That's Not Very Ruby of You

Keynote on final day of RubyConf 2013.

How Ruby is your Ruby? As we've found our way to Ruby, we've all brought with us habits and idioms from the languages we know and love (or hate). Sometimes, these habits serve us well, and other times, they make our lives more difficult. More often, they make life difficult for our collaborators, who don't expect to see C, Java, or PHP in their Ruby codebase.

Not only that, as many new Rubyists have found their way to Ruby from Rails, they've brought along various Rails-isms, some of which aren't even a good idea in Rails-land (callbacks, anyone?), or dependencies on libraries like ActiveSupport which are overkill for their real needs.

We'll talk about some of the baggage we bring to our Ruby code, and some simple techniques that will help us leave it behind.

Transcript

1. That’s Not Very Ruby of You @erniemiller http://erniemiller.org
3. Ask me about
5. Keynote
7. C# (554.37 Hz)
8. C# (554.37 Hz)
9. What is Ruby?
10. #include <stdio.h> ! int main() { int a = -1; int b = -1; int c = -1; ! while (a != 0 || b != 0) { printf("Enter two numbers (0 0 to quit): "); scanf("%d%d", &a, &b); ! c = a + b; ! printf("The sum of the numbers you entered is %d\n", c); } }
11. def int(*) end ! def main yield end ! int main() { int a = -1; int b = -1; int c = -1; ! while (a != 0 || b != 0) printf("Enter two numbers (0 0 to quit): "); a, b = scanf("%d%d"); ! c = a + b; ! printf("The sum of the numbers you entered is %d\n", c); end }
12. require 'scanf' ! def int(*) end ! def main yield end ! int main() { int a = -1; int b = -1; int c = -1; ! while (a != 0 || b != 0) printf("Enter two numbers (0 0 to quit): "); a, b = scanf("%d%d"); ! c = a + b; ! printf("The sum of the numbers you entered is %d\n", c); end } Enter two numbers (0 0 to quit): 2 4 The sum of the numbers you entered is 6 Enter two numbers (0 0 to quit): 1 2 The sum of the numbers you entered is 3 Enter two numbers (0 0 to quit): 0 0 The sum of the numbers you entered is 0
13. require 'scanf' ! def int(*) end ! def main yield end ! int main() { int a = -1; int b = -1; int c = -1; ! while (a != 0 || b != 0) printf("Enter two numbers (0 0 to quit): "); a, b = scanf("%d%d"); ! c = a + b; ! printf("The sum of the numbers you entered is %d\n", c); end } Enter two numbers (0 0 to quit): 2 4 The sum of the numbers you entered is 6 Enter two numbers (0 0 to quit): 1 2 The sum of the numbers you entered is 3 Enter two numbers (0 0 to quit): 0 0 The sum of the numbers you entered is 0
14. require 'scanf' ! def int(*) end ! def main yield end ! int main() { int a = -1; int b = -1; int c = -1; ! while (a != 0 || b != 0) printf("Enter two numbers (0 0 to quit): "); a, b = scanf("%d%d"); ! c = a + b; ! printf("The sum of the numbers you entered is %d\n", c); end } Enter two numbers (0 0 to quit): 2 4 The sum of the numbers you entered is 6 Enter two numbers (0 0 to quit): 1 2 The sum of the numbers you entered is 3 Enter two numbers (0 0 to quit): 0 0 The sum of the numbers you entered is 0
15. <? $fruits = array('banana', 'apple', 'orange') ?> A sorted list of fruits: ! <? sort($fruits) ?> <? foreach ($fruits as $fruit) { ?> * <?= $fruit ?> ! <? } ?> ! <?= $fruits[0] ?> is spelled: <?= implode(' ', str_split($fruits[0])) ?> <? $rubies = array( '1.8' => 'unsupported', '1.9' => 'supported', '2.0' => 'supported' ) ?> ! ! Important note regarding Ruby versions: ! <? foreach ($rubies as $ruby => $status) { ?> * <?= implode(' is ', array($ruby, $status)) ?> ! <? } ?>
