'Pass an empty list to `argv` to avoid reading `sys.argv` (the
default).
Set components first (`self.set_reader` & `self.set_writer`).'

def process_command_line(self, argv=None, usage=None, description=None, settings_spec=None, config_section=None, **defaults):

    option_parser = self.setup_option_parser(usage, description, settings_spec, config_section, **defaults)
    if (argv is None):
        argv = sys.argv[1:]
    self.settings = option_parser.parse_args(argv)
