When parsing command line options, I found very useful
to have an
option with a facultative value, able to do the following:

1-tell to me if the option was or was not seen on the
command line, return the value None if the option was
not seen;

2-if the option only was specified, return a default value.

3-if the option with a value was specified on the
command line, return the specified value;

A way to reach this goal can be the addition of a new
value for the options actions in module optparse, it
may be something like "store_with_default".

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I don't know what "facultative" means, but what you want is
optional option arguments.  Don't worry, I want that feature
too, and have even started implementing it on a branch of
the Optik source repository.  See
http://sourceforge.net/tracker/?func=detail&aid=1050431&group_id=38019&atid=421100
for a similar feature request.

I'm leaving this open, since I haven't finished anything or
merged it into the Python CVS.  It could be a few months
before there's any action here, and it certainly won't
happen before Optik 1.6 / Python 2.5.  Might require Optik
2.0, in which case I'm not certain when it'll get into Python.

Greg, since optik is maintained separately, it seems to make sense to close this and possibly create a new report in optik.  http://sourceforge.net/projects/optik .  Let me know if that's not how you want to handle bugs/feature requests.