Hello,
I'm trying to use argparse in a program that gets some options and
positional arguments. I want to collect all the positional arguments
in a single argument using the REMAINDER option to add_argument() as
shown bellow:
parser = argparse.ArgumentParser(description='Test argparse')
parser.add_argument('-v', '--verbose', action='store_true')
parser.add_argument('cmd_args', nargs=argparse.REMAINDER)
print parser.parse_args()
This works well unless the first positional argument starts with a
'-'.
For example, with the above code
my_prog -v hello world
works well, but
my_prog -v -x hello world
Fails with an error message 'error: unrecognized arguments: -x'.
If I invoke the program with a '--' at the end of the options (as I
understand is a common standard and a POSIX recommendation), as in:
my_prog -v -- -x hello world
It works well again.
However, a few questions remain:
Firstly, as far as I can tell the use of '--' is not documented in the
argparse documentation (but the code of argparse clearly shows that it
is a feature).
Secondly, when using '--', this string itself is inserted into the
list of the collected positional arguments (in the above example in
the cmd_args variable):
$ ./my_prog -v -- -x hello world
Namespace(cmd_args=['--', '-x', 'hello', 'world'], verbose=True)
It's quiet easy to check for it and remove it if it exists, but it
still seems like it shouldn't be there - it is not really an argument,
just a delimiter.
Am I doing anything wrong, or is this a bug? I hope someone here can
shed some light on this.
Thanks,
Amit
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