opster 2.0

command line parsing speedster

Opster is a command line options parser, intended to make writing command line applications easy and painless. It uses built-in Python types (lists, dictionaries, etc) to define options, which makes configuration clear and concise. Additionally it contains possibility to handle subcommands (i.e. hg commit or svn update).

Quick example

That’s an example of an option definition:

import sys
from opster import command

@command(usage='%name [-n] MESSAGE')
def main(message,
         no_newline=('n', False, 'don\'t print a newline')):
    'Simple echo program'
    sys.stdout.write(message)
    if not no_newline:
        sys.stdout.write('\n')

if __name__ == '__main__':
    main()

Running this program will print the help:

echo.py [-n] MESSAGE

Simple echo program

options:

 -n --no-newline  don't print a newline
 -h --help        show help

As you can see, here we have defined option to not print newline: keyword argument name is a long name for option, default value is a 3-tuple, containing short name for an option (can be empty), default value (on base of which processing is applied - see description) and a help string.

Underscores in long names are converted into dashes.

If you are calling a command with option using long name, you can supply it partially. In this case it could look like ./echo.py --nonew. This is also true for subcommands: read about them and everything else you’d like to know in documentation.

Plans

• Better documentation

• (under consideration) ability to have few command collectors in a single application (more than one dispatching entry point)

Changelog

2.0 (2010.01.23)

• fix help display when there is no __doc__ declared for function

• dict type handling

• .help() attribute for every function, printing help on call

1.2 (2010.12.29)

• fix option display for a list of subcommands if docstring starts with a blank line

1.1 (2010.12.07)

• _completion was failing to work when global options were supplied to command dispatcher

1.0 (2010.12.06)

• when middleware was used and command called without arguments, instead of help, traceback was displayed

0.9.13 (2010.11.18)

• fixed exception handling (cleanup previous fix, actually)

• display only name of application, without full path

0.9.12 (2010.11.02)

• fixed trouble with non-ascii characters in docstrings

0.9.11 (2010.09.19)

• fixed exceptions handling

• autocompletion improvements (skips middleware, ability of options completion)

0.9.10 (2010.04.10)

• if default value of an option is a fuction, always call it (None is passed in case when option is not supplied)

• always call a function if it’s default argument for an option

• some cleanup with better support for python 3

• initial support for autocompletion (borrowed from PIP)

0.9 - 0.9.9 (since 2009.07.13)

Ancient history ;-)