Ruby Method-Calling Hierarchy Between Modules and Classes

modules_and_classes.rb

# Ruby Method-Calling Hierarchy.
#
# When a method is called Ruby :
#
# 1 - searches the method in class.
#
# 2- searches the method in each included modules
#    from the last one to the first one.
#
# Study Case:
#
# 1- A Cat is Wild but his Feline side is more visible.
#
# 2- A Tiger is a Feline but his Wild side is more visible.
#
# 3- A Bobcat is Wild and is a Feline.. BUT a Bobcat is a Bobcat.

module Wild
  def roar
    puts 'Wild: arrrrgh !'
  end
end

module Feline
  def roar
    puts 'Feline: miaou !'
  end
end

class Cat
  include Wild
  include Feline
end

class Tiger
  include Feline
  include Wild
end

class Bobcat
  include Feline
  include Wild

  def roar
    puts 'Bobcat: ... !'
  end
end

Cat.new.roar
Tiger.new.roar
Bobcat.new.roar

output

$> ruby modules_and_classes.rb
Feline: miaou !
Wild: arrrrgh !
Bobcat: ... !

$>