Python Exception Handling 3

Question 1

What is the purpose of the `raise ... from ...` syntax introduced in Python 3?

Accepted Answer

To chain exceptions and explicitly set the cause

Answer

`raise NewException() from original` explicitly chains exceptions, setting `__cause__` so the traceback shows the causal relationship.

Question 2

Which attribute stores the exception that caused another exception when using implicit exception chaining?

Accepted Answer

__context__

Answer

`__context__` is set automatically when an exception is raised while another exception is already being handled (implicit chaining).

Question 3

What does `raise ValueError('bad input') from None` do?

Accepted Answer

Suppresses the exception chain, hiding the original cause

Answer

Using `from None` suppresses the exception chain so the original exception context is not displayed in the traceback.

Question 4

How can a custom exception class pass additional data to the handler?

Accepted Answer

By overriding __init__ to store extra attributes

Answer

Override `__init__` in your custom exception to accept and store extra attributes that handlers can access via the exception object.

Question 5

What is the base class for all non-system-exiting exceptions in Python?

Accepted Answer

Exception

Answer

`Exception` is the base class for all regular (non-system-exiting) exceptions; catching it excludes `SystemExit`, `KeyboardInterrupt`, etc.

Python Practice Test