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How to read message from ros::MessageEvent object

asked 2012-12-13 03:55:40 -0600

Subhash gravatar image

updated 2014-01-28 17:14:33 -0600

ngrennan gravatar image

I am trying to extract content of the message from ros::MessageEvent object.

The parameter ros::MessageEvent<topic_tools::shapeshifter const=""> msg_event is passed to subscription callback function. We know the message type and definition. How can we extract the content of message from ShapeShifter object?

I am trying to do this. But I am stuck about how extract the information further. boost::shared_ptr<topic_tools::shapeshifter const=""> pose = msg_event.getMessage();

Thanks

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Unfortunately, you failed to provide some information which makes it hard to be helpful. Please provide real code and the actual error messages you get. Additionally, always provide your Ubuntu version and the ROS version you are using. Read http://ros.org/wiki/Support

Lorenz gravatar image Lorenz  ( 2012-12-16 21:45:43 -0600 )edit

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answered 2012-12-16 21:52:47 -0600

Lorenz gravatar image

updated 2012-12-16 21:53:33 -0600

I don't know how your code exactly looks like or what exactly you are trying to do but in order to instantiate a real message from a shape shifter message, you need to know its type and and you need to include the corresponding header files. For instance, to instantiate a geometry_msgs::Pose message:

#include <geometry_msgs/Pose.h>

void pose_subscriber(const boost::shared_ptr<const topic_tools::ShapeShifter> message) {
  boost::shared_ptr<geometry_msgs::Pose> pose = message.instantiate<geometry_msgs::Pose>();
  // Do stuff...
}

// The subscriber somewhere in your code...
ros::Subscriber subscriber = node_handle.subscribe<topic_tools::ShapeShifter>("pose_topic", 1, &pose_subscriber);
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Asked: 2012-12-13 03:55:40 -0600

Seen: 1,108 times

Last updated: Dec 16 '12