Custom Exception Classes in Python — Proper Inheritance and Message Handling

Quick Answer

The correct choice is to override __init__ to accept a message and call super().__init__(message). This is essential because the built-in Exception class stores any passed message in its args attribute, and its default __str__ method relies on that attribute to display the error text when the exception is caught and printed. Without explicitly calling the parent constructor, your custom exception class would not inherit this message-handling behavior, and the message would be lost or not shown. On the Certified Associate Python Programmer PCAP exam, this tests your understanding of proper inheritance in Python’s exception hierarchy, often appearing as a multiple-choice trap where a candidate might override __str__ instead of __init__. The common mistake is forgetting that the base class already handles string representation, so you only need to ensure the message reaches it. Memory tip: “Init it to pass it”—override __init__ to accept the message, then pass it up with super().__init__().