[Python-Dev] Command line options for features in stdlib WAS: Pronouncement on PEP 389: argparse?

Olemis Lang olemis at gmail.com
Tue Dec 15 17:46:44 CET 2009

/me starting a new thread because this goes beyond argparse itself

On Tue, Dec 15, 2009 at 4:34 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Steven Bethard <steven.bethard <at> gmail.com> writes:
>> Because people are continuing this discussion, I'll say again that
>> argparse already supports this:
> Well I think the point is that if there is a default, the default should be
> sensible and not run against expectations.


> It would probably be fine not to have a default at all, too.


I really think that it's good to expect the same (similar) behavior
when the same options is accepted by multiple commands. In the end
that's a decision of the people implementing the concrete command line
tool, but it is nice to rely on something like : «if you forgot, or
don't remember or don't know about it then the std decision is

Now that you mention all this , I follow up with a comment that is
more about -v switch . Most of the time I realize that command line
apps have logging capabilities and should also allow different
verbosity levels (e.g. -q, -s, -v, --noisy) . The good thing is that
this always can be done the same way (i.e. using log levels defined in
logging module ) . The not so good news is that (in practice) coders
have to do it over and over every time they create a new command line
app, and users might need to remember those switches if the author
used different names . My suggestion is that it would be nice to
identify std switches and add support for configuring the cmd-line
parser and logger instance OOTB

import argparse
import logging

if __name__ == ’__main__’:
    # create the parser
    parser = argparse.ArgumentParser(description=’XXX’)
    # add the arguments
    # add args for verbosity level
    # parse the command line
    args = parser.parse_args()
    # configure logging --
    # probably omitted if an option handles this
    # setup the logger instance
    logging.argparseConfig(getLogger('xxx'), args)

The same reasoning could probably be extended to other modules in
stdlib (e.g. default encoding, testing, ...). It's probably a good
idea to define a set of (std) command line args for std features
(preferently without conflicting with existing standards ;o) and
provide shortcuts to ease configuration process when building command
line tools

PS: This thread might also be related to the previous one about
logging configuration using dicts



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