Remove Redundant Exception

Sourcery refactoring id: remove-redundant-exception

Description

Remove redundant exceptions from an except clause.

Before

try:
    int("not an int")
except (ValueError, Exception):
    logger.log("error")

After

try:
    int("not an int")
except Exception:
    logger.log("error")

Explanation

An except clause handles all instances of the defined exception, incl. its subclasses. If an exception is a subclass of another exception, it’s redundant to mention both explicitly in the except clause.

Note that:

• All built-in, non-system-exiting exceptions are derived from the Exception class.
• All user-defined exceptions should also be derived from the Exception class.
• It’s a good practice to have a base exception class for your application (deriving from Exception) and have your more specific custom exceptions derive from it.

Related Rules

• merge-except-handler to merge except handlers with the same content
• remove-redundant-except-handler to remove unreachable except blocks
• use-contextlib-suppress instead of empty except blocks
• do-not-use-bare-except to always specify which errors an except block is handling