Instance variables (@) in Ruby - Mini Project: Build & Apply

Using Instance Variables (@) in Ruby Classes

📖 Scenario: Imagine you are creating a simple program to keep track of a book's details in a library system. Each book has a title and an author.

🎯 Goal: You will build a Ruby class called Book that uses instance variables to store the title and author of a book. Then, you will create an object of this class and display its details.

📋 What You'll Learn

Create a class named Book

Use instance variables @title and @author inside the class

Write an initialize method to set these instance variables

Create a method details that returns a string with the book's title and author

Create an object of Book with exact title 'The Ruby Way' and author 'Hal Fulton'

Print the details of the book object

💡 Why This Matters

🌍 Real World

Instance variables are used in real-world programs to store information unique to each object, like details of books, users, or products.

💼 Career

Understanding instance variables is essential for Ruby developers working on web applications, automation scripts, or any object-oriented programming tasks.

1

Create the Book class with an initialize method

Create a class called Book with an initialize method that takes two parameters: title and author. Inside the method, assign these parameters to instance variables @title and @author.

Ruby

class Book
  def initialize(title, author)
    # Your code here
  end
end

Need a hint?

Remember, instance variables start with @ and store data inside the object.

2

Add a method details to return book information

Inside the Book class, add a method called details that returns a string in the format: "Title: [title], Author: [author]" using the instance variables @title and @author.

Ruby

class Book
  def initialize(title, author)
    @title = title
    @author = author
  end

  # Define the details method below
  # Your code here
end

Need a hint?

Use string interpolation with #{} to include instance variables inside the string.

3

Create a Book object with given title and author

Create a variable called my_book and assign it a new Book object with the title 'The Ruby Way' and author 'Hal Fulton'.

Ruby

class Book
  def initialize(title, author)
    @title = title
    @author = author
  end

  def details
    "Title: #{@title}, Author: #{@author}"
  end
end

# Create the my_book object below
# Your code here

Need a hint?

Use ClassName.new(arguments) to create a new object.

4

Print the details of the my_book object

Write a puts statement to print the result of calling the details method on the my_book object.

Ruby

class Book
  def initialize(title, author)
    @title = title
    @author = author
  end

  def details
    "Title: #{@title}, Author: #{@author}"
  end
end

my_book = Book.new('The Ruby Way', 'Hal Fulton')

# Print the book details below
# Your code here

Need a hint?

Use puts object.method to print the returned string.