Polymorphism in Ruby

In Ruby, one does not have anything like the variable types as there is in other programming languages. Every variable is an “object” which can be individually modified. One can easily add methods and functions on every object. So here, the Object Oriented Programming plays a major role. There are many pillars of Object Oriented Programming in every other programming language, like Inheritance, Encapsulation etc. One of these pillars is Polymorphism.

Polymorphism is a made up of two words Poly which means Many and Morph which means Forms. So Polymorphism is a method where one is able to execute the same method using different objects. In polymorphism, we can obtain different results using the same function by passing different input objects. One can also write the If-Else commands but that just makes the code more lengthy. To avoid this, the programmers came up with the concept of polymorphism.

In Polymorphism, classes have different functionality but they share common interference. The concept of polymorphism can be studied under few sub categories.

1. Polymorphism using Inheritance
2. Polymorphism using Duck-Typing

• Polymorphism using inheritance
  Inheritance is a property where a child class inherits the properties and methods of a parent class. One can easily implement polymorphism using inheritance. It can be explained using the following example:
  Example :

  # Ruby program of Polymorphism using inheritance
  class Vehicle
      def tyreType
          puts "Heavy Car"
      end
  end
  
  # Using inheritance
  class Car < Vehicle
      def tyreType
          puts "Small Car"
      end
  end
  
  # Using inheritance
  class Truck < Vehicle
      def tyreType
          puts "Big Car"
      end
  end
  
  # Creating object
  vehicle = Vehicle.new
  vehicle.tyreType()
  
  # Creating different object calling same function
  vehicle = Car.new
  vehicle.tyreType()
  
  # Creating different object calling same function
  vehicle = Truck.new
  vehicle.tyreType()

  Output:

  Heavy Car
  Small Car
  Big Car

  The above code is a very simple way of executing basic polymorphism. Here, the tyreType method is called using different objects like Car and Truck. The Car and Truck classes both are the child classes of Vehicle. They both inherit the methods of vehicle class (primarily the tyretype method).

• Polymorphism using Duck-Typing
  In Ruby, we focus on the object’s capabilities and features rather than its class. So, Duck Typing is nothing but working on the idea of what an object can do rather than what it actually is. Or, what operations could be performed on the object rather than the class of the object.
  Here is a small program to represent the before mentioned process.
  Example :

  # Ruby program of polymorphism using Duck typing
  
  # Creating three different classes
  class Hotel
  
    def enters
      puts "A customer enters"
    end
  
    def type(customer)
      customer.type
    end
  
    def room(customer)
      customer.room
    end
  
  end
  
  # Creating class with two methods
  class Single
  
    def type
      puts "Room is on the fourth floor."
    end
  
    def room
      puts "Per night stay is 5 thousand"
    end
  
  end
  
  
  class Couple
  
   # Same methods as in class single
    def type
      puts "Room is on the second floor"
    end
  
    def room
      puts "Per night stay is 8 thousand"
    end
  
  end
  
  # Creating Object
  # Performing polymorphism
  hotel= Hotel.new
  puts "This visitor is Single."
  customer = Single.new
  hotel.type(customer)
  hotel.room(customer)
  
  
  puts "The visitors are a couple."
  customer = Couple.new
  hotel.type(customer)
  hotel.room(customer)

  Output :

  This visitor is Single.
  Room is on the fourth floor.
  Per night stay is 5 thousand
  The visitors are a couple.
  Room is on the second floor
  Per night stay is 8 thousand
  

  In the above example, The customer object plays a role in working with the properties of the customer such as its “type” and its “room”. This is an example of polymorphism.