Question

Why won’t argparse parse these arguments?

--foo 1 2 3 bar

Using

parser = argparse.ArgumentParser()
parser.add_argument('--foo', nargs='+')                  
parser.add_argument('bar')

which gives the following error:

error: too few arguments

If I pass the bar argument first though, it works:

bar --foo 1 2 3   

Now, this in itself is not too bad. I can live with having the positional arguments first it’s just that this behaviour is inconsistent with the help argparse creates for us, which states that bar should be last:

usage: argparsetest.py [-h] [–foo FOO
[FOO …]] bar

So how do you make this work with consistent help text?

Here’s a complete test program.

Answer 1

Maybe try doing –input –output flags and setting those options to required=True in the add_argument?

http://docs.python.org/dev/library/argparse.html#the-add-argument-method