def get_field(self, schema):
        """Get the requested type definition from the schema and return the
        appropriate :class:`~eulxml.xmlmap.fields.Field`.

        :param schema: instance of :class:`eulxml.xmlmap.core.XsdSchema`
        :rtype: :class:`eulxml.xmlmap.fields.Field`
        """
        type = schema.get_type(self.schema_type)
        logger.debug('Found schema type %s; base type %s, restricted values %s' % \
                     (self.schema_type, type.base_type(), type.restricted_values))
        kwargs = {}
        if type.restricted_values:
            # field has a restriction with enumerated values - pass as choices to field
            # - empty value at beginning of list for unset value; for required fields,
            #   will force user to select a value, rather than first item being default
            choices = []
            choices.extend(type.restricted_values)
            # restricted values could include a blank
            # if it's there, remove it so we don't get two
            if '' in choices:
                choices.remove('')
            choices.insert(0, '')   # add blank choice at the beginning of the list
            kwargs['choices'] = choices

        # TODO: possibly also useful to look for pattern restrictions

        basetype = type.base_type()
        if basetype == 'string':
            newfield = StringField(self.xpath, required=self.required, **kwargs)
            # copy original creation counter to newly created field
            # to preserve declaration order
            newfield.creation_counter = self.creation_counter
            return newfield
        else:
            raise Exception("basetype %s is not yet supported by SchemaField" % basetype)