, threaded, and dynamic"
22. (THAT WAS NOT RSPEC)
23. MATZ
24. MATZ
25. RUBY
26. “Ruby is designed to make programmers happy”
27. MATZ WINS THE NOBEL PEACE PRICE
28. (HISTORICAL ACCURACY IS OVERRATED)
29. 2 DIFFERENT PHILOSOPHIES
30. HOW DO WE EMBRACE RUBY?
31. MY HISTORY
32. Y2K
33. COMPUTER APOCALYPSE DID NOT HAPPEN
34. I WENT TO A “JAVA SCHOOL”
35. JAVA EE, SPRING AND CUBICLES
36. HEY, RAILS LOOK COOL!
37. HEY, THERE IS A FLY OVER THERE!
38. (STUPID FLY)
39. THE 10’S
40. RAILS VS JAVA EE WAS OVER
41. HEY, RUBY LOOKS COOL!
42. WAIT, HOW DO I DECLARE AN INTERFACE?
44. THE PROBLEM
45. “The determined Real Programmer can write FORTRAN programs in any language.” –Ed Post
46. HOW TO WRITE RUBY THAT FEELS LIKE RUBY?
47. A ZEN MOMENT
48. ॳ৺
49. BEGINNER’S MIND
50. EMPTY YOUR CUP
51. BACK TO BASICS
52. THE KEY TO UNDERSTAND RUBY
53. EXPRESSIONS + OBJECTS
54. SYNTAX IS EXPRESSION-ORIENTED
55. “LISP programmers know the value of everything and the cost of nothing.” - Alan Perlis
56. EXPRESSIONS def average(a, b) (a + b) / 2 end # => nil average(10, 2) # => 6
57. EXPRESSIONS level = case when 1..2 then :excellent when 3..5 then :normal else :bad end
58. ALL VALUES ARE OBJECTS
59. OBJECTS -1.class # => Fixnum
60. OBJECTS String.object_id # => 70138854779960
61. OBJECTS nil.nil? # => true
62. WO IST DEIN GOTT JETZT
63. MESSAGES
64. MESSAGES EVERYWHERE
65. MESSAGES 40 + 2 # => 42
66. MESSAGES 40.+(2) # => 42
67. MESSAGES 40.send(:+, 2) # => 42
68. MESSAGES ≠ METHODS
69. MESSAGES class AccountProtectionProxy def initialize(real_account, owner) @subject = real_account @owner = owner end ...
70. MESSAGES class AccountProtectionProxy ... def method_missing(name, *args) check_access @subject.send(name, *args) end ... end
71. DYNAMIC TYPING
72. FORGET ABOUT JAVA INTERFACES
73. JAVA public interface Report { ReportFile generate(); }
74. JAVA public class PDFReport implements Report { .... }
75. JAVA public class CSVReport implements Report { .... }
76. JAVA public void print(List<Report> reports) { if (reports == null) { return; } for (Report r : reports) { ReportFile file = r.generate(); ... } }
