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.verboseprint "file:", options.file