Subclass with < operator in Ruby - Mini Project: Build & Apply

Subclass with < operator

📖 Scenario: Imagine you are creating a simple system to compare different types of boxes by their volume. You want to be able to say if one box is smaller than another using the &lt; operator.

🎯 Goal: You will create a subclass called Box that inherits from a class Container. You will add the &lt; operator to compare boxes by their volume.

📋 What You'll Learn

Create a class called Container with attributes length, width, and height.

Create a subclass called Box that inherits from Container.

Add a method <(other) in Box to compare volumes of two boxes.

Create two Box objects with given dimensions.

Print the result of comparing the two boxes using the < operator.

💡 Why This Matters

🌍 Real World

Comparing sizes of physical objects like boxes is common in shipping and storage to optimize space.

💼 Career

Understanding subclassing and operator overloading is useful for designing clear and reusable code in software development.

1

Create the Container class with dimensions

Create a class called Container with an initialize method that takes length, width, and height as parameters and sets them as instance variables.

Ruby

# Define class Container with initialize method
# Your code here

Need a hint?

Use def initialize(length, width, height) and set instance variables with @length = length, etc.

2

Create the Box subclass inheriting from Container

Create a subclass called Box that inherits from Container. Add an initialize method in Box that calls super with length, width, and height.

Ruby

class Container
  def initialize(length, width, height)
    @length = length
    @width = width
    @height = height
  end
end

# Define subclass Box inheriting from Container
# Your code here

Need a hint?

Use class Box < Container and call super(length, width, height) inside initialize.

3

Add the < operator method to compare volumes

In the Box class, add a method def <(other) that returns true if the volume of the current box is less than the volume of other. Calculate volume as @length * @width * @height.

Ruby

class Container
  def initialize(length, width, height)
    @length = length
    @width = width
    @height = height
  end
end

class Box < Container
  def initialize(length, width, height)
    super(length, width, height)
  end

  # Define < operator to compare volumes
  # Your code here
end

Need a hint?

Use def <(other) and compare volumes using instance variables. Use other.instance_variable_get(:@length) to access other's dimensions.

4

Create two Box objects and print comparison result

Create two Box objects called box1 with dimensions 2, 3, 4 and box2 with dimensions 3, 3, 3. Then print the result of box1 < box2.

Ruby

class Container
  def initialize(length, width, height)
    @length = length
    @width = width
    @height = height
  end
end

class Box < Container
  def initialize(length, width, height)
    super(length, width, height)
  end

  def <(other)
    (@length * @width * @height) < (other.instance_variable_get(:@length) * other.instance_variable_get(:@width) * other.instance_variable_get(:@height))
  end
end

# Create box1 and box2 with given dimensions
# Print the result of box1 < box2
# Your code here

Need a hint?

Create box1 and box2 with Box.new and print box1 < box2.