Lets say that you have a situation where you need to code about dogs. You know that there are different kind of dogs and you end up with a code structure as shown

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

module Animal
  module Domestic
    class Dog
      def sound
        "woof"
      end
    end
  end

  module Wild
    class Dog
      def sound
        "grrr"
      end
    end
  end
end

So there are two kinds of dogs, one is wild that can be accessed like Animal::Wild::Dog and other one is Domestic which could be accessed in similar way.

So if you want to print out how Domestic and Wild dog sounds like you can write a program as shown:

1
2
3
4
5
6
7
8

# using_dog_in_animal_module.rb

require_relative "dog_in_animal_module.rb"

include Animal

puts Domestic::Dog.new.sound
puts Wild::Dog.new.sound

But if you look I am using something like this Domestic::Dog.new.sound which is long to code and tax my fingers, what if I could do something that would make my typing shorter? Fortunately you can do that in Ruby. See the program below:

1
2
3
4
5
6
7
8
9

# renaming_class.rb

require_relative "dog_in_animal_module.rb"

DomesticDog = Animal::Domestic::Dog
WildDog = Animal::Wild::Dog

puts DomesticDog.new.sound
puts WildDog.new.sound

In the code above, notice line 5 and line 6, we are kinda reaming the class. Rather using the long form Animal::Domestic::Dog we simply assign it to a constant name DomesticDog as shown DomesticDog = Animal::Domestic::Dog and in line 8 we can use it short like puts DomesticDog.new.sound.

In a large programming environment, we would have reduced lot of typing. Happy coding! :)

Notes