Ruby - examples of cascading & namespacing

module-example.rb

# EXAMPLE 1: Cascade
# Two modules happen to have the same method ('say').
# If we include the Shouting module last, the Shouting 'say' method overwrites the Talkable 'say' method.

module Talkable
  def say (str)
    puts str
  end
end

module Shouting
  def say (str)
    puts str.upcase
  end
end

class Person
  include Talkable
  include Shouting
end

bob = Person.new
bob.say("hello")      # => 'HELLO' is capitalized because Shouting's 'say' method has precedence over Talking's 'say' method

module-example2.rb

# EXAMPLE2: Including part of a module using namespaces

module Greetings
  module English
    def hello
      puts "Hello"
    end
  end

  module French
    def hello
      puts "Bonjour"
    end
  end
end

class Person
  include Greetings::English      # getting just the English module within Greetings module.
end

bob = Person.new
bob.hello # => "Hello" rather than "Bonjour".

# Didn't include French module from Greetings, so it's not overwriting the English 'hello' method