77. DYNAMIC TYPING def print(reports) [*reports].each do |r| file = r.generate ... end end
78. DYNAMIC TYPING class PDFReport def generate ... end ... end
79. DYNAMIC TYPING class CVSReport def generate ... end ... end
80. DYNAMIC TYPING class Duck def generate ... end ... end
81. PROGRAM TO INTERFACES, NOT TO interface
82. USED EVERYWHERE
83. DYNAMIC TYPING "Jano in " << "Berlin" # => "Jano in Berlin" ["Santiago"] << "Berlin" # => ["Santiago", "Berlin"]
84. IF YOU REALLY NEED TO CHECK...
85. DYNAMIC TYPING if report.respond_to?(:generate) report.generate ... else ... end
86. IF YOU REALLY, REALLY NEED TO CHECK...
87. DYNAMIC TYPING if report.is_a?(Report) report.generate ... else ... end
88. DYNAMIC BUT NOT WEAK
89. STRONG TYPING 100 + 'cool' # TypeError: String can't be coerced into Fixnum
90. TYPE CONVERSIONS
91. CONVERSIONS 100 + 'cool'.to_i # => 100 100 + Integer('cool') # ArgumentError: invalid value for Integer(): "lala"
92. BLOCKS
93. BLOCKS ARE USED & ABUSED IN RUBY
94. PROGRAM LIKE A BOSS
95. (LITERALLY)
96. BLOCKS (1..100).select { |n| n % 3 == 0 } .map { |n| n * 2 } .reduce(:+)
97. FLUID CODE
98. BLOCKS File.open('my.txt').each do |line| puts line if line =~ /jano/ end
99. BE MORE DECLARATIVE
100. BLOCKS words.sort do |a, b| a.length <=> b.length end words.min_by? { |w| w.length } words.reject { |w| w.length > 8 } # etc...
101. EXAMPLE: SELF YIELD
102. BLOCKS class Job def initialize yield self if block_given? end ... end
103. BLOCKS job = Job.new do |j| j.name = 'Print Reports' j.user = 'janogonzalez' ... end
104. EXAMPLE: CALLBACKS
105. BLOCKS class Job def on_finish(&block) @end_callback = block end def execute() ... @end_callback.call(self) if @end_callback end end
106. BLOCKS job.on_finish do |j| puts "Finished job #{j.name}" puts "Status: #{j.status}” end
107. MIXINS
108. MODULES AS MIXINS
109. ADD BEHAVIOR TO INSTANCES
110. MODULES module Model def persist ... end end
111. MODULES class User include Model ... end
112. MODULES job = User.new('Jano') job.persist
113. ADD BEHAVIOR TO CLASSES
114. MODULES module Findable def find_by_id(id) ... end end
115. MODULES class User extends Findable ... end
116. MODULES user = User.find_by_id(3)
117. METAPROGRAMMING
118. (USE WITH CAUTION)
119. (AKA THE EVAL IS EVIL RULE)
120. ACCESSORS
121. ACCESSORS class User attr_reader :name attr_reader :status end
122. OPEN CLASSES
123. OPEN CLASSES class Range def even select(&:even?) end end (0..10).even # => [2, 4, 6, 8, 10]
124. OPEN CLASSES class BuggyClass def buggy_method # the fix ... end end
125. OPEN CLASSES class Job alias_method :old_execute, :execute def execute ... old_execute end end
126. DEFINE METHODS
127. DEFINE METHODS obj = User.new User.class_eval do def represent ... end end obj.represent
128. DEFINE METHODS User.instance_eval do def random ... end end User.random
129. SINGLETON METHODS
130. SINGLETON METHOD obj = Person.new class << obj def represent ... end end obj.represent
131. (A LOT MORE TO EXPLORE...)
132. ONE LAST ADVICE
133. कഁ཭
134. SHU कഁ཭
135. HA कഁ཭
136. RI कഁ཭
138. CONCLUSIONS
139. EMBRACE DYNAMIC TYPING
140. BE MORE DECLARATIVE
141. WRITE LESS DO MORE
142. CONVENTIONS AND IDIOMS ARE NOT LAWS
143. THERE IS NO TRUE PATH
144. ENJOY RUBY! (AND JAVA TOO)
145. DANKESCHÖN!
146. ¡MUCHAS GRACIAS!
147. IMAGES • http://006.shanbara.jp/movie/data/fat1367385194099.jpg • http://wfiles.brothersoft.com/n/nirvana-desktop_157301-1600x1200.jpg • http://stilestili.com/wp-content/uploads/2013/04/Ryan- Gosling2-2048x2560.jpg • http://upload.wikimedia.org/wikipedia/commons/thumb/1/14/ James_Gosling_2008.jpg/1018px-James_Gosling_2008.jpg • http://www.flickr.com/photos/john_lam/1910968816/