16. PersonalHomePage.new.render(DATA.read) ! __END__ <% $fruits = array('banana', 'apple', 'orange') %> A sorted list of fruits: ! <% sort($fruits) %> <% for $fruit in $fruits %> * <%= $fruit %> <% end %> ! <%= $fruits[0] %> is spelled: <%= implode(' ', str_split($fruits[0])) %> <% $rubies = array( '1.8' => 'unsupported', '1.9' => 'supported', '2.0' => 'supported' ) %> Important note regarding Ruby versions: ! <% for ($ruby, $status) in $rubies %> * <%= implode(' is ', array($ruby, $status)) %> <% end %>
17. require 'erb' ! class PersonalHomePage def array(*args) Hash === args.first ? args.first : Array(args) end ! def implode(*args) array_join(*args.reverse) end ! Array.instance_methods.each do |method_name| define_method "array_#{method_name}", ->(array, *args, &block) { array.to_a.send(method_name, *args, &block) } end ! String.instance_methods.each do |method_name| define_method "str_#{method_name}", ->(string, *args, &block) { string.send(method_name, *args, &block) } end ! alias sort array_sort! ! def str_split(string, length = 1) string.scan(/.{1,#{length}}/) end ! def render(template) ERB.new(template, nil, '<>').run(binding) end end ! PersonalHomePage.new.render(DATA.read)
18. require 'erb' ! class PersonalHomePage def array(*args) Hash === args.first ? args.first : Array(args) end ! def implode(*args) array_join(*args.reverse) end ! Array.instance_methods.each do |method_name| define_method "array_#{method_name}", ->(array, *args, &block) { array.to_a.send(method_name, *args, &block) } end ! String.instance_methods.each do |method_name| define_method "str_#{method_name}", ->(string, *args, &block) { string.send(method_name, *args, &block) } end ! alias sort array_sort! ! def str_split(string, length = 1) string.scan(/.{1,#{length}}/) end ! def render(template) ERB.new(template, nil, '<>').run(binding) end end ! PersonalHomePage.new.render(DATA.read)
19. A sorted list of fruits: ! * apple * banana * orange ! apple is spelled: a p p l e ! Important note regarding Ruby versions: ! * 1.8 is unsupported * 1.9 is supported * 2.0 is supported
20. App = { say: function(string) { console.log(string) }, ifMultipleOf: function(number, check, callback) { (check % number) == 0 ? callback(check) : nil; }, ifEven: function(number, callback) { App.ifMultipleOf(2, number, callback); }, proclaimEvenness: function(number) { App.say("It would appear that "+number+" is an even number."); } } App.say("Hello, world!"); App.ifEven(42, App['proclaimEvenness']);
21. ! ! ! ! ! ! ! App = { say: ->(string) { console.log(string) }, ifMultipleOf: ->(number, check, callback) { (check % number) == 0 ? callback.(check) : nil; }, ifEven: ->(number, callback) { App.ifMultipleOf(2, number, callback); }, proclaimEvenness: ->(number) { App.say("It would appear that "+number+" is an even number."); } } App.say("Hello, world!"); App.ifEven(42, App['proclaimEvenness']);
22. class Hash def method_missing(method_id, *args, &block) has_key?(method_id) ? self[method_id].(*args, &block) : super end ! def [](key) fetch(key) { fetch(key.to_sym) } # LOL GC end ! def respond_to_missing?(method_id, include_private = false) has_key?(method_id) || super end end ! class Fixnum alias to_str to_s end ! class Console def log(*args) puts *args end end ! console = Console.new ! Hello, world! It would appear that 42 is an even number.
23. class Hash def method_missing(method_id, *args, &block) has_key?(method_id) ? self[method_id].(*args, &block) : super end ! def [](key) fetch(key) { fetch(key.to_sym) } # LOL GC end ! def respond_to_missing?(method_id, include_private = false) has_key?(method_id) || super end end ! class Fixnum alias to_str to_s end ! class Console def log(*args) puts *args end end ! console = Console.new ! Hello, world! It would appear that 42 is an even number.
