Exception hierarchy in Python - Mini Project: Build & Apply

Exception hierarchy

📖 Scenario: Imagine you are building a simple program that handles different types of errors when processing user input. You want to organize these errors in a clear way using Python's exception hierarchy.

🎯 Goal: You will create a base exception class and two specific exception classes that inherit from it. Then you will write code to raise and catch these exceptions properly.

📋 What You'll Learn

Create a base exception class called InputError that inherits from Exception.

Create two exception classes called ValueTooSmallError and ValueTooLargeError that inherit from InputError.

Write code to raise ValueTooSmallError if a number is less than 10.

Write code to raise ValueTooLargeError if a number is greater than 100.

Use a try-except block to catch these exceptions and print a message.

💡 Why This Matters

🌍 Real World

Organizing errors in a program helps keep code clean and makes it easier to find and fix problems.

💼 Career

Understanding exception hierarchy is important for writing robust software that handles errors gracefully in professional development.

1

Create the base exception class

Create a class called InputError that inherits from Exception.

Python

# Your code here

Need a hint?

Use class InputError(Exception): and add pass inside.

2

Create specific exception classes

Create two classes called ValueTooSmallError and ValueTooLargeError that both inherit from InputError.

Python

class InputError(Exception):
    pass

# Your code here

Need a hint?

Define each class with class ClassName(InputError): and add pass inside.

3

Raise exceptions based on number value

Create a variable called number and set it to 5. Then write code to raise ValueTooSmallError if number is less than 10, and raise ValueTooLargeError if number is greater than 100.

Python

class InputError(Exception):
    pass

class ValueTooSmallError(InputError):
    pass

class ValueTooLargeError(InputError):
    pass

number = 5
# Your code here

Need a hint?

Use if number < 10: and raise ValueTooSmallError("message"). Use elif number > 100: and raise ValueTooLargeError("message").

4

Catch and handle the exceptions

Use a try-except block to catch ValueTooSmallError and ValueTooLargeError. Print "Caught too small error" if ValueTooSmallError is caught, and print "Caught too large error" if ValueTooLargeError is caught.

Python

class InputError(Exception):
    pass

class ValueTooSmallError(InputError):
    pass

class ValueTooLargeError(InputError):
    pass

number = 5
try:
    if number  100:
        raise ValueTooLargeError("The value is too large")
except ValueTooSmallError:
    # Your code here
except ValueTooLargeError:
    # Your code here

Need a hint?

Use try: block around the code that raises exceptions. Use except ValueTooSmallError: and except ValueTooLargeError: to catch and print messages.