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The wiki page on the cache wasn't really helpful, but I figured out a few problems in your code.

1. There needs to be an implementation of message_traits::TimeStamp. Have a look here. I guess the reason is that the cache needs to ensure the messages to be ordered. All stamped data types, e.g. geometry_msgs/PoseStamped already implement the time stamp. Either implement the traits for the message type you want to use or use a stamped type.

2. For some reason, the compiler refused to resolve the types correctly in the registerCallback method call. By explicitly constructing a boost::function, I could resolve that.

I basically copied your code and changed the message type to PoseStamped. Here the new code:

#include <ros/ros.h>
#include <message_filters/subscriber.h>
#include <message_filters/cache.h>
#include <geometry_msgs/PoseStamped.h>

void some_function (const geometry_msgs::PoseStamped &i) {
  // do something awesome
}

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

  message_filters::Subscriber<geometry_msgs::PoseStamped> sub(nh, "some_topic", 1);
  message_filters::Cache<geometry_msgs::PoseStamped> cache(sub, 100);

  cache.registerCallback(boost::function<void(const geometry_msgs::PoseStamped &)>(&some_function));

  return ros::spin();
}

The wiki page on the cache wasn't really helpful, but I figured out a few problems in your code.

1. There needs to be an implementation of message_traits::TimeStamp. Have a look here. I guess the reason is that the cache needs to ensure the messages to be ordered. order the messages. All stamped data types, e.g. geometry_msgs/PoseStamped already implement the time stamp. stamp trait. Either implement the traits for the message type you want to use or use a stamped type.

2. For some reason, the compiler refused to resolve the types correctly in the registerCallback method call. By explicitly constructing a boost::function, I could resolve that.

I basically copied your code and changed the message type to PoseStamped. Here the new code:

#include <ros/ros.h>
#include <message_filters/subscriber.h>
#include <message_filters/cache.h>
#include <geometry_msgs/PoseStamped.h>

void some_function (const geometry_msgs::PoseStamped &i) {
  // do something awesome
}

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

  message_filters::Subscriber<geometry_msgs::PoseStamped> sub(nh, "some_topic", 1);
  message_filters::Cache<geometry_msgs::PoseStamped> cache(sub, 100);

  cache.registerCallback(boost::function<void(const geometry_msgs::PoseStamped &)>(&some_function));

  return ros::spin();
}

The wiki page on the cache wasn't really helpful, but I figured out a few problems in your code.

1. There needs to be an implementation of message_traits::TimeStamp. Have a look here. I guess the reason is that the cache needs to order the messages. All stamped data types, e.g. geometry_msgs/PoseStamped already implement the time stamp trait. Either implement the traits for the message type you want to use or use a stamped type.

2. For some reason, the compiler refused refuses to resolve the types correctly in the registerCallback method call. By explicitly constructing a boost::function, boost::function or by using boost::bind, I could resolve that.

I basically copied your code and changed the message type to PoseStamped. Here the new code:

#include <ros/ros.h>
#include <message_filters/subscriber.h>
#include <message_filters/cache.h>
#include <geometry_msgs/PoseStamped.h>

void some_function (const geometry_msgs::PoseStamped geometry_msgs::PoseStamped::ConstPtr &i) {
  // do something awesome
}

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

  message_filters::Subscriber<geometry_msgs::PoseStamped> sub(nh, "some_topic", 1);
  message_filters::Cache<geometry_msgs::PoseStamped> cache(sub, 100);

  cache.registerCallback(boost::function<void(const geometry_msgs::PoseStamped &)>(&some_function));

cache.registerCallback(boost::bind(&some_function, _1));

  ros::spin();
  return ros::spin();
0;
}