Enumerator.is_an(Enumerable) [es]

madrid-rb (Madrid Ruby Users Group) September 2015

Transcript

1. Enumerator.is_an(Enumerable) Sergio Gil iamserg.io / @porras madrid-rb Septiembre 2015
2. Everyone ❤ Enumerable
3. Everyone ❤ Enumerable FACT
4. x.map { |i| i * i } # [1, 4, 9, 16, ...]
5. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1
6. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9
7. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false
8. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true
9. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true x.detect { |i| i > 5 } # 6
10. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true x.detect { |i| i > 5 } # 6 x.reduce(&:*) # 362880
11. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true x.detect { |i| i > 5 } # 6 x.reduce(&:*) # 362880 x.select(&:odd?) # [1, 3, 5, 7, 9]
12. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true x.detect { |i| i > 5 } # 6 x.reduce(&:*) # 362880 x.select(&:odd?) # [1, 3, 5, 7, 9] x.take_while { |i| i < 5 } # [1, 2, 3, 4]
13. x.group_by { |i| i % 3 }
 # {0 => [3, 6, 9], 1 => [1, 4, 7], 2 => [2, 5, 8]}

14. x.group_by { |i| i % 3 }
 # {0 => [3, 6, 9], 1 => [1, 4, 7], 2 => [2, 5, 8]}
 x.each_slice(3) { |slice| p slice }
 # [1, 2, 3]
 # [4, 5, 6]
 # [7, 8, 9]

15. x.group_by { |i| i % 3 }
 # {0 => [3, 6, 9], 1 => [1, 4, 7], 2 => [2, 5, 8]}
 x.each_slice(3) { |slice| p slice }
 # [1, 2, 3]
 # [4, 5, 6]
 # [7, 8, 9]
 x.each_slice(3).map { |slice| slice.first }
 # [1, 4, 7]

