How to change the topic_name string to PROGMEM in rosserial_arduino?

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Hello,

I'm trying to save SRAM on my Arduino pro mini by going through some libraries. I've noticed that to use my Arduino as a ROS node the library stores the topic name and message type as constants.

class Publisher
{
public:
  Publisher( const char * topic_name, Msg * msg, int    endpoint=rosserial_msgs::TopicInfo::ID_PUBLISHER) :
    topic_(topic_name), 
    msg_(msg),
    endpoint_(endpoint) {};

  int publish( const Msg * msg ) { return nh_->publish(id_, msg); };
  int getEndpointType(){ return endpoint_; }

  const char * topic_;
  Msg *msg_;
  // id_ and no_ are set by NodeHandle when we advertise 
  int id_;
  NodeHandleBase_* nh_;

private:
  int endpoint_;
};

How can I store the constants to PROGMEM? As these are pointers, I am confused. Thank you.