OptParse is a module introduced in Python2.3 that makes it easy to write command line tools. See "Option parsing tools" for others.

You give a description of the options that the program can receive, and OptParse will do reasonable stuff for you.

For example:

   1 import optparse
   2 
   3 if __name__=="__main__":
   4     parser = optparse.OptionParser("usage: %prog [options] arg1 arg2")
   5     parser.add_option("-H", "--host", dest="hostname",
   6                       default="127.0.0.1", type="string",
   7                       help="specify hostname to run on")
   8     parser.add_option("-p", "--port", dest="portnum", default=80,
   9                       type="int", help="port number to run on")
  10 
  11     (options, args) = parser.parse_args()
  12     if len(args) != 2:
  13         parser.error("incorrect number of arguments")
  14     hostname = options.hostname
  15     portnum = options.portnum

args contains your fixed arguments, options contains your values.

For example, options.portnum would contain the integer 80, in the example above.

References

• Official Python optparse Documentation

Complaints

• optparse does not support 'required' arguments. The documentation justifies this by saying 'options are optional'. But look at python and its use of keyword arguments. And look at optparse iself! It has the required option 'action'! optparse is a utility! Not a way to enforce a philosphy.

  See this thread in the retired getopt-sig mailing list. I also seem to remember a more protracted discussion about "required" arguments/options. -- David Boddie