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bare-except (E722)

Added in v0.0.36 · Related issues · View source

Derived from the pycodestyle linter.

What it does

Checks for bare except catches in try-except statements.

Why is this bad?

A bare except catches BaseException which includes KeyboardInterrupt, SystemExit, Exception, and others. Catching BaseException can make it hard to interrupt the program (e.g., with Ctrl-C) and can disguise other problems.

Example

try:
    raise KeyboardInterrupt("You probably don't mean to break CTRL-C.")
except:
    print("But a bare `except` will ignore keyboard interrupts.")

Use instead:

try:
    do_something_that_might_break()
except MoreSpecificException as e:
    handle_error(e)

If you actually need to catch an unknown error, use Exception which will catch regular program errors but not important system exceptions.

def run_a_function(some_other_fn):
    try:
        some_other_fn()
    except Exception as e:
        print(f"How exceptional! {e}")

References