Exception hierarchy in Ruby - Mini Project: Build & Apply

Exception hierarchy

📖 Scenario: Imagine you are building a simple program that handles different types of errors. You want to organize these errors in a clear way so your program can respond properly when something goes wrong.

🎯 Goal: You will create a small exception hierarchy with a base error class and two specific error classes. Then, you will raise and rescue these errors to see how the hierarchy works.

📋 What You'll Learn

Create a base exception class called MyAppError that inherits from StandardError.

Create two subclasses called DatabaseError and NetworkError that inherit from MyAppError.

Write code to raise a DatabaseError exception.

Write code to rescue the exception using the base class MyAppError and print a message.

💡 Why This Matters

🌍 Real World

Organizing errors in a clear hierarchy helps large programs handle problems gracefully and makes debugging easier.

💼 Career

Understanding exception hierarchies is important for writing robust software and is a common skill required in software development jobs.

1

Create the base exception class

Create a class called MyAppError that inherits from StandardError.

Ruby

# Your code here

Need a hint?

Use class MyAppError < StandardError to create the base exception class.

2

Create subclasses for specific errors

Create two classes called DatabaseError and NetworkError that inherit from MyAppError.

Ruby

class MyAppError < StandardError
end

# Your code here

Need a hint?

Define each subclass with class ClassName < MyAppError.

3

Raise a DatabaseError exception

Write code to raise a DatabaseError exception with the message "Database connection failed".

Ruby

class MyAppError < StandardError
end

class DatabaseError < MyAppError
end

class NetworkError < MyAppError
end

# Your code here

Need a hint?

Use raise DatabaseError, "Database connection failed" to raise the exception.

4

Rescue the exception and print a message

Wrap the code that raises the DatabaseError inside a begin block. Rescue the exception using MyAppError and print "Caught an error: " followed by the exception message.

Ruby

class MyAppError  e
  # Your code here
end

Need a hint?

Use begin and rescue MyAppError => e to catch the error and puts to print the message.