public function savePreviousVersion($version)
    {
        if (!is_numeric($version)) {
            return;
        }

        try {
            $this->setVersionNumber($version);
            $this->owner->write();
        } catch (Exception $e) {
            throw new ValidationException(new ValidationResult(
                false,
                "Could not replace file #{$this->owner->ID} with version #$version."
            ));
        }
    }