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What is the difference between the 'except' and '*except' constructs in Python?

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Answer from AI

except catches exceptions of the specified type(s). *except is not a syntactically correct construct in Python and will result in a syntax error. It probably refers to catching all exceptions without specifying a type.

try:
    # Code that may cause an error
    result = 1 / 0
except ZeroDivisionError:
    # Catches the specific ZeroDivisionError exception
    print("Division by zero.")
except TypeError:
    # Catches the specific TypeError exception
    print("Incorrect data type.")
except Exception as e:
    # Catches any other exception not caught above
    print(f"Another error occurred: {e}")

# Unlike the above, *except is not used
# try:
#     result = 1 / 0
# *except: # SyntaxError
#     print("An error occurred.")

Differences:

  • Specificity: except allows explicitly specifying exception types for handling, making the code more readable and predictable. Catching all exceptions (using except:) can hide potential problems, as it handles any errors uniformly.
  • Handling: When using except <ExceptionType>, you can write specific logic for each error type. Catching all exceptions is usually used for general logging or minimal reaction to errors.
  • PEP 8 Recommendations: PEP 8 recommends explicitly specifying the exception types you expect to handle. Catching all exceptions (except:) should be used cautiously, typically at the end of a chain of except blocks, or when you are absolutely sure of what you are doing.

Using except: (without specifying a type) is equivalent to except BaseException:, which catches almost all possible errors, including KeyboardInterrupt and SystemExit. It is generally preferable to use except Exception: to avoid catching system interrupts.