24. class Person: def __init__(self, name, age): self.name = name self.age = age ! person = Person('Ernie', 36) ! print person.name print person.age person.nonexistent_attribute = 'Seriously?' print person.nonexistent_attribute
25. ! ! ! ! class Person def __init__(se1f, name, age) se1f.name = name se1f.age = age end end ! person = Person('Ernie', 36) ! print person.name print person.age person.nonexistent_attribute = 'Seriously?' print person.nonexistent_attribute
26. class Object alias print puts ! def setter_block(name) ->(*args) { instance_variable_get(:@__attributes__)[name] = *args } end ! def getter_block(name) ->(*args) { instance_variable_get(:@__attributes__)[name] } end ! def method_missing(method_id, *args, &block) method_name = method_id.to_s if method_name.end_with?('=') && self.instance_variable_defined?(:@__attributes__) attribute_name = method_name.chop define_singleton_method(method_name, setter_block(attribute_name)) define_singleton_method(attribute_name, getter_block(attribute_name)) send(method_name, *args, &block) elsif Object.const_defined?(method_id) obj = Object.const_get(method_id).allocate obj.instance_variable_set(:@__attributes__, {}) obj.__init__(obj, *args, &block) obj else super end rescue NameError => e super end end Ernie 36 Seriously?
27. WxxÑ g{Éâz{àá If your code has a syntax error, does it stop being Ruby?
28. Interpreter
29. Interpreter
30. People
31. Happiness
32. Ruby is a language
33. Ruby is a storytelling tool
34. We Are Storytellers
37. def edit_distance length1, length2 = @string1.length, @string2.length # puts "length1: #{length1} length2: #{length2}" # row = [nil] * length1 # prev_row = row prev_row = row = (0..length1).to_a (1..length2).each do |y| # puts "prev_row: #{prev_row.inspect}" row = [y] * (length1 + 1) # (1..length1).each do |column| (1..length1).each do |x| # if @string1[x - 1] == @string2[y - 1] # row[column] = prev_row[column - 1] # else row[x] = if @string1[x - 1] == @string2[y - 1] prev_row[x - 1] else # row[column] = find_min(row, prev_row, column) [ row[x - 1] + 1, # delete? prev_row[x] + 1, # insert? prev_row[x - 1] + 1 # substitute? ].min end end # puts "row: #{row.inspect}" prev_row = row end row.last end
38. def edit_distance length1, length2 = @string1.length, @string2.length # puts "length1: #{length1} length2: #{length2}" # row = [nil] * length1 # prev_row = row prev_row = row = (0..length1).to_a (1..length2).each do |y| # puts "prev_row: #{prev_row.inspect}" row = [y] * (length1 + 1) # (1..length1).each do |column| (1..length1).each do |x| # if @string1[x - 1] == @string2[y - 1] # row[column] = prev_row[column - 1] # else row[x] = if @string1[x - 1] == @string2[y - 1] prev_row[x - 1] else # row[column] = find_min(row, prev_row, column) [ row[x - 1] + 1, # delete? prev_row[x] + 1, # insert? prev_row[x - 1] + 1 # substitute? ].min end end # puts "row: #{row.inspect}" prev_row = row end row.last end
39. class City def initialize @traits = [] end ! def trait description @traits << description end ! def space needle "for knitting space socks." end ! def grunge music "smells like teen spirit" end ! def emerald city, usa trait space :needle trait grunge :music end end
40. class City def initialize @traits = [] end ! def trait description @traits << description end ! def space needle "for knitting space socks." end ! def grunge music "smells like teen spirit" end ! def emerald city, usa trait space :needle trait grunge :music end end
41. Before we proceed…
42. class Greeter def initialize ( greeting ) @greeting = greeting end def greet ( name, number_of_greetings = 1 ) number_of_greetings.times do puts ("#{ @greeting }, #{ name }!") end end end
43. class Greeter ! def initialize(greeting) @greeting = greeting end ! def greet(name, number_of_greetings = 1) number_of_greetings.times do puts "#{@greeting}, #{name}!" end end ! end
