问由其他参数隐含的argparse子解析器

EN

# This allows a file name ending with any of the given extensions,
# or allows "file.1" in place of "file.1.jpg"
def jpeg_file(s):
    for ext in ("jpg", "jpeg"):
        if s.endswith(ext) or os.path.exists("%s.%s" % (s, ext)):
            return s
    raise argparse.ArgumentTypeError()

def tiff_file(s):
    # similar to jpeg_file

master_parser = argparse.ArgumentParser()
subparsers = master_parser.add_subparsers()
jpg_to_tiff_parser = subparsers.add_parser('sub')
jpg_to_tiff_parser = parse.add_argument('jpg', type=jpg_file)
jpg_to_tiff_parser = parse.add_argument('tiff', type=tiff_file)

#prog.py
topParser=argparse.ArgumentParser()

subParsers = topParser.add_subparsers(
    title='SubCommands', 
    description='Use "prog.py <subCommand> (-h | --help)" to learn more about each subcommand', 
    help='I can do stuff')

subParser1 = subParsers.add_parser('use1', help="Use1 does one thing")
subParser2 = subParsers.add_parser('use2', help='Use2 does another thing')

subParser1.add_argument(
    '-f','--first-arg-for-use1',
    help="A text file",
    required=True
    )

subParser1.add_argument(
    '-s','--second-arg-for-use1',
    help="An encoding",
    required=True
    )

subParser2.add_argument(
    '-f','--first-arg-for-use2',
    help="An image format",
    required=True
    )

args = topParser.parse_args()
print(args)