Dissecting Ruby with Ruby

Dig into massive libraries with ease when you learn how to dissect ruby with ruby.

India Ruby Conf Edition.

Transcript

1. Dissecting Ruby with Ruby @schneems
2. @schneems
3. Schnauser
5. That man is married to Ruby, so to speak
6. Ruby Me
7. Python <3 ?
8. Hans Peter Von Wolfe (the 5th)
9. Sextant Gem
10. Wicked ‘ ‘ Gem
11. Triage Code codetriage.com
13. Adjunct Professor
14. Good News Everyone! schneems.com/ut-rails
16. We optimize developer happiness
17. Git Push: Deploy
18. Ruby Task Force
19. Ruby Task Force Member
20. Co-worker
21. Eat Naan Talk Ruby
22. Eat Naan Talk Ruby
23. Warning: I have Naan Jokes
24. Some of them fall a bit “flat”
25. Close your Laptops
26. Unless you’re commenting on rails/rails issues
27. We’ve all been there
28. That comment is no longer valid “
29. I have no Idea how it works, it just does. “
30. Docs? Just look at the source code “
31. Get in Get Info Get Around
32. Get in
33. $ bundle open wicked
34. $ bundle open wicked
35. Set Editor
36. ~/.bashrc export EDITOR="mvim"
37. ~/.bashrc export EDITOR="subl -w"
38. $ echo $EDITOR subl -w
39. Get Info Out
40. Forget Fancy Debuggers
41. All you need is “puts”
42. Tracer Round
43. puts “=================” Tracer Round
44. Find the output
45. puts “=================” Tracer Round
46. puts “=================” Tracer Round Do you see it?
47. How about now?
48. A note on Notation
49. String.new Class/Module
50. String.new Method
51. String.new class method
52. Kernel#puts Not class method
53. Caution!
54. Nil
55. Nil Null
56. Nil Null Naan
57. Obi-Naan Kenobi
58. Who uses Ruby 2.0?
59. Who uses Ruby 1.9.3?
60. Who uses Ruby 1.8.7?
61. Ruby 1.8.7 is End of Life-d in days
62. try 2.0.0 or JRuby on heroku
63. Get Around
64. Let’s look at Ruby
65. Where is this method used? Problem:
66. Solution: Kernel#caller
67. www. ruby-doc .org
68. Wat?
69. Kernel#caller gives you the back trace
70. def self.order_by_issue_count puts caller.inspect self.order("issues_count DESC") end
71. [ "~/projects/triage/app/controllers/pages_controller.rb:6:in `index'", "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/implicit_render.rb:4:in "ruby/gems/actionpack-3.2.12/lib/abstract_controller/base.rb:167:in `process_act "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rendering.rb:10:in `proc "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:18:in `block i "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:414:in `_run__37 "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405:in `__run_ca "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385:in `_run_pro "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:81:in `run_callb "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:17:in `process "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rescue.rb:29:in `proces "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:30:i "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `bloc "ruby/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `inst "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:29:i File
72. [ "~/projects/triage/app/controllers/pages_controller.rb:6:in `index'", "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/implicit_render.rb:4:in "ruby/gems/actionpack-3.2.12/lib/abstract_controller/base.rb:167:in `process_act "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rendering.rb:10:in `proc "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:18:in `block i "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:414:in `_run__37 "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405:in `__run_ca "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385:in `_run_pro "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:81:in `run_callb "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:17:in `process "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rescue.rb:29:in `proces "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:30:i "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `bloc "ruby/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `inst "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:29:i Line Number
73. [ "~/projects/triage/app/controllers/pages_controller.rb:6:in `index'", "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/implicit_render.rb:4:in "ruby/gems/actionpack-3.2.12/lib/abstract_controller/base.rb:167:in `process_act "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rendering.rb:10:in `proc "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:18:in `block i "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:414:in `_run__37 "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405:in `__run_ca "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385:in `_run_pro "ruby/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:81:in `run_callb "ruby/gems/actionpack-3.2.12/lib/abstract_controller/callbacks.rb:17:in `process "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/rescue.rb:29:in `proces "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:30:i "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `bloc "ruby/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb "ruby/gems/activesupport-3.2.12/lib/active_support/notifications.rb:123:in `inst "ruby/gems/actionpack-3.2.12/lib/action_controller/metal/instrumentation.rb:29:i Method Name
74. Use Kernel#caller
75. Where is this method defined? Problem:
76. Introducing My favorite super secret class
77. Method
78. Object#method
79. > m = "hello world".method(:upcase) => #<Method: String#upcase>
80. > m = "hello world".method(:upcase) => #<Method: String#upcase> > m.class => Method
81. > m = "hello world".method(:upcase) => #<Method: String#upcase> > m.class => Method > m.call => "HELLO WORLD"
82. Where is this method defined? Problem: (recap)
83. Solution: Method#source_location
84. $ cat app/models/user.rb class User < ActiveRecord::Base has_many :repo_subscriptions, dependent: :destroy has_many :repos, :through => :repo_subscriptions scope :public, where("private is not true") alias_attribute :token, :github_access_token def self.random order("RANDOM()") end #...