44. Soft tabs. Two spaces. Vertical space is free! All day, every day.
45. class Greeter ! # Initialize with a greeting, x. def initialize(x) @x = x end ! # Greet the person/group named x, # i times. def greet(x, i = 1) i.times { puts "#{@x}, #{x}!" } end ! end
46. If it’s not self-explanatory, it’s definitely not “X”. Unless you’re modeling a treasure map, or tic-tac-toe.
47. class Greeter ! def initialize(the_greeting_or_prefix) @the_greeting_or_prefix = the_greeting_or_prefix end ! def greet(name_of_person_to_greet, number_of_times_to_greet = 1) number_of_times_to_greet.times do puts “#{@the_greeting_or_prefix}, #{name_of_person_to_greet}!” end end ! end
48. class Greeter ! def initialize(the_greeting_or_prefix) @the_greeting_or_prefix = the_greeting_or_prefix end ! def greet(name_of_person_to_greet, number_of_times_to_greet = 1) number_of_times_to_greet.times do puts “#{@the_greeting_or_prefix}, #{name_of_person_to_greet}!” end end ! end
49. class Greeter ! def initialize(the_greeting_or_prefix) @the_greeting_or_prefix = the_greeting_or_prefix end ! def greet(name_of_person_to_greet, number_of_times_to_greet = 1) number_of_times_to_greet.times do puts “#{@the_greeting_or_prefix}, #{name_of_person_to_greet}!” end end ! end
50. You are very original. And you should be very proud of yourself.
51. class AwesomeGreeter ! def initialize(theSalutation) @theSalutation = theSalutation end ! def greetPersonOrGroup(nameOfGreetable, numberOfTimesToGreet = 1) numberOfTimesToGreet.times do puts("#{@theSalutation}, #{nameOfGreetable}!") end end ! end
53. Ruby is not Java. This is what we call in the industry a “feature.” Also: http://tinyurl.com/camelCase
54. class Word ! def similarity_to(other_word) score = normalized_distance(self, other_word) score += 100 if synonyms.include?(other_word) return score end ! end
55. class Word ! def similarity_to(other_word) score = normalized_distance(self, other_word) score += 100 if synonyms.include?(other_word) score end ! end
56. class Word ! def similarity_to(other_word) return 100 if synonyms.include?(other_word) normalized_distance(self, other_word) end ! end
57. return Everything is backward. It’ll be okay.
59. class Iffy ! def iffy if thing_is_true? do_some_stuff if other_thing_is_true? do_some_more_stuff if truthiness_is_everywhere do_the_stuffiest_stuff_ever unless just_kidding? end else do_some_different_stuff end else do_a_fallback_thing end end ! end
60. class Iffy ! def iffy if thing_is_true? do_some_stuff if other_thing_is_true? do_some_more_stuff if truthiness_is_everywhere do_the_stuffiest_stuff_ever unless just_kidding? end else do_some_different_stuff end else do_a_fallback_thing end end ! end
61. class Iffy ! def iffy if thing_is_true? do_some_stuff if other_thing_is_true? do_some_more_stuff if truthiness_is_everywhere do_the_stuffiest_stuff_ever unless just_kidding? end else do_some_different_stuff end else do_a_fallback_thing end end ! end
62. class Iffy ! def iffy if thing_is_true? do_some_stuff if other_thing_is_true? do_some_more_stuff if truthiness_is_everywhere do_the_stuffiest_stuff_ever unless just_kidding? end else do_some_different_stuff end else do_a_fallback_thing end end ! end
63. YOU CAN NOT HAS BUCKET OF LOGIC
64. 80-column lines An early warning system for complexity.
65. 80-column lines An early warning system for complexity.
