The [Capn Proto FAQ](https://capnproto.org/faq.html#how-do-i-make-a-field-required-like-in-protocol-buffers) has a rant about the required field that elucidates (in part) the history behind it. Note also that both Capn Proto and Protocol Buffers 3 still support the notion of optional - Capn Proto via [unions](https://capnproto.org/faq.html#how-do-i-make-a-field-optional) and Protocol Buffers 3 via [OneOf](https://developers.google.com/protocol-buffers/docs/proto3#oneof). --- [Visit Topic](https://discourse.ros.org/t/optional-fields-in-message/991/5) or reply to this email to respond. If you do not want to receive messages from ros-users please use the unsubscribe link below. If you use the one above, you will stop all of ros-users from receiving updates. ______________________________________________________________________________ ros-users mailing list ros-users@lists.ros.org http://lists.ros.org/mailman/listinfo/ros-users Unsubscribe: