optparse - required options

Robert Dailey rcdailey at gmail.com
Mon Aug 20 22:53:12 CEST 2007

Well, I don't know what is wrong with people then. I don't see how required
arguments are of bad design. Some command-line applications are built around
performing tasks based on information received. Compilers, for example. A
compiler can't do much of anything unless you give it at the very least a
filename. So, a --file command would most definitely be one required
argument. Anyway, I'm not trying to start a debate on this issue. I have my
own implementation for required arguments at the moment, I am just a little
bit surprised that this module doesn't make it convenient. It would
definitely help on code duplication.

Thanks for your response.

On 8/20/07, Jay Loden <python at jayloden.com> wrote:
> Robert Dailey wrote:
> > Hi,
> >
> > I've been reading through the python documentation on the optparse
> > module and I was unable to find out how to specify if an option is
> > optional or required. The documentation vaguely states that actions can
> > be used to do this, however I was not able to figure out how. If anyone
> > could help I'd greatly appreciate it.
> >
> According to the optparse docs:
> required option
>     an option that must be supplied on the command-line; note that the
>     phrase ``required option'' is self-contradictory in English. optparse
>     doesn't prevent you from implementing required options, but doesn't
>     give you much help at it either. See examples/required_1.py and
>     examples/required_2.py in the optparse source distribution for two
>     ways to implement required options with optparse.
> And from what I can see, this seems to be somewhat intentional, see
> http://wiki.python.org/moin/OptParse the note at the bottom with a link to
> a mailing list thread. As far as I can tell, evidently some people feel that
> required options are indicative of a bad design and therefore optparse was
> designed not to make this easy on the programmer.
> -Jay
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