Object#dup and Object#clone in Ruby - Mini Project: Build & Apply

Understanding Object#dup and Object#clone in Ruby

📖 Scenario: Imagine you have a simple Ruby object representing a book in a library system. You want to create copies of this book object to make changes without affecting the original.

🎯 Goal: You will learn how to create copies of an object using dup and clone methods in Ruby, and observe the differences between them.

📋 What You'll Learn

Create a Ruby class called Book with attributes title and author

Create an instance of Book with specific values

Create copies of the book object using dup and clone

Print the original and copied objects to compare

💡 Why This Matters

🌍 Real World

Copying objects is useful when you want to work with similar data without changing the original, like duplicating a book record to edit details safely.

💼 Career

Understanding object copying helps in Ruby programming for tasks like caching, undo features, or managing state without side effects.

1

Create the Book class and an instance

Create a Ruby class called Book with an initialize method that takes title and author as parameters and sets them as instance variables. Then create an instance called original_book with title set to "The Ruby Way" and author set to "Hal Fulton".

Ruby

# Define the Book class and create original_book instance
# Your code here

Need a hint?

Use attr_accessor for title and author. Initialize instance variables in initialize. Create original_book with given values.

2

Create copies using dup and clone

Create two new variables: dup_book by calling original_book.dup and clone_book by calling original_book.clone.

Ruby

class Book
  attr_accessor :title, :author

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

original_book = Book.new("The Ruby Way", "Hal Fulton")
# Create dup_book and clone_book from original_book
# Your code here

Need a hint?

Use dup and clone methods on original_book to create copies.

3

Modify the copies' attributes

Change the title of dup_book to "The Ruby Way - Dup" and the title of clone_book to "The Ruby Way - Clone".

Ruby

class Book
  attr_accessor :title, :author

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

original_book = Book.new("The Ruby Way", "Hal Fulton")
dup_book = original_book.dup
clone_book = original_book.clone
# Change titles of dup_book and clone_book
# Your code here

Need a hint?

Assign new strings to the title attribute of dup_book and clone_book.

4

Print the titles of all books

Print the title of original_book, dup_book, and clone_book each on a new line using puts.

Ruby

class Book
  attr_accessor :title, :author

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

original_book = Book.new("The Ruby Way", "Hal Fulton")
dup_book = original_book.dup
clone_book = original_book.clone
dup_book.title = "The Ruby Way - Dup"
clone_book.title = "The Ruby Way - Clone"
# Print titles of original_book, dup_book, and clone_book
# Your code here

Need a hint?

Use puts to print the title of each book object on separate lines.