Inherited hook in Ruby - Mini Project: Build & Apply

Using the Inherited Hook in Ruby

📖 Scenario: Imagine you are creating a system to track different types of vehicles. You want to know whenever a new type of vehicle class is created that inherits from your main Vehicle class.

🎯 Goal: You will build a Ruby program that uses the inherited hook method to print a message every time a new subclass inherits from Vehicle.

📋 What You'll Learn

Create a class called Vehicle

Define an inherited method inside Vehicle that takes one argument called subclass

Inside the inherited method, print a message using puts that says: "New vehicle type created: "

Create two subclasses called Car and Truck that inherit from Vehicle

Print the messages when Car and Truck are defined

💡 Why This Matters

🌍 Real World

Using the <code>inherited</code> hook helps frameworks and libraries track subclasses automatically, such as in web frameworks or plugin systems.

💼 Career

Understanding hooks like <code>inherited</code> is useful for Ruby developers building extensible applications or working with metaprogramming.

1

Create the Vehicle class

Create a class called Vehicle with no content inside it.

Ruby

# Create a class called Vehicle
# Your code here

Need a hint?

Use class Vehicle and end to define the class.

2

Add the inherited hook method

Inside the Vehicle class, define a method called self.inherited that takes one parameter called subclass. Inside this method, use puts to print "New vehicle type created: " followed by the subclass name using subclass.name.

Ruby

class Vehicle
  # Define the inherited hook method here
  # Your code here
end

Need a hint?

The inherited method is a class method, so use self.inherited.

3

Create subclasses Car and Truck

Create two subclasses called Car and Truck that inherit from Vehicle. Use the syntax class Car < Vehicle and class Truck < Vehicle.

Ruby

class Vehicle
  def self.inherited(subclass)
    puts "New vehicle type created: #{subclass.name}"
  end
end

# Create subclass Car
# Your code here

# Create subclass Truck
# Your code here

Need a hint?

Use class Car < Vehicle and class Truck < Vehicle to create subclasses.

4

Run the program to see output

Run the program and observe the output. It should print two lines: "New vehicle type created: Car" and "New vehicle type created: Truck".

Ruby

class Vehicle
  def self.inherited(subclass)
    puts "New vehicle type created: #{subclass.name}"
  end
end

class Car < Vehicle
end

class Truck < Vehicle
end

# Run the program to see output
# Your code here

Need a hint?

Just run the program. The messages print automatically when subclasses are defined.