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pythonpython-2.7argparsedocopt

How can I collect two options each with multiple arguments in Python's argparse module?

I want to parse two long command line options - a list of files and a command like so:

python example.py file1 file2 -- echo hello world

With a result of: 

>>> args.filenames
["file1", "file2"]
>>> args.command
["echo", "hello", "world"]

Is this possible in argparse or any other python CLI library (such as docopt)?

Solution

  • In argparse, the -- means, treat everything that follows as positional strings. But all strings in your sample look like that, so the -- does nothing. So the remaining question is, how is argparse suppose to to allocate the 5 strings to 2 arguments. nargs=2, and narg='*' would do the trick if you always want 2 'files'. + and REMAINDER (...) would also work for the 2nd.

    What won't work is * followed by *. That would be akin to a RegEx pattern of '(a*)(a*)'. In fact argparse uses RegEx pattern matching to allocate strings to positional arguments. Creating the 2 arguments, and trying various nargs values can be instructive.

    Another option is to replace the -- with an optionals argument, e.g. -c with a nargs='*'.