import optparse

class Option (optparse.Option):
   ATTRS = optparse.Option.ATTRS + ['required']

   def _check_required (self):
       if self.required and not self.takes_value():
           raise OptionError(
               "required flag set for option that doesn't take a value",
                self)

   # Make sure _check_required() is called from the constructor!
   CHECK_METHODS = optparse.Option.CHECK_METHODS + [_check_required]

   def process (self, opt, value, values, parser):
       optparse.Option.process(self, opt, value, values, parser)
       parser.option_seen[self] = 1


class OptionParser (optparse.OptionParser):

   def _init_parsing_state (self):
       optparse.OptionParser._init_parsing_state(self)
       self.option_seen = {}

   def check_values (self, values, args):
       for option in self.option_list:
           if (isinstance(option, Option) and
               option.required and
               not self.option_seen.has_key(option)):
               self.error("%s not supplied" % option)
       return (values, args)


parser = OptionParser(option_list=[
   Option("-v", action="count", dest="verbose"),
   Option("-f", "--file", required=1)])
(options, args) = parser.parse_args()

print "verbose:", options.verbose
print "file:", options.file