I have a callback function defined as onstringmsg(const stdmsgs::String::ConstPtr& msg). I have both stdmsgs::String and a self-defined msg which wraps a stdmsgs::String field. myMsg.msg { stdmsgs/String subField; }

How can I get stdmsgs::String::ConstPtr for subField in the myMsg callback function onmyMsg(const myMsg::ConstPtr& msg) so that I can reuse the function onstringmsg(const std_msgs::String::ConstPtr& msg) with the subField?

Basically, I would like to do

on_myMsg(const myMsg::ConstPtr& msg) {

on_string_msg(msg->subFieldConstPtr); // How to achieve this?

}