Creating exception classes in Python - Quick Revision & Summary

Recall & Review

beginner

What is the purpose of creating custom exception classes in Python?

Custom exception classes help you handle specific errors in your program clearly and separately from built-in exceptions. They make your code easier to understand and debug.

beginner

How do you define a simple custom exception class in Python?

You create a new class that inherits from the built-in <code>Exception</code> class. For example:<br><pre>class MyError(Exception):
    pass</pre>

intermediate

Why might you add an __init__ method to a custom exception class?

To accept and store extra information about the error, like a message or error code, which you can use later when handling or displaying the error.

intermediate

What is the benefit of overriding the __str__ method in a custom exception?

It lets you control the error message shown when the exception is printed or converted to a string, making error messages clearer and more helpful.

beginner

Can custom exceptions be caught using a general except Exception: block?

Yes, because custom exceptions inherit from Exception, they can be caught by a general exception handler, but catching them specifically is better for precise error handling.

Which class should a custom exception usually inherit from?

A Exception

B object

C BaseException

D Error

Custom exceptions typically inherit from Exception to be caught by standard error handling.

What keyword is used to create a new exception class in Python?

A def

B class

C exception

D raise

You use the class keyword to define a new exception class.

What does the pass statement do inside a custom exception class?

A Handles the exception

B Raises the exception

C Imports a module

D Defines an empty class body

pass means the class has no extra code or behavior.

Why override the __str__ method in a custom exception?

A To change how the exception is printed

B To stop the exception from being raised

C To inherit from Exception

D To catch the exception

Overriding __str__ customizes the error message shown.

Which statement raises a custom exception named MyError?

A throw MyError()

B raise new MyError()

C raise MyError()

D throw new MyError()

In Python, raise is used to throw exceptions.

Explain how to create a custom exception class and why it is useful.

Think about how you want to catch and describe special errors in your program.

Describe how you can add extra information to a custom exception and show it when the error is printed.

Consider how to pass and display details about the error.