The Python command line parameter parsing module optparse USES instances

The sample

from optparse import OptionParser

[...]

def main():

    usage = "usage: %prog [options] arg"

    parser = OptionParser(usage)

    parser.add_option("-f", "--file", dest="filename",

                      help="read data from FILENAME")

    parser.add_option("-v", "--verbose",

                      action="store_true", dest="verbose")

    parser.add_option("-q", "--quiet",

                      action="store_false", dest="verbose")

    [...]

    (options, args) = parser.parse_args()

    if len(args) != 1:

        parser.error("incorrect number of arguments")

    if options.verbose:

        print "reading %s..." % options.filename

    [...]
if __name__ == "__main__":

    main()

Add options (add_option())

OptionParser.add_option(option)

OptionParser.add_option(*opt_str, attr=value, ...)

Define short options

parser.add_option( " -f " , attr=value,  ... )

Define long options

parser.add_option( "� foo " , attr=value,  ... )

If you define

​parser.add_option("-f", "--file", action="store", type="string", dest="filename")

The command line format can take the following forms

-ffoo

-f foo

--file=foo

--file foo

Parsed result

options.filename =  " foo " 

Resolution (parse_args ())

(options, args) = parser.parse_args()

Parameters parsed by options are saved in dictionary form
Parameters that args cannot parse are saved as a list

Behavior (action)

●store default behavior, save the value to dest
● "store_const" holds the constant
● "append" append this option's argument to a list
● "count" increment a counter by one
● "callback" call a specified function

Set the default value (default)

parser.add_option("-v", action="store_true", dest="verbose", default=True)

parser.set_defaults(verbose=True)

Generate help tips (help)

Just provide the help option and you can print it out with parser.print_help ()

parser.add_option( " -f " ,  "� file " , dest= " filename " ,help= " write report to FILE " , metavar= " FILE " )

Setting boolean value

store_true and store_false are supported

parser.add_option("-v", action="store_true", dest="verbose")

parser.add_option("-q", action="store_false", dest="verbose")

If you encounter -v,verbose=True; If you encounter -q,verbose=False

Error handling

(options, args) = parser.parse_args()

[...]

if options.a and options.b:

    parser.error("options -a and -b are mutually exclusive")

Option group (Grouping Options)

Format is as follows

class optparse.OptionGroup(parser, title, description=None)

group = OptionGroup(parser, "Dangerous Options",

                    "Caution: use these options at your own risk.  "

                    "It is believed that some of them bite.")

group.add_option("-g", action="store_true", help="Group option.")

parser.add_option_group(group)

The results are as follows

Usage: <yourscript> [options] arg1 arg2
Options:

  -h, --help            show this help message and exit

  -v, --verbose         make lots of noise [default]

  -q, --quiet           be vewwy quiet (I'm hunting wabbits)

  -f FILE, --filename=FILE

                        write output to FILE

  -m MODE, --mode=MODE  interaction mode: novice, intermediate, or

                        expert [default: intermediate]
  Dangerous Options:

    Caution: use these options at your own risk.  It is believed that some

    of them bite.
    -g                  Group option.