title: ROS: Use lambda as callback in nodehandle.subscribe
body: <p>I want to be able to define a callback through a lambda but I can't get any of the function signatures to match. </p>
  
  <pre><code>std::function&lt;void(const sensor_msgs::PointCloud2)&gt; callback = 
   [&amp;mycapture](const sensor_msgs::PointCloud2 msg) { 
   // do something with msg and capture
   };
  
  auto sub = ros_node.subscribe("/sometopic", 1, callback)
  </code></pre>
  
  <p>I can't get this to work as subscribe wants a function pointer. Is what I'm trying to do possible with ROS? That is, can I pass into the subscribe method a lambda with a capture?</p>