Raising exceptions

What is Raising an Exception?

Raising an exception allows you to create errors intentionally in your code. This is useful for signaling that something has gone wrong and should be handled.

The raise Statement

You can use the raise statement to trigger an exception explicitly.

raise Exception("This is an error message.")

Raising Built-in Exceptions

You can raise built-in exceptions like ValueError, TypeError, etc., to indicate specific errors.

def divide(a, b):
    if b == 0:
        raise ZeroDivisionError("Division by zero is not allowed.")
    return a / b

Custom Messages

Providing custom error messages helps make exceptions more informative.

def process_data(data):
    if not isinstance(data, list):
        raise TypeError("Data should be a list.")

Raising Custom Exceptions

Creating custom exceptions can make your code more readable and specific to your application.

class CustomError(Exception):
    pass

def check_value(value):
    if value < 0:
        raise CustomError("Value must be non-negative.")

Using raise with Exception Chaining

You can use raise to re-raise exceptions, preserving the original traceback for better debugging.

try:
    # Code that might cause an exception
    pass
except SomeError as e:
    raise AnotherError("Additional context") from e

Conclusion

Raising exceptions helps in enforcing correct behavior and makes debugging easier by providing meaningful error messages.