Exiting and Exit Codes

Cappa provides an Exit class to allow someone to gracefully exit the program, without emitting a traceback.

import cappa

def function():
    ...
    raise cappa.Exit(message="Oh no!", code=1)
    # or
    raise cappa.Exit("Oh no!", code=1)
    # or
    raise cappa.Exit(code=1)
    # or
    raise cappa.Exit("Graceful exit")  # i.e. status code 0!

@cappa.command(invoke=function)
...

Output and Error Messages

By default, cappa.parse or cappa.invoke will internally construct an Output object which controls, among other things, how Exit messages are handled. Both functions accept an output argument, allowing you to control an Output’s settings.

Of note, there are two message templates:

• output_format (default {message}): Exit code == 0

• error_format (default {short_help}\n\n[red]Error[/red]: {message}): Exit code != 0

If, for example, you did not want to include short_help by default, and wanted “Error” to be orange, you could do as follows:

output = cappa.Output(error_format="[orange]Error[/orange]: {message}")
cappa.parse(Command, output=output)