Weird Ruby (RubyDay 2024, Verona)

A weird talk. :-)

Transcript

2. Ciao!
13. Third time is the charm!
14. The best is yet to come…
15. Bozhidar (Божидар)
16. a.k.a. Bug (Бъг) / Bozho (Божо)
17. @bbatsov
20. ✅ Older
21. ❌ Wiser
28. Su + giu = sugiu
33. Seiko 6105 (a.k.a. Captain Willard)
36. Casio
41. Open-Source Projects
42. bbatsov
43. Ruby & Rails style guides
45. RuboCop supports Prism now! (In other words - RuboCop is faster)
47. RuboCop turned 12 on April 21!
48. Total Downloads: 424,020,934
49. 13 million downloads between Balkan Ruby & RubyDay! (1 month)
50. #68
51. RuboCop 1.64.1 is out today to celebrate RubyDay!
52. Weird Ruby
53. Dictionary de fi nitions
56. A dynamic, open source programming language with a focus on simplicity and productivity. It has an elegant syntax that is natural to read and easy to write. — ruby-lang.org
57. Weird != Bad
58. Weird is Subjective
59. ChatGPT, what are the 10 most weird features of the Ruby programming language?
60. class String def shout self.upcase + "!!!" end end puts "hello".shout # Outputs: HELLO!!! 1. Monkey Patching
61. 2. Open classes class Integer def is_even? self % 2 == 0 end end puts 2.is_even? # Outputs: true
62. 3. Symbols puts :symbol.object_id == :symbol.object_id
63. 4. Block, procs and lambdas def execute_block(&block) block.call end execute_block { puts "Hello from a block!" }
64. 5. Method missing class DynamicMethods def method_missing(name, *args) puts "Called #{name} with #{args}" end end dm = DynamicMethods.new dm.some_method(1, 2, 3)
65. 6. Metaprogramming class MetaClass def self.create_method(name) define_method(name) { puts "#{name} method called" } end end MetaClass.create_method(:dynamic) obj = MetaClass.new obj.dynamic # Outputs: dynamic method called
66. 7. Flexible syntax puts 'single quoted' puts "double quoted" puts %q{percent q} puts %Q{percent Q}
67. 8. Implicit returns def add(a, b) a + b end
68. 9. Self context changes class SelfExample def show_self puts self end end SelfExample.new.show_self # Outputs: #<SelfExample:0x0000560c7c8b3a00>
69. 10. Keyword arguments with default values def greet(name:, greeting: "Hello") puts "#{greeting}, #{name}" end greet(name: "Alice") # Outputs: Hello, Alice greet(name: "Bob", greeting: "Hi") # Outputs: Hi, Bob
71. Grazie! twitter: @bbatsov github: @bbatsov https://metaredux.com https://batsov.com RubyDay 2024 Verona, Italy 31.05.2024
72. Ruby is 31 years old!
73. Whatever doesn’t kill you simply makes you weirder. — The Joker
74. Ground rules
75. 3 Levels of weirdness
76. 1.
77. WAT
78. Mamma mia!
79. Ma sei serio!
80. 2.
81. F**k This Sh*t
83. Ma dai!
84. Cosa c*zzo cosa!
85. Che c*zzo e!
86. Cosa c*zzo e!
87. 3.
88. Holy sh*t!
89. Madonna!
90. The Contenders
91. The (un)Usual Suspects…
92. END { puts 'Bye!' } puts 'Processing...' BEGIN { puts 'Starting...' }
93. DATA.each_line do |line| print(line) if (line =~ /begin/)..(line =~ /end/) end
94. =begin comment line another comment line =end
95. Must be placed at the very beginning of a line
96. class SomeClass =begin This is a top comment. Or is it? =end def some_method end end
97. class SomeClass =begin This is a top comment. Or is it? =end def some_method end end
98. pry(main)> ?a => "a"
99. irb> ?\C-\a => "\a" irb> ?\C-\M-\f => "\x8C"
100. Reassignable constants
101. pry(main)> A = 5 => 5 pry(main)> A = 6 (pry):39: warning: already initialized constant A (pry):38: warning: previous definition of A was here => 6 pry(main)> Class = 3 (pry):40: warning: already initialized constant Class => 3 pry(main)> Class => 3
103. Class variables
104. class Parent @@class_var = 'parent' def self.print_class_var puts @@class_var end end class Child < Parent @@class_var = 'child' end Parent.print_class_var # => will print "child"
105. # Unintended usage: the variable is defined in the child, but then the parent changes it class Bad def self.corrupt_registry! @@registry = [] end end class BadChild < Bad @@registry = {} # This is some variable which meant to belong to THIS class def self.registry @@registry end end Bad.corrupt_registry! # Probably unexpected for BadChild's author, its ancestor have changed the variable BadChild.registry # On the next attempt to _access_ the variable the error will be raised # 2.7: => [] # 3.0: RuntimeError (class variable @@registry of BadChild is overtaken by Bad) Ruby 3.0 changes
106. Let’s get really weird!
107. true || true && false
108. true || (true && false)
109. => true
110. true or true and false
111. (true or true) and false
112. => false
113. ENV
