Is it possible to make an option in optparse a mandatory?

Question

Is it possible to make an option in optparse a mandatory?

Execratory

Yes, it is possible. Check out the answer to this question here (stackoverflow.com/questions/4407539) – Yeryerevan

Yes, but you shouldn't do that, because that's against convention and standard of command line interface. There is a reason, why options can't be made mandatory. Read the optparse docs, it is stated there clearly. – Aleman

Ok, then why is that argparse allows for required options? To quote, argparse docs: Optparse refuses to support these features, preferring purity over practicality. – Yeryerevan

I believe you have answered your own question :-) I am using argparse, because I like positional argument functionality, but I keep to command line standards. – Aleman

I understand the point you are trying to make, but there is a difference between 'not possible' and 'should be avoided.' – Yeryerevan

Besides the fact that the optparse module is deprecated, making an option mandatory seems like an oxymoron... – Ferocious

Answer 1

I posted a comment earlier, but given that many other answers say No, not possible, here is how to do it:

parser = OptionParser(usage='usage: %prog [options] arguments')
parser.add_option('-f', '--file', 
                        dest='filename',
                        help='foo help')
(options, args) = parser.parse_args()
if options.filename is None:   # if filename is not given
    parser.error('Filename not given')

This makes the -f as mandatory.

Using argparse is an alternative indeed, but that doesn't mean you can't do this in optparse also.

Yeryerevan

Okay, this is what I meant by ( - optparse set it to some default like None and check for not None), I think should have provided an example. Thanks. BTW, this is not done by optparse, you are doing it by checking for the option's value in the program. – Sarmentum

Indeed, optparse has no role, this is just a way to make an option required. – Yeryerevan

Answer 2

option is by defeinition optional :-) If you need to make something mandatory, use argparse and set a positional argument.

http://docs.python.org/dev/library/argparse.html

Aleman

You can install argparse separately. code.google.com/p/argparse Then, when you upgrade python, you can migrate painlessly. – Aleman

Answer 3

No, you can't. Either you can use argparse and or you get the option value from using the optparse module and explicitly check if the optionvalue is defined (like in the optparse set it to some default like None and check for not None) and if it is not defined, call sys.exit() asking the users to provide that option.

Sarmentum