66. module Util module_function ! def dashify(string) string.scan(/./).join('-') end ! def array_of_strings?(o) o.is_a?(Array) && o.all? { |obj| obj.is_a?(String) } end ! def array_of_arrays?(o) o.is_a?(Array) && o.all? { |obj| obj.is_a?(Array) } end ! def array_of_dates?(o) o.is_a?(Array) && o.all? { |obj| obj.respond_to?(:to_time) } end ! end
67. YOU CAN NOT HAS BUCKET OF METHODS
68. YOU CAN NOT HAS BUCKET OF METHODS if Class < Module puts 'That goes for you too, Class.' end
69. def initialize(attributes = {}) @attributes = attributes end
70. def initialize(attributes = {}) @attributes = typecast(attributes) end
71. YOU CAN NOT HAS BUCKET OF DATA
72. def initialize(attributes = {}) @attributes = Attributes.new(attributes) end
73. class InstallationsController < ActionController::Base ! def schedule desired_date = params[:desired_date] if request.xhr? begin if @installation.pending_credit_check? render :json => {:errors => ["Cannot schedule installation while credit check is pending"]}, :status => 400 return end audit_trail_for(current_user) do if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city) if @installation.scheduled_date date = @installation.scheduled_date.in_time_zone(@installation.city.timezone).to_date render :json => {:errors => nil, :html => schedule_response(@installation, date)} end else render :json => {:errors => [%Q{Could not update installation. #{@installation.errors.full_messages.join(' ')}}] } end end rescue ActiveRecord::RecordInvalid => e render :json => {:errors => [e.message] } rescue ArgumentError => e render :json => {:errors => ["Could not schedule installation. Start by making sure the desired date is on a business day."]} end else if @installation.pending_credit_check? flash[:error] = "Cannot schedule installation while credit check is pending" redirect_to installations_path(:city_id => @installation.city_id, :view => "calendar") and return end begin audit_trail_for(current_user) do if @installation.schedule!(desired_date, :installation_type => params[:installation_type], :city => @city) if @installation.scheduled_date if @installation.customer_provided_equipment? flash[:success] = %Q{Installation scheduled} else flash[:success] = %Q{Installation scheduled! Don't forget to order the equipment also.} end end else flash[:error] = %Q{Could not schedule installation, check the phase of the moon} end end rescue => e flash[:error] = e.message end redirect_to(@installation.customer_provided_equipment? ? customer_provided_installations_path : installations_path(:city_id => @installation.city_id, :view => "calendar")) end end ! end
74. class InstallationsController < ActionController::Base ! def schedule ScheduleInstallation.new(schedule_responder).call end ! private ! def schedule_responder if request.xhr? AJAXResponder.new(self) else HTMLResponder.new(self) end end ! end
76. ETOOMANYOBJECTS
77. -Oriented Object Programming
78. -Oriented Awesome Programming
82. escriptive D
83. escriptive Pr
86. Naming Things
88. We Are Storytellers
89. Name your characters.
90. Name their! actions.
91. Asha Yara
93. “ Vigorous writing is concise
94. “ Vigorous writing is concise.
95. “ A sentence should contain no unnecessary words, a paragraph no unnecessary sentences,
96. “ for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts.
97. “ This requires not that the writer make all sentences short or avoid all detail and treat subjects only in outline, but that every word tell.
