Why isn't fromfile-prefix-chars in Python argparse working?

Question

I\'m trying to use the fromfile-prefix-chars feature of argparse in Python to load all my command line arguments from a file, but it keeps complaining that I haven\'t specif

Answer 1

I think there's a better answer to this: use shlex.

if sys.argv[1].startswith('@'):
    args = parser.parse_args( shlex.split(open(sys.argv[1][1:]).read()) )
else:
    args = parser.parse_args()

This allows you to specify args in a file in a more natural way e.g., it allows using spaces or equals sign to specify your args on a single line as in:

arg1
arg2
--opt1 'foo'
--opt2='bar'

shlex.split splits this as you would expect:

['arg1', 'arg2', '--opt1', 'foo', '--opt2=bar']

The only thing this method doesn't have is that it expects the @file.txt to be the first argument.