85. $ rails c User.last.method(:github_url).source_location
86. $ rails c User.last.method(:github_url).source_location =>["~/projects/triage/app/models/user.rb", 93]
87. $ rails c User.last.method(:github_url).source_location =>["~/projects/triage/app/models/user.rb", 93] File
88. $ rails c User.last.method(:github_url).source_location =>["~/projects/triage/app/models/user.rb", 93] Line Number
89. Let’s see something real
90. link_to in (rails) email templates needs a host set, but fails if you include http:// Problem:
91. Fails config.action_mailer.default_url_options = { host: 'http://example.com' } http://http://example.com
92. Works config.action_mailer.default_url_options = { host: 'example.com' } http://example.com
93. let’s remove the http:// automatically, but how? Problem:
94. How does that option get used?
95. <% puts method(:link_to).source_location %>
96. <% puts method(:link_to).source_location %> [“ruby/gems/actionpack-3.2.12/lib/action_view/helpers/ url_helper.rb” 231]
97. $ bundle open $ bundle open actionpack
98. def link_to(*args, &block) if block_given? options = args.first || {} html_options = args.second link_to(capture(&block), options, html_options) else name = args[0] options = args[1] || {} html_options = args[2] html_options = convert_options_to_data_attributes(options, html_options url = url_for(options) href = html_options['href'] tag_options = tag_options(html_options) href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" unless href "<a #{href_attr}#{tag_options}>#{ERB::Util.html_escape(name || url)}</a end end {
99. Enhance
100. name = args[0] options = args[1] || {} html_options = args[2] html_options = convert_options_to_data_attributes(opt url = url_for(options) href = html_options['href'] tag_options = tag_options(html_options) href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" "<a #{href_attr}#{tag_options}>#{ERB::Util.html_escap
101. name = args[0] options = args[1] || {} html_options = args[2] html_options = convert_options_to_data_attributes(opt url = url_for(options) href = html_options['href'] tag_options = tag_options(html_options) href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" "<a #{href_attr}#{tag_options}>#{ERB::Util.html_escap
102. name = args[0] options = args[1] || {} html_options = args[2] html_options = convert_options_to_data_attributes(opt url = url_for(options) href = html_options['href'] tag_options = tag_options(html_options) href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" "<a #{href_attr}#{tag_options}>#{ERB::Util.html_escap
103. Which url_for?
106. 13 matches 12 Files
107. Method# source_location to the rescue
108. name = args[0] options = args[1] || {} html_options = args[2] html_options = convert_options_to_data_attributes(opt puts “==============================” puts method(:url_for).source_location url = url_for(options) href = html_options['href'] tag_options = tag_options(html_options)
109. puts “==============================” puts method(:url_for).source_location => [“actionpack-3.2.12/ lib/ action_view/helpers/url_helper.rb”, 100]
110. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(: super when :back controller.request.env["HTTP_REFERER"] || 'javasc else polymorphic_path(options) end end
111. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(: puts "===========================" puts self.class.ancestors super when :back controller.request.env["HTTP_REFERER"] || 'javasc else polymorphic_path(options) end end
112. Module#ancestors
113. “foo”.class.ancestors => [String, Comparable, Object, Kernel, BasicObject]
114. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(: puts "===========================" puts self.class.ancestors super when :back controller.request.env["HTTP_REFERER"] || 'javasc else polymorphic_path(options) end end
115. puts "===========================" puts self.class.ancestors [#<Class:0x007f8d0bc26ad8>, #<Module:0x007f8d0d65aaa8 #<Module:0x007f8d0a33d4e0>, ActionMailer::MailHelper ActionDispatch::Routing::RouteSet::MountedHelpers, #<Module:0x007f8d0d6bcb90>, ActionDispatch::Routing: ActionView::Base, Devise::OmniAuth::UrlHelpers, Devi WillPaginate::ActionView, WillPaginate::ViewHelpers, ActionView::Helpers, ActionView::Helpers::Translatio ActionView::Helpers::RecordTagHelper, ActionControll ActionView::Helpers::OutputSafetyHelper, ActionView: ActionView::Helpers::JavaScriptHelper, ActionView::H ActionView::Helpers::FormHelper, ActionView::Helpers ActionView::Helpers::DebugHelper, ActionView::Helper ActionView::Helpers::ControllerHelper, ActionView::H ActionView::Helpers::AtomFeedHelper, ActionView::Hel