98. HAPPINESS Expressiveness! + Power
100. WITH GREAT POWER COMES
101. WITH GREAT POWER COMES GREAT RESPONSIBILITY
103. = Expressiveness English
104. Expressiveness ≠ English
105. array = %w(first second third fourth fifth) ! array.first # => "first" array.last # => "fifth"
106. class Array ! def second self[1] end ! def third self[2] end ! def fourth self[3] end ! def fifth self[4] end ! def forty_two self[41] end ! end
107. class Array ! def second self[1] end ! def third self[2] end ! def fourth self[3] end ! def fifth self[4] end ! def forty_two self[41] end ! end array = %w(first second third fourth fifth) ! array.second # => "second" array.fourth # => "fourth"
108. class Array ! def second self[1] end ! def third self[2] end ! def fourth self[3] end ! def fifth self[4] end ! def forty_two self[41] end ! end array = %w(first second third fourth fifth) ! array.second # => "second" array.fourth # => "fourth" class Array ! def penultimate # EXPRESSIVE self[-2] end ! def antepenultimate # ZOMG SO EXPRESSIVE self[-3] end ! end
109. class Array ! def second self[1] end ! def third self[2] end ! def fourth self[3] end ! def fifth self[4] end ! def forty_two self[41] end ! end array = %w(first second third fourth fifth) ! array.second # => "second" array.fourth # => "fourth" class Array ! def penultimate # EXPRESSIVE self[-2] end ! def antepenultimate # ZOMG SO EXPRESSIVE self[-3] end ! end array.penultimate # => "fourth" array.antepenultimate # => "third"
110. class Array ! def second self[1] end ! def third self[2] end ! def fourth self[3] end ! def fifth self[4] end ! def forty_two self[41] end ! end array = %w(first second third fourth fifth) ! array.second # => "second" array.fourth # => "fourth" class Array ! def penultimate # EXPRESSIVE self[-2] end ! def antepenultimate # ZOMG SO EXPRESSIVE self[-3] end ! end array.penultimate # => "fourth" array.antepenultimate # => "third"
111. array = %w(first second third fourth fifth) ! array.include?('second') # => true
112. class Object ! def in?(container) container.include? self end ! end
113. class Object ! def in?(container) container.include? self end ! end array = %w(first second third fourth fifth) ! 'second'.in? array # => true
115. Before you monkey patch…
116. Does it address a real problem? * not a monkey
117. Does it follow OO! principles? * still not a monkey
118. Metaprogramming: It makes boring problems interesting.™ Class Macros
120. attr_reader :name, :age attr_writer :height, :weight attr_accessor :motto, :favorite_food
121. attr_reader :name, :age attr_writer :height, :weight attr_accessor :motto, :favorite_food
122. has_many :posts, :inverse_of => :user
123. has_many :posts, :inverse_of => :user
124. has_many :posts, :inverse_of => :user
125. has_many :posts, -> { order(:created_at => :desc) }, :inverse_of => :user, :class_name => 'Article', :foreign_key => 'person_id', :validate => false, :autosave => true, :dependent => :destroy do def method_in_an_anonymous_module_because_we_certainly_wont_regret_this puts 'LOL LSP!' end end
126. has_many :posts, -> { order(:created_at => :desc) }, :inverse_of => :user, :class_name => 'Article', :foreign_key => 'person_id', :validate => false, :autosave => true, :dependent => :destroy do def method_in_an_anonymous_module_because_we_certainly_wont_regret_this puts 'LOL LSP!' end end
127. class Cat delegate :work, :to => :owner, :prefix => 'servant', :allow_nil => true end
128. class Cat delegate :work, :to => :owner, :prefix => 'servant', :allow_nil => true end
129. class Cat delegate :work, :to => :owner, :prefix => 'servant', :allow_nil => true end
130. class Cat delegate :work, :to => :owner, :prefix => 'servant', :allow_nil => true end
