A raise statement explicitly signals an exception during Python program execution. It interrupts the normal next-statement flow and sends the exception up the current call chain until a suitable handler catches it; without one, the program terminates or reports an error. section 14.2 section 14.1.2
Use the statement with these practical rules:
- Write `raise exception(args)` to create an exception and throw it upward through the stack. section 14.2.2
- Pass arguments that help explain what happened; many built-in exception classes display a first string argument as their message. section 14.2.2
- Choose a handler with `try` and `except` when the raised condition should be handled locally; `else` and `finally` can organize successful and final processing. section 3.4.7
- Treat exception arguments as class-specific: programmer-defined exception types may expect data other than a text message. section 14.2.2
Raise a custom condition
class EmptyFileError(Exception): pass if line == "": raise EmptyFileError("empty file") The surrounding `except EmptyFileError as error` clause can catch the exception and print its message. This makes a condition detected by application code follow the same handling path as exceptions raised by built-in operations. section 3.4.7
raise exception(args)
Inspect the compact syntax before comparing it with a concrete `IndexError` raised explicitly by code. section 14.2.2
