listener_with_tracked_object.cpp

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/*
 * Copyright (C) 2008, Morgan Quigley and Willow Garage, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the names of Stanford University or Willow Garage, Inc. nor the names of its
 *     contributors may be used to endorse or promote products derived from
 *     this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "ros/ros.h"
#include "std_msgs/String.h"

#include <boost/shared_ptr.hpp>

class Object
{
public:
  void chatterCallback(const std_msgs::String::ConstPtr& msg)
  {
    ROS_INFO("This should never be printed: [%s]", msg->data.c_str());
  }
};
typedef boost::shared_ptr<Object> ObjectPtr;

void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
  ROS_INFO("Only this version should print: [%s]", msg->data.c_str());
}

int main(int argc, char **argv)
{
  ros::init(argc, argv, "listener");
  ros::NodeHandle n;

  ObjectPtr obj(new Object);
  ros::Subscriber sub = n.subscribe("chatter", 1, &Object::chatterCallback, obj);
  ros::Subscriber sub2 = n.subscribe("chatter", 1, chatterCallback);

  // Delete the object.
  // Because we've passed in the object to be tracked as a shared pointer,
  // this is safe.  The callback inside the Object class should never get called,
  // because its pointer is no longer valid.
  obj.reset();

  ros::spin();

  return 0;
}