Forget about classes, welcome objects

This is a talk about how to fight complexity using OO forgotten concepts.

Transcript

1. Alexandre de Oliveira (@kurko) Forget about classes,
   welcome objects
4. Perspective
5. Alan Kay
6. “Point of view is worth 80 IQ points” - Alan Kay
8. VI
10. Reality as we conceive it
11. Source: http://2.bp.blogspot.com/_EussjcZFO-c/SW1ITAQSlRI/AAAAAAAAAZY/Zmn7X88qBHk/s400/Princess+Anne+says+hello.jpg
12. OOP?
13. “OOP to me means only messaging, local retention and protection and hiding of state” Alan Kay
17. Complexity http://dougbelshaw.com/presentations/2012/ILTA/assets/complexity.jpg
18. Problem #1: disorganisation
19. ONE BIG OBJECT™
20. many small objects collaborating with each other
21. http://20px.com/wp-content/uploads/2013/02/unicorn_pooping_a_rainbow_20px.jpg
22. such complexity, much wow
23. http://adeviantman.deviantart.com/art/Pink-Fluffy-Unicorns-Dancing-On-Rainbows-315632047
24. Problem #2: procedural code
25. Domain Organization Project Stories Members Importing projects from Pivotal Tracker
26. class ImportationService ! ! ! ! ! ! ! ! ! ! end
27. class ImportationService def process orgs = Organizations.new(client).import end end
28. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end ! ! ! end end
29. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end projects.each do |project| Members.new(client).import end end end
30. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end projects.each do |project| Members.new(client).import Stories.new(client).import end end end
31. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end projects.each do |project| Members.new(client).import Stories.new(client).import unless client.github? end end end
32. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end projects.each do |project| Members.new(client).import Stories.new(client).import unless client.github? end end end Beginning of the end
33. def process_extension!(extension_price, options={}) options.reverse_merge!({ :credit_card => user.default_credit_card, :billing_address => options[:credit_card].try(:billing_address) || user.default_address, :store => order.store, :tax => tax, :days => 14, :buyout => false }) ! creator = options[:creator] return process_extension_without_charge!(options) if options[:no_charge] ! response = Payment::Gateway.charge!( extension_price.cents.to_f/100, options[:credit_card].ext_cc_id, self.user.id, options[:store].try(:address).try(:country) ) ! # payment failed unless response[:ext_transaction_id].present? self.order.order_responses.create(:message => response[:error]) self.errors.add(:base, response[:error]) return false end ! data = { :ext_transaction_id => response[:ext_transaction_id], :parent_order_id => self.order.id, :parent_order_item_id => self.id, :ccauth_reply_authorization_code => response[:ccauth_reply_authorization_code] } ! if options[:buyout] # it's a buyout OrderTransaction.buyout!( self.order.currency, extension_price.cents - options[:tax].cents, self, data, creator ) ! OrderTransaction.tax_charged!( self.order.currency, options[:tax].cents, self, data, creator ) ! process_convert_to_purchase! ! else # it's a regular extension begin OrderTransaction.extension!( "#{options[:days]} days", self.order.currency, extension_price.cents - options[:tax].cents, self, data, creator ) OrderTransaction.tax_charged!( self.order.currency, options[:tax].cents, self, data, creator ) # Increment extension days for current Item self.increment(:extension_days, options[:days]) self.update_attribute(:state, 'shipped_with_customer_extended') OrderItemMailer.rental_extended(self).deliver rescue Net::SMTPSyntaxError => exception Airbrake.notify( :error_class => exception.class.to_s, :error_message => "Bad Email Address Format. Order Item: #{self.id}. Email: #{self.order.user.email}", :parameters => self.attributes, :backtrace => caller) end end ! return true end 100+ LoC Real Code™
34. Flattened Domain Organization Project Stories Members
35. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg Curiosity
36. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg 2.5 M LoC
37. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg Written in C
38. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg Completely OOP
39. WAT http://www.gazetadopovo.com.br/blogs/cinema-em-casa/wp-content/uploads/sites/30/2013/05/short2circuit2654.jpg
40. http://www.wired.com/wp-content/uploads/blogs/design/wp-content/uploads/2012/08/MSL-Rover-NX-CAD-model.jpg
41. Path Finder Radio receiver Sample Analysis Descent Imager ChemCam UV Sensor Engine Wheels
42. Component 1 Component 2 Component 3 Component n Message Queue Component 4 Component 5 Component 6 Component z
43. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg • Lots of messages • No mutexes, no transactional memory • Complete isolation between modules
44. OOP is not about Objects http://3.bp.blogspot.com/-MwiEp-63Qro/TrQvxNtQbBI/AAAAAAAABNc/6c8bAI0kdAM/s1600/facteur.jpg
45. It’s about the Message.
46. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg Objects: what the system is. Messages: what the system does.
47. http://x4.fjcdn.com/comments/Oh+_a70c957887dd1e4f713fb14db1dc582a.jpg Likely built with OOP
48. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg NASA basically rewrote Erlang
49. http://cdn.cantechletter.com/wp-content/uploads/2012/09/NASA-Mars-Rover.jpg "Erlang might be the only object oriented language” - Joe Armstrong
50. Person calls Pencil#write 1/2 Developer’s point of view Person Pencil Pen
51. 2/2 Object’s point of view someone someone else pay() pay() someone else
54. Objects = 2 Complexity = 1
55. Objects = 3 Complexity = 3
56. Objects = 6 Complexity = ?
57. Objects = 6 Complexity = 15
58. How to stop complexity
59. How to stop wasting time complexity
60. How to stop wasting money wasting time complexity
61. “The key to scalability lies in how messaging is actually done. The key to abstraction and compactness lies in a felicitous combination of design and mathematics." ! - Alan Kay
62. Constructal Law
63. http://upload.wikimedia.org/wikipedia/commons/f/f6/Bright_green_tree_-_Waikato.jpg
64. http://hqwallpapersplus.com/wp-content/uploads/2013/09/Snowflake-Pictures-11.jpg
65. http://readywisconsin.wi.gov/lightning/images/Lightning_1.jpg
66. http://marjorymejia.com/wp-content/uploads/2012/10/800px-Mouths_of_amazon_geocover_1990.png
67. http://lh3.ggpht.com/-MgYN_UYAeCQ/S3xhh3CvNlI/AAAAAAAAAIU/j9rFK8ew7cE/900898-Resin%2520cast%2520human%2520lungs%2520and%2520bronchial%2520tree.jpg
68. http://www.spatialcomplexity.info/files/2012/12/morphology-map.png
69. Objects = 6 Complexity = 15
70. Objects = 7 Complexity = 8
71. C O Before After Architecture comparison
72. Example Module Module Module Computer Computer Computer
73. Danger, Will Robinson! Módulo Módulo Módulo A B
74. Effects ! 1. decreased complexity 2. simpler code 3. lower cognitive load 4. less wasted $$$
75. class ImportationService def process orgs = Organizations.new(client).import orgs.each do |org| projects = Projects.new(org).import end projects.each do |project| Members.new(client).import Stories.new(client).import end end end Before
76. module RemoteService class Organizations def initialize(remote_client) @client = remote_client end def import import_organizations Projects.new(@client).import end ! private ! def import_organizations organizations = @client.organizations OrganizationsTable.new(organizations).save end end end After
77. module RemoteService class Projects def initialize(remote_client) @client = remote_client end def import import_projects Members.new(@client).import Stories.new(@client).import end ! private ! def import_projects projects = @client.projects ProjectsTable.new(projects).save end end end
78. module RemoteService class Projects def initialize(remote_client) @client = remote_client end def import import_projects Members.new(@client).import Stories.new(@client).import unless @client.github? end ! private ! def import_projects projects = @client.projects ProjectsTable.new(projects).save end end end What now?
79. module PivotalTracker class Client def organizations HTTParty.get(‘url’).map { |i| Response::Organization.new(i) } end ! def projects HTTParty.get(‘url2’).map { |i| Response::Project.new(i) } end ! def members HTTParty.get(‘url3’).map { |i| Response::Member.new(i) } end ! def stories HTTParty.get(‘url4’).map { |i| Response::Story.new(i) } end end end
80. module Github class Client def organizations HTTParty.get(‘url’).map { |i| Response::Organization.new(i) } end ! ! ! ! ! ! ! ! ! ! ! ! end end
81. module Github class Client def organizations HTTParty.get(‘url’).map { |i| Response::Organization.new(i) } end ! def projects HTTParty.get(‘url2’).map { |i| Response::Project.new(i) } end ! ! ! ! ! ! ! ! end end
82. module Github class Client def organizations HTTParty.get(‘url’).map { |i| Response::Organization.new(i) } end ! def projects HTTParty.get(‘url2’).map { |i| Response::Project.new(i) } end ! def members HTTParty.get(‘url3’).map { |i| Response::Member.new(i) } end ! ! ! ! end end
83. module Github class Client def organizations HTTParty.get(‘url’).map { |i| Response::Organization.new(i) } end ! def projects HTTParty.get(‘url2’).map { |i| Response::Project.new(i) } end ! def members HTTParty.get(‘url3’).map { |i| Response::Member.new(i) } end ! def stories [] end end end
84. Effects ! 1. flexible code 2. less changes 3. Open/Closed principle 4. less wasted $$$
85. What about debugging?
86. What about debugging? Module Module Module Computer Computer Computer
87. Binary Search Module Module Module Computer Computer Computer
88. Binary Search Module Module Computer Computer Computer has the bug
89. Instrumentation Module Computer Tests
90. Write great code
91. Embrace OO
92. “It (OOP) can be done in Smalltalk and in LISP” Alan Kay
93. Thank you!
94. Resources • http://computinged.wordpress.com/2010/09/15/alan-kay-on-motis-objects-ever-cacm-article/ • http://jlouisramblings.blogspot.com/2012/08/getting-25-megalines-of-code-to-behave.html