Instance_variable_get and set in Ruby - Mini Project: Build & Apply

Using instance_variable_get and instance_variable_set in Ruby

📖 Scenario: Imagine you have a simple Ruby class representing a book. You want to access and change the book's title and author dynamically using special Ruby methods.

🎯 Goal: Learn how to use instance_variable_get and instance_variable_set to read and update instance variables of an object.

📋 What You'll Learn

Create a class Book with instance variables @title and @author

Create an object of class Book with specific title and author

Use instance_variable_get to read the @title variable

Use instance_variable_set to change the @author variable

Print the updated author name

💡 Why This Matters

🌍 Real World

Sometimes you need to access or change object data dynamically when you don't know the variable names in advance, like in debugging tools or meta-programming.

💼 Career

Understanding how to manipulate instance variables dynamically helps in advanced Ruby programming, frameworks, and libraries that use meta-programming.

1

Create the Book class with instance variables

Define a class called Book with an initialize method that sets instance variables @title and @author using parameters title and author. Then create an object called my_book with title "Ruby Basics" and author "Alice".

Ruby

# Define class Book with initialize method
# Create my_book with title "Ruby Basics" and author "Alice"
# Your code here

Need a hint?

Use def initialize(title, author) and set @title and @author inside it. Then create my_book with Book.new.

2

Read the @title instance variable using instance_variable_get

Use instance_variable_get on my_book to read the value of the @title instance variable and store it in a variable called book_title.

Ruby

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

my_book = Book.new("Ruby Basics", "Alice")

# Use instance_variable_get to read @title into book_title
# Your code here

Need a hint?

Call my_book.instance_variable_get(:@title) and assign it to book_title.

3

Change the @author instance variable using instance_variable_set

Use instance_variable_set on my_book to change the @author instance variable to "Bob".

Ruby

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

my_book = Book.new("Ruby Basics", "Alice")

book_title = my_book.instance_variable_get(:@title)

# Use instance_variable_set to change @author to "Bob"
# Your code here

Need a hint?

Call my_book.instance_variable_set(:@author, "Bob") to update the author.

4

Print the updated author name

Use instance_variable_get on my_book to get the updated @author and print it.

Ruby

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

my_book = Book.new("Ruby Basics", "Alice")

book_title = my_book.instance_variable_get(:@title)

my_book.instance_variable_set(:@author, "Bob")

# Print the updated author
# Your code here

Need a hint?

Use puts my_book.instance_variable_get(:@author) to print the new author.