131. def delegate(*methods) options = methods.pop unless options.is_a?(Hash) && to = options[:to] raise ArgumentError, 'Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter).' end ! prefix, allow_nil = options.values_at(:prefix, :allow_nil) ! if prefix == true && to =~ /^[^a-z_]/ raise ArgumentError, 'Can only automatically set the delegation prefix when delegating to a method.' end ! method_prefix = \ if prefix "#{prefix == true ? to : prefix}_" else '' end ! file, line = caller.first.split(':', 2) line = line.to_i ! to = to.to_s to = 'self.class' if to == 'class' ! methods.each do |method| definition = (method =~ /[^\]]=$/) ? 'arg' : '*args, &block' ! if allow_nil module_eval(<<-EOS, file, line - 3) def #{method_prefix}#{method}(#{definition}) _ = #{to} if !_.nil? || nil.respond_to?(:#{method}) _.#{method}(#{definition}) end end EOS else exception = %(raise "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}") ! module_eval(<<-EOS, file, line - 2) def #{method_prefix}#{method}(#{definition}) _ = #{to} _.#{method}(#{definition}) rescue NoMethodError if _.nil? #{exception} else raise end end EOS end end end
132. def delegate(*methods) options = methods.pop unless options.is_a?(Hash) && to = options[:to] raise ArgumentError, 'Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, to: :greeter).' end ! prefix, allow_nil = options.values_at(:prefix, :allow_nil) ! if prefix == true && to =~ /^[^a-z_]/ raise ArgumentError, 'Can only automatically set the delegation prefix when delegating to a method.' end ! method_prefix = \ if prefix "#{prefix == true ? to : prefix}_" else '' end ! file, line = caller.first.split(':', 2) line = line.to_i ! to = to.to_s to = 'self.class' if to == 'class' ! methods.each do |method| definition = (method =~ /[^\]]=$/) ? 'arg' : '*args, &block' ! if allow_nil module_eval(<<-EOS, file, line - 3) def #{method_prefix}#{method}(#{definition}) _ = #{to} if !_.nil? || nil.respond_to?(:#{method}) _.#{method}(#{definition}) end end EOS else exception = %(raise "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}") ! module_eval(<<-EOS, file, line - 2) def #{method_prefix}#{method}(#{definition}) _ = #{to} _.#{method}(#{definition}) rescue NoMethodError if _.nil? #{exception} else raise end end EOS end end end
133. class Module private ! def delegate(*args) dest, prefix = _extract_valid_delegation_options(args.pop) _define_delegators(caller_locations.first, prefix, dest, args) end ! def delegate_maybe(*args) dest, prefix = _extract_valid_delegation_options(args.pop) _define_delegators( caller_locations.first, prefix, "(_ = #{dest}; _.nil? ? NilDelegate.new : _)", args ) end ! def _define_delegators(from, prefix, accessor, args) args.each do |arg| method_name = [prefix, arg].compact.join('_') module_eval( _delegator(accessor, arg, method_name), from.path, from.lineno - 2 ) end end ! def _delegator(accessor, destination_method, local_method) %{ def #{local_method}(*args, &block) #{accessor}.__send__(:#{destination_method}, *args, &block) end } end ! def _extract_valid_delegation_options(opts) if Hash === opts && opts.has_key?(:to) [opts[:to].to_s.sub(/^([a-z])/, 'self.\1'), opts[:prefix]] else raise ArgumentError, 'Invalid delegation options. Delegate with :to.' end end end
134. class Module private ! def delegate(*args) dest, prefix = _extract_valid_delegation_options(args.pop) _define_delegators(caller_locations.first, prefix, dest, args) end ! def delegate_maybe(*args) dest, prefix = _extract_valid_delegation_options(args.pop) _define_delegators( caller_locations.first, prefix, "(_ = #{dest}; _.nil? ? NilDelegate.new : _)", args ) end ! def _define_delegators(from, prefix, accessor, args) args.each do |arg| method_name = [prefix, arg].compact.join('_') module_eval( _delegator(accessor, arg, method_name), from.path, from.lineno - 2 ) end end ! def _delegator(accessor, destination_method, local_method) %{ def #{local_method}(*args, &block) #{accessor}.__send__(:#{destination_method}, *args, &block) end } end ! def _extract_valid_delegation_options(opts) if Hash === opts && opts.has_key?(:to) [opts[:to].to_s.sub(/^([a-z])/, 'self.\1'), opts[:prefix]] else raise ArgumentError, 'Invalid delegation options. Delegate with :to.' end end end
135. class NilDelegate < BasicObject delegate *(nil.methods - [:__send__, :object_id]), :to => :__nil__ ! private ! def __nil__ nil end ! def method_missing(method_id, *args, &block) nil end ! def respond_to_missing?(method_id, include_private = false) true end end
