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Polymorphism using Inheritance in Ruby

Ruby | Polymorphism using Inheritance: In this tutorial, we are going to learn about the Polymorphism using Inheritance in Ruby programming language with examples.
Submitted by Hrithik Chandra Prasad, on April 10, 2020

Ruby | Polymorphism using Inheritance

In this tutorial, we will study about polymorphism in Ruby. We all know that Ruby is a pure object-oriented language and polymorphism is one of the very important features of any object-oriented language. You must be having a little difficulty in understanding the topic with its title, but do not worry, you will be having your all doubts clear after going through the article. The rest of the content is all about polymorphism in Ruby along with syntaxes and demonstrating program codes for your better understanding.

We all know this but let me repeat this that Polymorphism is an addition of two words which are "poly" and "Morph". Here the word "poly" means many and "Morph" means forms. So collectively we can say that Polymorphism is a property in which something has many forms. SP, in computer terminology, polymorphism can be called as a method in which a user can invoke the same method passing different objects as parameters.

Polymorphism is a property in which classes have different types of functions but they share the same interface. Polymorphism can be studied under two types of sub-categories which are namely

• Polymorphism with the help of Inheritance
• Polymorphism with the help of Duck-Typing

In this tutorial, we will only study a subcategory which is Polymorphism with the help of Inheritance.

Let us understand Inheritance first, it is a property in which child class inherits the property of parent class.

You can understand the implementation of polymorphism with the help of inheritance with the help of following program code,

Example:

=begin
  Ruby program to demonstrate polymorphism 
  with Inheritance
=end	

class Fruit
  def tastetype
    puts "Sour fruit."
  end
end

class Orange<Fruit
  def tastetype
    puts "Sour-Sweet Fruit"
  end
end

class Apple<Fruit
  def tastetype
    puts "Sweet Fruit"
  end
end

fruit = Fruit.new
fruit.tastetype
fruit = Orange.new
fruit.tastetype
fruit = Apple.new
fruit.tastetype 

Output

Sour fruit.
Sour-Sweet Fruit
Sweet Fruit

Explanation:

With the help of the above code, you must have got a clear understanding of Polymorphism with the help of Inheritance. Here the method tastetype is invoked with the help of objects Orange and Apple. The Orange and Apple classes have the same parent class fruit. tastetype is the method which they have inherited from their parent class Fruit.

Now, let us understand Duck Typing, it is nothing but an idea to see what can be done by an object instead of what it can do or in the other words you can say that what can be implemented on the object rather than on the class of the instance.

You can understand the implementation of polymorphism with the help of duck typing with the help of following program code,

Example:

=begin
  Ruby program to demonstrate polymorphism 
  using duck typing
=end	

class College
  def enters
    puts "A student enters"
  end
  
  def type(student)
    student.type
  end
  
  def course(student)
    student.course
  end
end

class Ug
  def type
    puts "student is a under graduate student"
  end
  
  def course
    puts "BCA student"
  end
end

class Pg
  def type
    puts "student is a post graduate student"
  end
  
  def course
    puts "MCA student"
  end
end

college = College.new
puts "This student is Under graduate"
stu = Ug.new
college.type(stu)
college.course(stu)

puts "This student is Post graduate"
stu = Pg.new
college.type(stu)
college.course(stu)

Output

This student is Under graduate
student is a under graduate student
BCA student
This student is Post graduate
student is a post graduate student
MCA student

Explanation:

With the help of the above code, you must have got a clear understanding of Polymorphism with the help of Duck Typing. Here the object stu is playing a role in working with the functionalities of the class College such as its type and its course.