Weird Ruby (RubyDay 2024, Verona)

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Ciao!

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Third time is the charm!

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The best is yet to come…

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Bozhidar (Божидар)

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a.k.a. Bug (Бъг) / Bozho (Божо)

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@bbatsov

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✅ Older

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❌ Wiser

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Su + giu = sugiu

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Seiko 6105 (a.k.a. Captain Willard)

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Casio

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Open-Source Projects

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bbatsov

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Ruby & Rails style guides

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RuboCop supports Prism now! (In other words - RuboCop is faster)

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RuboCop turned 12 on April 21!

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Total Downloads: 424,020,934

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13 million downloads between Balkan Ruby & RubyDay! (1 month)

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#68

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RuboCop 1.64.1 is out today to celebrate RubyDay!

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Weird Ruby

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Dictionary de fi nitions

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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

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Weird != Bad

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Weird is Subjective

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ChatGPT, what are the 10 most weird features of the Ruby programming language?

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class String def shout self.upcase + "!!!" end end puts "hello".shout # Outputs: HELLO!!! 1. Monkey Patching

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2. Open classes class Integer def is_even? self % 2 == 0 end end puts 2.is_even? # Outputs: true

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3. Symbols puts :symbol.object_id == :symbol.object_id

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4. Block, procs and lambdas def execute_block(&block) block.call end execute_block { puts "Hello from a block!" }

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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)

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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

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7. Flexible syntax puts 'single quoted' puts "double quoted" puts %q{percent q} puts %Q{percent Q}

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8. Implicit returns def add(a, b) a + b end

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9. Self context changes class SelfExample def show_self puts self end end SelfExample.new.show_self # Outputs: #

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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

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Grazie! twitter: @bbatsov github: @bbatsov https://metaredux.com https://batsov.com RubyDay 2024 Verona, Italy 31.05.2024

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Ruby is 31 years old!

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Whatever doesn’t kill you simply makes you weirder. — The Joker

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Ground rules

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3 Levels of weirdness

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WAT

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Mamma mia!

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Ma sei serio!

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F**k This Sh*t

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Ma dai!

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Cosa c*zzo cosa!

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Che c*zzo e!

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Cosa c*zzo e!

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Holy sh*t!

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Madonna!

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The Contenders

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The (un)Usual Suspects…

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END { puts 'Bye!' } puts 'Processing...' BEGIN { puts 'Starting...' }

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DATA.each_line do |line| print(line) if (line =~ /begin/)..(line =~ /end/) end

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=begin comment line another comment line =end

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Must be placed at the very beginning of a line

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class SomeClass =begin This is a top comment. Or is it? =end def some_method end end

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class SomeClass =begin This is a top comment. Or is it? =end def some_method end end

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pry(main)> ?a => "a"

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irb> ?\C-\a => "\a" irb> ?\C-\M-\f => "\x8C"

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Reassignable constants

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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

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Class variables

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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"

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# 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

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Let’s get really weird!

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true || true && false

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true || (true && false)

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=> true

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true or true and false

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(true or true) and false

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=> false

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ENV

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{“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"}

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ENV.class

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ENV.class => Object

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012

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012 => 10

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0o12 => 10

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0b10 0o12 0xab

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1if 2 Yep

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def foo; 1return; end Nope

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++x

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+++-+++-+++x

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+++x => (+(+(+x)))

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Twitter -> X

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twitter.com -> x.com

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@batsov.net

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@bbatsov.hachyderm.io

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Object-Oriented Negation

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something.foo.! # double negation something.bar.!.! (x == y).! (x == y).!.! 10.!

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# Don't do this at home! class Integer def ! (1..self).reduce(:*) end end 5.! # => 120 !5 # => 120

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Incrementing Strings

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1.succ # => 2 (1..10).to_a # => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

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# 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"]

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# Examples in Bulgarian with Cyrilic letters below # Looking good! '1999б'.succ # => "1999в" # WAT!!! '1999я'.succ # => "1999ѐ"

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Positive & Negative Strings

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content = +"\n" content << "## #{title}\n" content << "\n" content

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# frozen_string_literal: true foo = "string" foo.upcase! # => FrozenError - can't modify frozen String (+foo).upcase! # => "STRING"

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Zeroing in on Zero!

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0.zero? # => true 0.nonzero? #=> nil 1.zero? #=> false 1.nonzero? #=> 1

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To In fi nity and Beyond!

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1. fi nite? => true 1.in fi nite? => nil Float::INFINITY. fi nite? => false Float::INFINITY.in fi nite? => 1

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Single-quoted Heredocs

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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

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# => "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"

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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

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# => "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"

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<<'END HTML' ... END HTML <<'\n!"£$%^&*()-=_+[];#{}:@~,./<>?|`\' hello \n!"£$%^&*()-=_+[];#{}:@~,./<>?|`\

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Nested Heredocs

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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

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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.

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Invoking Lambdas

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add_five = ->(x) { x + 5}

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add_five.call(10) # => 15

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add_five.(10) # => 15

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add_five[10] # => 15

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add_five.yield(10) # => 15

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add_five === 10 # => 15

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The Record for Most Aliases

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Hash#include?

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Hash#member?

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Hash#key?

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Hash#has_key?

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Honorable mentions

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Queue#pop Queue#deq Queue#shift Queue#push Queue#enq Queue#<< Enumerable#select Enumerable# fi lter Enumerable# fi nd_all

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Mixing Code & Data

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DATA.each_line do |line| puts line end __END__ I am Groot

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I am Groot

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Making something out of nothing!

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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)

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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)

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Explicit is better than implicit. Errors should never pass silently. In the face of ambiguity, refuse the temptation to guess.

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This is Ruuuuubyyyyy!!!

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Keep Ruby Weird!

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Grazie! twitter: @bbatsov github: @bbatsov https://metaredux.com https://batsov.com RubyDay 2024 Verona, Italy 31.05.2024