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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).


Requires at least Python 2.6

Quick example

That's an example of an option definition:

import sys
from opster import command

def main(message,
         no_newline=('n', False, "don't print a newline")):
    '''Simple echo program'''
    if not no_newline:

if __name__ == '__main__':

Running this program will print help message:

> ./ invalid arguments [OPTIONS] MESSAGE

Simple echo program


 -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 of options 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 ./ --no-new. This is also true for subcommands: read about them and everything else you'd like to know in documentation.