Customized command line parsing in Python

Question

I'm writing a shell for a project of mine, which by design parses commands that looks like this:

COMMAND_NAME ARG1="Long Value" ARG2=123 [email protected]

My problem is that Python's command line parsing libraries (getopt and optparse) forces me to use '-' or '--' in front of the arguments. This behavior doesn't match my requirements.

Any ideas how can this be solved? Any existing library for this?

Answer 1

You could split them up with shlex.split(), which can handle the quoted values you have, and pretty easily parse this with a very simple regular expression. Or, you can just use regular expressions for both splitting and parsing. Or simply use split().

args = {}
for arg in shlex.split(cmdln_args):
    key, value = arg.split('=', 1)
    args[key] = value

Answer 2

1. Try to follow "Standards for Command Line Interfaces"

2. Convert your arguments (as Thomas suggested) to OptionParser format.

   parser.parse_args(["--"+p if "=" in p else p for p in sys.argv[1:]])
   

If command-line arguments are not in sys.argv or a similar list but in a string then (as ironfroggy suggested) use shlex.split().

parser.parse_args(["--"+p if "=" in p else p for p in shlex.split(argsline)])

Answer 3

A small pythonic variation on Ironforggy's shlex answer:

args = dict( arg.split('=', 1) for arg in shlex.split(cmdln_args) )

oops... - corrected.

thanks, J.F. Sebastian (got to remember those single argument generator expressions).

Answer 4

What about optmatch (http://www.coderazzi.net/python/optmatch/index.htm)? Is not standard, but takes a different approach to options parsing, and it supports any prefix:

OptionMatcher.setMode(optionPrefix='-')