117. Too much Ruby?
118. Solution: Moar Ruby
119. Module#method_defined?
120. "foo".class.method_defined?(:upcase) => true Module#method_defined?
121. "foo".class.method_defined?(:upcase) => true 99.class.method_defined?(:upcase) => false Module#method_defined?
122. Module#instance_method
123. User.new.method(:github_url).source_location =>["~/projects/triage/app/models/user.rb", 93] User.instance_method(:github_url).source_location =>["~/projects/triage/app/models/user.rb", 93] Module#instance_method
124. What were we doing?
125. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(: puts "===========================" puts self.class.ancestors super when :back controller.request.env["HTTP_REFERER"] || 'javasc else polymorphic_path(options) end end
126. Right
127. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(:only puts "===========================" self.class.ancestors.each do |klass| next unless klass.method_defined?(:url_for) puts klass.instance_method(:url_for).source_locatio end super when :back controller.request.env["HTTP_REFERER"] || 'javascript else polymorphic_path(options)
128. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(:only puts "===========================" self.class.ancestors.each do |klass| next unless klass.method_defined?(:url_for) puts klass.instance_method(:url_for).source_locatio end super when :back controller.request.env["HTTP_REFERER"] || 'javascript else polymorphic_path(options)
129. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(:only puts "===========================" self.class.ancestors.each do |klass| next unless klass.method_defined?(:url_for) puts klass.instance_method(:url_for).source_locatio end super when :back controller.request.env["HTTP_REFERER"] || 'javascript else polymorphic_path(options)
130. def url_for(options = {}) options ||= {} case options when String options when Hash options = options.symbolize_keys.reverse_merge!(:only puts "===========================" self.class.ancestors.each do |klass| next unless klass.method_defined?(:url_for) puts klass.instance_method(:url_for).source_locatio end super when :back controller.request.env["HTTP_REFERER"] || 'javascript else polymorphic_path(options)
131. self.class.ancestors.each do |klass| next unless klass.method_defined?(:url_for) puts klass.instance_method(:url_for).source_location end ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143
132. ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143 One of these things is not like the others
133. ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143 Nope
134. ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143 Nope
135. ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143 Nope
136. ====================== actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_view/helpers/url_helper.rb 100 actionpack-3.2.12/lib/action_dispatch/routing/url_for.rb 143 Yeah!
137. Almost Done (kinda)
138. Quick Break:
141. Back to your regularly scheduled broadcast
142. Verify Caller def url_for(options = nil) puts "===========================" puts caller.inspect case options when String options when nil, Hash _routes.url_for((options || {}).symbolize_keys.rev else polymorphic_url(options) end end
143. It checks out ============================ [“actionpack-3.2.12/ lib/ action_view/ helpers/ url_helper.rb:112:in `url_for'", # ...
144. Follow the Source def url_for(options = nil) case options when String options when nil, Hash puts "===========================" puts _routes.method(:url_for).source_location _routes.url_for((options || {}).symbolize_keys.rev else polymorphic_url(options) end end
145. action_dispatch/routing/route_set.rb:572 def url_for(options) finalize! options = (options || {}).reverse_merge!(default_url_options) handle_positional_args(options) user, password = extract_authentication(options) path_segments = options.delete(:_path_segments) script_name = options.delete(:script_name) path = (script_name.blank? ? _generate_prefix(options) : script_name.chomp('/') path_options = options.except(*RESERVED_OPTIONS) path_options = yield(path_options) if block_given? path_addition, params = generate(path_options, path_segments || {}) path << path_addition params.merge!(options[:params] || {}) ActionDispatch::Http::URL.url_for(options.merge!({ :path => path, :params => params, :user => user, :password => password })) end
146. Success!
147. Now What???
148. Reproduce the problem
149. Attempt a fix
150. Raise Awareness (open an issue)
151. rails/ rails#9794