## create parser
import cmdopt
parser = cmdopt.Parser()
## define options
parser.option("-h, --help",      "show help")
parser.option("-f, --file=FILE", "read file")
## parse args
import sys
args = sys.argv[1:]
defaults = {'file': "config.json"}
try:
    opts = parser.parse(args, defaults)
    print(opts)
except cmdopt.ParseError as ex:
    sys.stderr.write("%s\n" % ex)
    sys.exit(1)

## no argument
parser.option("-h",         "show help")
parser.option("    --help", "show help")
parser.option("-h, --help", "show help")
## required argument
parser.option("-f FILE",         "read file")
parser.option("    --file=FILE", "read file")
parser.option("-f, --file=FILE", "read file")
## optional argument
parser.option("-i[N]",            "indent width")
parser.option("    --indent[=N]", "indent width")
parser.option("-i, --indent[=N]", "indent width")

parser.option("-m, --mode=MODE", "set mode")\
      .validation(lambda val: val not in ['verbose', 'quiet']
                              and "'verbose' or 'quiet' expected.")
parser.option("-i, --indent[=N]", "indent width (default 2)")\
      .validation(lambda val: val != True and not val.isdigit()
                              and "integer required.")

## change default handler
parser.option("--verbose", "quiet mode")\
      .action(lambda val, opts: setattr(opts, 'mode', "verbose"))
parser.option("--quiet", "quiet mode")\
      .action(lambda val, opts: setattr(opts, 'mode', "quiet"))

## The following definitions...
parser.option("-h, --help",      "show help")
parser.option("-f, --file=FILE", "read file")
## are equivarent to:
parser.option("-h, --help",      "show help")\
      .action(lambda val, opts: setattr(opts, 'help', val))
parser.option("-f, --file=FILE", "read file")\
      .action(lambda val, opts: setattr(opts, 'file', val))

## define custom handler to store values into list
def add_path(val, opts):
    arr = getattr(opts, 'paths', None)
    if arr is None:
        opts.paths = []
    opts.paths.append(val)
parser.option("-I path  #paths", "include path (multiple OK)")\
      .action(add_path)
##
opts = parser.parse(["-Ipath1", "-Ipath2", "-Ipath3"])
assert opts.paths == ["path1", "path2", "path3"]

## usually, long name or sort name is used as attribute name of opts.
parser.option("-h, --help", "show help")
opts = parser.parse(["-h"])
assert opts.help == True    # attr name == long name
parser.option("-h", "show help")
opts = parser.parse(["-h"])
assert opts.h == True       # attr name == short name
## it is possible to specify attribute name by '#name'.
## this is very helpful when you want not to use long name.
parser.option("-h  #help", "show help")
opts = parser.parse(["-h"])
assert opts.help == True    # not opts.h

print("Usage: command [options] [file...]")
print(parser.help())    # or parser.help(20, "  ")

parser.option("-D, --debug", None)   # private option: no description
helpmsg = parser.help()
assert '--debug' not in helpmsg      # not included in help message