16. x.group_by { |i| i % 3 }
 # {0 => [3, 6, 9], 1 => [1, 4, 7], 2 => [2, 5, 8]}
 x.each_slice(3) { |slice| p slice }
 # [1, 2, 3]
 # [4, 5, 6]
 # [7, 8, 9]
 x.each_slice(3).map { |slice| slice.first }
 # [1, 4, 7]
 x.partition(&:odd?)
 # [[1, 3, 5, 7, 9], [2, 4, 6, 8]]
17. http://www.rubydoc.info/stdlib/core/Enumerable
18. x.map { |i| i * i } # [1, 4, 9, 16, ...] x.min # 1 x.max # 9 x.all? { |i| i < 5 } # false x.any?(&:odd?) # true x.detect { |i| i > 5 } # 6 x.reduce(&:*) # 362880 x.select(&:odd?) # [1, 3, 5, 7, 9] x.take_while { |i| i < 5 } # [1, 2, 3, 4]
19. Pero, ¿qué es x?
21. No necesariamente .
22. http://www.rubydoc.info/stdlib/core/Enumerable
23. ¿Y qué es un Enumerable?
25. x = (1..9)
26. ¡Mi propio Enumerable!
27. 1. Implementar #each
28. 1. Implementar #each 2. include Enumerable
29. 1. Implementar #each 2. include Enumerable 3. No hay paso 3
30. three = [1, 2, 3] three.each { |i| puts i } three.map { |i| i * i } three.select(&:odd?) three.max three.first three.reduce(&:+)
31. class Three include Enumerable def each yield 1 yield 2 yield 3 end end three = Three.new three.each { |i| puts i } three.map { |i| i * i } three.select(&:odd?) three.max three.first three.reduce(&:+)
32. En resumen:
33. En resumen: Enumerable mola.
34. En resumen: Enumerable mola. Para crear tus propios Enumerables, implementa #each.
35. Enumerator: una forma fácil de implementar #each
36. (y no hace falta incluir Enumerable)
37. Fact 1. Acepta un bloque pero no lo ejecuta (lo guarda)
38. Fact 1. Acepta un bloque pero no lo ejecuta (lo guarda) my_enum = Enumerator.new { raise '' } # no pasa nada
39. Fact 2. Implementa #each, incluye Enumerable
40. Fact 2. Implementa #each, incluye Enumerable my_enum.respond_to?(:each) # true
41. Fact 2. Implementa #each, incluye Enumerable my_enum.respond_to?(:each) # true my_enum.is_a?(Enumerable) # true
42. ¿Y qué hace #each?
43. Pues ejecuta al bloque (fact 3)
44. Pues ejecuta al bloque (fact 3) my_enum.each {} # example.rb:6:in `block in <main>': (RuntimeError) # from examples/facts.rb:16:in `each' # from examples/facts.rb:16:in `each' # from examples/facts.rb:16:in `<main>'
45. my_enum = Enumerator.new do |e| e << '¡hola!' end my_enum.each do |item| p item end # "¡hola!"
46. my_enum = [].tap do |a| a << '¡hola!' end my_enum.each do |item| p item end # "¡hola!"
49. Bola extra: Enumerator::Lazy
50. Bola extra: Enumerator::Lazy my_enum.map(&:upcase).class # Array
51. Bola extra: Enumerator::Lazy my_enum.map(&:upcase).class # Array my_enum.lazy.map(&:upcase).class # Enumerator::Lazy
52. ¡Chaining! ¡Incluso en secuencias infinitas! Fibonacci.numbers.select { |i| i % 5 == 0 }. take_while { |i| i < 10 ** 6 }
53. ¡Chaining! ¡Incluso en secuencias infinitas! Fibonacci.numbers.select { |i| i % 5 == 0 }. take_while { |i| i < 10 ** 6 } # [0, 5, 55, 610, 6765, 75025, 832040]
56. class Clock def self.seconds Enumerator.new do |e| loop do e << Time.now.to_i sleep 1 end end.lazy end end
57. class Clock def self.seconds Enumerator.new do |e| loop do e << Time.now.to_i sleep 1 end end.lazy end end Clock.seconds.select(&:odd?).take(5).each do |time| p time end
58. class Clock def self.seconds Enumerator.new do |e| loop do e << Time.now.to_i sleep 1 end end.lazy end end Clock.seconds.select(&:odd?).take(5).each do |time| p time end # 1435648191 # 1435648193 # 1435648195 # 1435648197 # 1435648199
59. class Clock ... def self.minutes seconds.select { |t| t % 60 == 0 } end end
61. CLOUDSOUND
62. { "tracks": [ { "id": 1, "duration": 37, "title": "Tools", "artist": "Tess Goyette Jr." }, ..., { "id": 11, "duration": 153, "title": "Grocery", "artist": "Geovanni McKenzie" } ], "meta": { "next": "http://localhost:4567/tracks?after=11" } } GET /tracks
63. { "tracks": [ { "id": 12, "duration": 153, "title": "Jewelery", "artist": "Berniece Hayes" }, ... { "id": 21, "duration": 161, "title": "Grocery & Beauty", "artist": "Adah Kozey" } ], "meta": { "next": "http://localhost:4567/tracks?after=21" } } GET /tracks?after=11
64. class Api def initialize(url) @url = url end def tracks url = "#{@url}/tracks" Enumerator.new do |e| loop do data = get(url) data['tracks'].each do |track| e << track end url = data['meta']['next'] end end.lazy end end
65. > api = Api.new('http://localhost:4567') => <Api:0x007fa96c0e1150 @url="http://localhost:4567">
66. > api = Api.new('http://localhost:4567') => <Api:0x007fa96c0e1150 @url="http://localhost:4567"> > api.tracks => <Enumerator::Lazy: <Enumerator: <Enumerator::Generator: 0x007fa96c0d9478>:each>>
67. > api = Api.new('http://localhost:4567') => <Api:0x007fa96c0e1150 @url="http://localhost:4567"> > api.tracks => <Enumerator::Lazy: <Enumerator: <Enumerator::Generator: 0x007fa96c0d9478>:each>> > api.tracks.first => {"id"=>1, "duration"=>37, "title"=>"Tools", "artist"=>"Tess Goyette Jr."}
68. > api = Api.new('http://localhost:4567') => <Api:0x007fa96c0e1150 @url="http://localhost:4567"> > api.tracks => <Enumerator::Lazy: <Enumerator: <Enumerator::Generator: 0x007fa96c0d9478>:each>> > api.tracks.first => {"id"=>1, "duration"=>37, "title"=>"Tools", "artist"=>"Tess Goyette Jr."} > api.tracks.drop(15).first => {"id"=>16, "duration"=>192, "title"=>"Clothing & Books", "artist"=>"Vicente Dickens"}
