base.py 文件源码

def get_active_version(self):
        if self._active is not None:
            return self.supported[self._active]
        key = getattr(settings, self.SETTINGS_KEY, {}).get(self.service_type)
        if key is None:
            # TODO(gabriel): support API version discovery here; we'll leave
            # the setting in as a way of overriding the latest available
            # version.
            key = self.preferred
        # Since we do a key lookup in the supported dict the type matters,
        # let's ensure people know if they use a string when the key isn't.
        if isinstance(key, six.string_types):
            msg = ('The version "%s" specified for the %s service should be '
                   'either an integer or a float, not a string.' %
                   (key, self.service_type))
            raise exceptions.ConfigurationError(msg)
        # Provide a helpful error message if the specified version isn't in the
        # supported list.
        if key not in self.supported:
            choices = ", ".join(str(k) for k in six.iterkeys(self.supported))
            msg = ('%s is not a supported API version for the %s service, '
                   ' choices are: %s' % (key, self.service_type, choices))
            raise exceptions.ConfigurationError(msg)
        self._active = key
        return self.supported[self._active]