Code snippets for a Suma lightning talk

0_super.rb

module Greeting
  def greet(who)
    "Hello #{who}"
  end
end

class Hacker
  include Greeting

  def greet(who)
    if who.downcase == who
      "hi @#{who}"
    else
      super
    end
  end
end

hacker = Hacker.new
hacker.greet('Damián S') # => "Hello Damián S"
hacker.greet('nox') # => "hi @nox"

1_monk.rb

# Example totally stolen from RubyMonk.

class Monk
  %w(life the_universe everything).each do |concept|
    define_method("meditate_on_#{concept}") do
      "I know the meaning of #{concept.tr '_', ' '}"
    end
  end
end

monk = Monk.new
monk.meditate_on_life

2_naive_module.rb

module Meditation
  def can_meditate_on(*concepts)
    concepts.each do |concept|
      define_method("meditate_on_#{concept}") do
        "I know the meaning of #{concept.to_s.tr '_', ' '}"
      end
    end
  end
end

class Newbie
  extend Meditation
  can_meditate_on :variables, :blocks

  def meditate_on_blocks
    "#{super}, i think..."
  end
end

newbie = Newbie.new
newbie.meditate_on_blocks

3_dynamic_module.rb

module Meditation
  def can_meditate_on(*concepts)
    if const_defined?(:MeditationMethods, _search_ancestors = false)
      mod = const_get(:MeditationMethods)
    else
      mod = const_set(:MeditationMethods, Module.new)
      include mod
    end

    mod.module_eval do
      concepts.each do |concept|
        define_method("meditate_on_#{concept}") do
          "I know the meaning of #{concept.to_s.tr '_', ' '}"
        end
      end
    end
  end
end


class Newbie
  extend Meditation
  can_meditate_on :variables, :blocks

  def meditate_on_blocks
    "#{super}, i think..."
  end
end

newbie = Newbie.new
newbie.meditate_on_blocks # => "I know the meaning of blocks, i think..."

4_simple_dynamic_module.rb

module Meditation
  def self.on(*concepts)
    Module.new do
      concepts.each do |concept|
        define_method("meditate_on_#{concept}") do
          "I know the meaning of #{concept.to_s.tr '_', ' '}"
        end
      end
    end
  end
end

class Guru
  include Meditation.on(:modules)

  def meditate_on_modules
    "#{super} and more!"
  end
end

guru = Guru.new
guru.meditate_on_modules # => "I know the meaning of modules and more!"