69. > api = Api.new('http://localhost:4567') => <Api:0x007fa96c0e1150 @url="http://localhost:4567"> > api.tracks => <Enumerator::Lazy: <Enumerator: <Enumerator::Generator: 0x007fa96c0d9478>:each>> > api.tracks.first => {"id"=>1, "duration"=>37, "title"=>"Tools", "artist"=>"Tess Goyette Jr."} > api.tracks.drop(15).first => {"id"=>16, "duration"=>192, "title"=>"Clothing & Books", "artist"=>"Vicente Dickens"} > api.tracks.detect { |t| t['duration'] == 180 } => {"id"=>157, "duration"=>180, "title"=>"Health & Games", "artist"=>"Kareem Tillman DDS"}
70. > total_duration = 0 => 0
71. > total_duration = 0 => 0
72. > total_duration = 0 => 0 > api.tracks.select { |track| track['duration'] > 120 }.take_while { |track| (total_duration += track['duration']) < 90 * 60 }.to_a
73. > total_duration = 0 => 0 > api.tracks.select { |track| track['duration'] > 120 }.take_while { |track| (total_duration += track['duration']) < 90 * 60 }.to_a
74. > total_duration = 0 => 0 > api.tracks.select { |track| track['duration'] > 120 }.take_while { |track| (total_duration += track['duration']) < 90 * 60 }.to_a => [{"id"=>2, "duration"=>144, "title"=>"Toys & Garden", "artist"=>"Rossie Senger"}, {"id"=>4, "duration"=>234, "title"=>"Baby", "artist"=>"Scottie Kling"}, {"id"=>5, "duration"=>215, "title"=>"Jewelery & Books", "artist"=>"Marge Simonis"}, {"id"=>7, "duration"=>216, "title"=>"Outdoors & Clothing", "artist"=>"Cortez Windler"}, {"id"=>11, "duration"=>153, "title"=>"Grocery", "artist"=>"Geovanni McKenzie"}, {"id"=>11, "duration"=>153, "title"=>"Jewelery", "artist"=>"Berniece Hayes"}, {"id"=>13, "duration"=>132, "title"=>"Toys, Movies & Health", "artist"=>"Joel Kuhlman"}, {"id"=>14, "duration"=>212, "title"=>"Jewelery & Games", "artist"=>"Jalyn Langosh"}, {"id"=>15, "duration"=>192, "title"=>"Clothing & Books", "artist"=>"Vicente Dickens"}, {"id"=>17, "duration"=>223, "title"=>"Industrial & Garden", "artist"=>"Archibald
75. > total_duration = 0 => 0 > api.tracks.select { |track| track['duration'] > 120 }.take_while { |track| (total_duration += track['duration']) < 90 * 60 }.to_a => [{"id"=>2, "duration"=>144, "title"=>"Toys & Garden", "artist"=>"Rossie Senger"}, {"id"=>4, "duration"=>234, "title"=>"Baby", "artist"=>"Scottie Kling"}, {"id"=>5, "duration"=>215, "title"=>"Jewelery & Books", "artist"=>"Marge Simonis"}, {"id"=>7, "duration"=>216, "title"=>"Outdoors & Clothing", "artist"=>"Cortez Windler"}, {"id"=>11, "duration"=>153, "title"=>"Grocery", "artist"=>"Geovanni McKenzie"}, {"id"=>11, "duration"=>153, "title"=>"Jewelery", "artist"=>"Berniece Hayes"}, {"id"=>13, "duration"=>132, "title"=>"Toys, Movies & Health", "artist"=>"Joel Kuhlman"}, {"id"=>14, "duration"=>212, "title"=>"Jewelery & Games", "artist"=>"Jalyn Langosh"}, {"id"=>15, "duration"=>192, "title"=>"Clothing & Books", "artist"=>"Vicente Dickens"}, {"id"=>17, "duration"=>223, "title"=>"Industrial & Garden", "artist"=>"Archibald
76. $ ruby examples/mixtape/mixtape.rb 45
77. $ ruby examples/mixtape/mixtape.rb 45 14 tracks (44:17) Rossie Senger - Toys & Garden (2:24) Scottie Kling - Baby (3:54) Marge Simonis - Jewelery & Books (3:35) Cortez Windler - Outdoors & Clothing (3:36) Geovanni McKenzie - Grocery (2:33) Berniece Hayes - Jewelery (2:33) Joel Kuhlman - Toys, Movies & Health (2:12) Jalyn Langosh - Jewelery & Games (3:32) Vicente Dickens - Clothing & Books (3:12) Archibald Huels - Industrial & Garden (3:43) Adah Kozey - Grocery & Beauty (2:41) Mr. Geo Torp - Electronics (3:21) Doug Lesch - Jewelery, Health & Tools (3:08) Esta Daugherty - Shoes & Baby (3:53)
78. En resumen:
79. En resumen: Enumerable: hacer magia con listas.
80. En resumen: Enumerable: hacer magia con listas. Enumerator: hacer listas con cualquier cosa.
81. ¡Gracias! Sergio Gil iamserg.io / @porras madrid-rb septiembre 2015 https://github.com/porras/enumerator-talk
82. ¡Gracias! ¿Preguntas? Sergio Gil iamserg.io / @porras madrid-rb septiembre 2015 https://github.com/porras/enumerator-talk
83. El pequeño y oscuro secreto de esta charla
84. Como en un koan
85. cuando el aprendiz finalmente entienda Enumerator
86. se dará cuenta de que
87. no necesita Enumerator
88. no hay Enumerator
89. Enumerator es #each
90. Enumerator es #each #each es Enumerator
91. class Api def initialize(url) @url = url end def tracks url = "#{@url}/tracks" Enumerator.new do |e| loop do data = get(url) data['tracks'].each do |track| e << track end url = data['meta']['next'] end end.lazy end end
92. class Api def initialize(url) @url = url end def tracks Tracks.new("#{@url}/tracks").lazy end class Tracks def initialize(url) @url = url end def each url = @url loop do data = get(url) data['tracks'].each do |track| yield track end url = data['meta']['next'] end end include Enumerable end end https://github.com/porras/enumerator-talk/tree/no-enumerator
93. y el aprendiz habrá entendido