114. {“COLORFGBG"=>"7;0", "COLORTERM"=>"truecolor", "COMMAND_MODE"=>"unix2003", "GEM_HOME"=>"/Users/bbatsov/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0", "HOME"=>"/Users/bbatsov", "HOMEBREW_CELLAR"=>"/opt/homebrew/Cellar", "HOMEBREW_PREFIX"=>"/opt/homebrew", “HOMEBREW_REPOSITORY"=>"/opt/homebrew"}
115. ENV.class
116. ENV.class => Object
118. 012 => 10
120. 0o12 => 10
121. 0b10 0o12 0xab
122. 1if 2 Yep
123. def foo; 1return; end Nope
124. ++x
125. +++-+++-+++x
126. +++x => (+(+(+x)))
127. X
128. Twitter -> X
129. twitter.com -> x.com
130. @batsov.net
131. @bbatsov.hachyderm.io
132. Object-Oriented Negation
133. something.foo.! # double negation something.bar.!.! (x == y).! (x == y).!.! 10.!
134. # Don't do this at home! class Integer def ! (1..self).reduce(:*) end end 5.! # => 120 !5 # => 120
135. Incrementing Strings
136. 1.succ # => 2 (1..10).to_a # => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
138. # looking good ('1.0'..'1.5').to_a # => ["1.0", "1.1", "1.2", "1.3", "1.4", "1.5"] # oh, shit! ('1.0'..'1.10').to_a # => ["1.0", # "1.1", # "1.2", # "1.3", # "1.4", # "1.5", # "1.6", # "1.7", # "1.8", # "1.9", # "2.0", # "2.1", # ... # "99.9"]
139. # Examples in Bulgarian with Cyrilic letters below # Looking good! '1999б'.succ # => "1999в" # WAT!!! '1999я'.succ # => "1999ѐ"
140. Positive & Negative Strings
141. content = +"\n" content << "## #{title}\n" content << "\n" content
142. # frozen_string_literal: true foo = "string" foo.upcase! # => FrozenError - can't modify frozen String (+foo).upcase! # => "STRING"
143. Zeroing in on Zero!
144. 0.zero? # => true 0.nonzero? #=> nil 1.zero? #=> false 1.nonzero? #=> 1
145. To In fi nity and Beyond!
146. 1. fi nite? => true 1.in fi nite? => nil Float::INFINITY. fi nite? => false Float::INFINITY.in fi nite? => 1
147. Single-quoted Heredocs
148. land = 'Mordor' verse = <<-TEXT One Ring to rule them all, One Ring to find them, One Ring to bring them all, and in the darkness bind them, In the Land of #{land} where the Shadows lie. TEXT
149. # => "One Ring to rule them all,\n" + # "One Ring to find them,\n" + # "One Ring to bring them all,\n" + # "and in the darkness bind them,\n" + # "In the Land of Mordor where the Shadows lie.\n"
150. land = 'Mordor' verse = <<-'TEXT' One Ring to rule them all, One Ring to find them, One Ring to bring them all, and in the darkness bind them, In the Land of #{land} where the Shadows lie. TEXT
151. # => "One Ring to rule them all,\n" + # "One Ring to find them,\n" + # "One Ring to bring them all,\n" + # "and in the darkness bind them,\n" + # "In the Land of \#{land} where the Shadows lie.\n"
152. <<'END HTML' <html> ... </html> END HTML <<'\n!"£$%^&*()-=_+[];#{}:@~,./<>?|`\' hello \n!"£$%^&*()-=_+[];#{}:@~,./<>?|`\
153. Nested Heredocs
154. outer = <<-OUTER This is the outer heredoc. It contains an inner heredoc: #{<<-INNER} This is the inner heredoc. It is nested within the outer heredoc. It can contain its own multi-line text. INNER The outer heredoc continues here. OUTER
155. This is the outer heredoc. It contains an inner heredoc: This is the inner heredoc. It is nested within the outer heredoc. It can contain its own multi-line text. The outer heredoc continues here.
157. Invoking Lambdas
158. add_five = ->(x) { x + 5}
159. add_five.call(10) # => 15
160. add_five.(10) # => 15
161. add_five[10] # => 15
162. add_five.yield(10) # => 15
163. add_five === 10 # => 15
165. The Record for Most Aliases
166. Hash#include?
167. Hash#member?
168. Hash#key?
169. Hash#has_key?
171. Honorable mentions
172. Queue#pop Queue#deq Queue#shift Queue#push Queue#enq Queue#<< Enumerable#select Enumerable# fi lter Enumerable# fi nd_all
173. Mixing Code & Data
174. DATA.each_line do |line| puts line end __END__ I am Groot
175. I am Groot
176. Making something out of nothing!
177. irb(main):001:0> nil.to_h => {} irb(main):002:0> nil.to_a => [] irb(main):003:0> nil.to_s => "" irb(main):004:0> nil.to_f => 0.0 irb(main):005:0> nil.to_i => 0 irb(main):006:0> nil.to_c => (0+0i)
178. irb(main):001:0> Array(nil) => [] irb(main):002:0> Hash(nil) => {} irb(main):003:0> Integer(nil) # `Integer': can't convert nil into Integer (TypeError) irb(main):004:0> Float(nil) # `Float': can't convert nil into Float (TypeError)
179. Explicit is better than implicit. Errors should never pass silently. In the face of ambiguity, refuse the temptation to guess.
180. This is Ruuuuubyyyyy!!!
181. Keep Ruby Weird!
182. Grazie! twitter: @bbatsov github: @bbatsov https://metaredux.com https://batsov.com RubyDay 2024 Verona, Italy 31.05.2024