136. # No options needed! YAY SIMPLICITY! has_some_awesome_feature
137. # No options needed! YAY SIMPLICITY! has_some_awesome_feature
138. extend MyAwesomeFeature include MyAwesomeFeature
139. extend MyAwesomeFeature include MyAwesomeFeature
140. EVERYBODY LOVES RULES!
141. What, not how 1
142. Idempotent 2
143. Order! Independent 3
144. Straightforward 4
145. Free of! Branching 5
146. Rules for Class Macros What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5
147. Rules for Class Macros What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5
148. Rules for Class Macros What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5
149. You have to know the rules in order to break them. Otherwise, it’s no fun.
150. Happiness
151. Surprises
154. Callbacks You didn’t really think I would leave these out?
157. class Base
158. require 'active_support/callbacks' ! class Base ! include ActiveSupport::Callbacks ! define_callbacks :auto_arming ! set_callback :auto_arming, :before do @weapons_armed = true end ! def fire_lasers run_callbacks :auto_arming do puts 'PEW PEW PEW!' if @weapons_armed end end ! end ! base = Base.new base.fire_lasers # => PEW PEW PEW!
159. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules Callbacks Not consistently. No. Nope. LOL!! Honorary tree.
160. class Base ! include ActiveSupport::Callbacks ! define_callbacks :auto_arming ! set_callback :auto_arming, :before, :arm_weapons, :if => :not_armed?, :unless => :training_mode? ! # ... ! def fire_lasers run_callbacks :auto_arming do puts 'PEW PEW PEW!' if @weapons_armed end end ! end
161. class Base ! include ActiveSupport::Callbacks ! define_callbacks :auto_arming ! set_callback :auto_arming, :before, :arm_weapons, :if => :not_armed?, :unless => :training_mode? ! # ... ! def fire_lasers run_callbacks :auto_arming do puts 'PEW PEW PEW!' if @weapons_armed end end ! end
162. class SecretBase < Base ! # This base shouldn't go making loud PEW PEW PEW noises # unless it really, really needs to. skip_callback :auto_arming, :before, :arm_weapons, :unless => :under_attack? ! # ... ! end
164. include! extend! prepend
165. Your characters can have of one another. DEMANDS and EXPECTATIONS
166. module AutoArming ! def fire_lasers @weapons_armed = true super end ! end ! class Base ! def fire_lasers puts 'PEW PEW PEW!' if @weapons_armed end ! end ! base = Base.new base.extend AutoArming base.fire_lasers # => PEW PEW PEW!
167. module AutoArming ! def fire_lasers @weapons_armed = true super end ! end ! class Base ! def fire_lasers puts 'PEW PEW PEW!' if @weapons_armed end ! end ! base = Base.new base.extend AutoArming base.fire_lasers # => PEW PEW PEW!
168. module AutoArming ! def fire_lasers @weapons_armed = true super end ! end ! class Base ! prepend AutoArming ! def fire_lasers puts 'PEW PEW PEW!' if @weapons_armed end ! end ! base = Base.new base.fire_lasers # => PEW PEW PEW!
169. module AutoArming ! def fire_lasers @weapons_armed = true super end ! end ! class Base ! prepend AutoArming ! def fire_lasers puts 'PEW PEW PEW!' if @weapons_armed end ! end ! base = Base.new base.fire_lasers # => PEW PEW PEW!
170. module AutoArming ! def fire_lasers @weapons_armed = true if should_autoarm? super end ! def should_autoarm? true end ! end class SecretBase < Base ! def should_autoarm? under_attack? end ! # ... ! end class Base ! prepend AutoArming ! def fire_lasers puts 'PEW PEW PEW!' if @weapons_armed end ! end
171. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend
172. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend Yes!
173. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend Yes! Yep!
174. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend Yes! It depends. Yep!
175. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend Yes! It depends. Yep! Eeeeyup!
176. What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5 Rules extend/prepend Yes! It depends. Yep! Eeeeyup! Free as the wind (through a branchless tree)
177. base.singleton_class.ancestors # => [AutoArming, Base, Object, Kernel, BasicObject] base.is_a?(AutoArming) # => true base._fire_lasers_callbacks # => [#<ActiveSupport::Callbacks::Callback:0x007...>] Callbacks: extend/prepend:
178. This is Ruby. I KNOW THIS!
179. Reduce Cognitive Load and win at being lazy.
181. We Are Storytellers
182. MAKE
 EVERY
 WORD! TELL
183. MAKE
 EVERY
 WORD! TELL❤️