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Hey, Kind of newbie in using boost, and this is driving me crazy. I wanted to pass on the topicname to the callback function of subscriber, so I followed the various questions already asked and wrote the following: My callback function:

void write_enocean(const palgate_madynes_msg::EnOceanFrame& msg,std::string topic)

Subscriber:

sub[i] = nh.subscribe(Topiclist[i].name,1000,boost::bind(&write_enocean,_1,Topicname[i].name));

If I do this, I get the following error:

error: no matching function for call to ‘ros::NodeHandle::subscribe(std::string&, int, boost::_bi::bind_t<void, void (*)(const palgate_madynes_msg::EnOceanFrame_<std::allocator<void> >&, std::basic_string<char>), boost::_bi::list2<boost::arg<1>, boost::_bi::value<std::basic_string<char> > > >*)’

followed by the various candidates, and then:

node_handle.h:785:14: note:   candidate expects 1 argument, 3 provided

On the other hand, if write the subscriber as such:

 sub[i] = nh.subscribe<palgate_madynes_msg::EnOceanFrame>(Topiclist[i].name,1000,boost::bind(&write_enocean,_1,test));

I get the error:

/usr/include/boost/bind/bind.hpp:313:9: error: invalid initialization of reference of type ‘const palgate_madynes_msg::EnOceanFrame_<std::allocator<void> >&’ from expression of type ‘const boost::shared_ptr<const palgate_madynes_msg::EnOceanFrame_<std::allocator<void> > >’

What am I doing wrong with boost? My CMakeLists.text already includes the rosbuild_add_boost_directories() but gives me an error if write rosbuild_link_boost(topic_listener bind) saying it could not locate bind.

Originally posted by Mandar on ROS Answers with karma: 73 on 2014-01-23

Post score: 3

Original comments

Comment by dornhege on 2014-01-24:
It seems to have problems to pick the right overload. Does it help to move the bind into a boost::function.

Comment by Mandar on 2014-01-24:
I'm not sure I understand what you mean. Do I use it something like boost::function(bind, ...) or? I've not really used boost before, hence the confusion.

Comment by dornhege on 2014-01-24:
You can put the return of a bind in a boost::function and give that a specific function type. When playing around with bind and callbacks that helps to isolate the problem.

Comment by luc on 2015-10-05:
Might be missing a _1 as the third arg.

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2 Answers 2

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I would not mess with boost::bind in this case and put the callback function in a class in order for passing the context to it. Example:

class MySubscriber
{
  std::string po_topic_name;
  ros::Subscriber po_sub;

  void write_enocean( const palgate_madynes_msg::EnOceanFrame& msg )
  {
    // use po_topic_name as you like ...
  }
public:
  
  MySubscriber( ros::NodeHandle ao_nh, std::string ao_topic ) :
    po_topic_name( ao_topic )
  {
    po_sub = ao_nh.subscribe( ao_topic,1000, &MySubscriber::write_enocean, this );
  }
};

Now you just have to create an Instance of MySubscriber for each of your topics...

Originally posted by Wolf with karma: 7555 on 2014-01-24

This answer was ACCEPTED on the original site

Post score: 4

Original comments

Comment by Mandar on 2014-01-24:
I'll try this out and report back in case of errors. Thanks!

Comment by Mandar on 2014-01-24:
I modified the example code you provided to follow the tutorial http://wiki.ros.org/roscpp_tutorials/Tutorials/UsingClassMethodsAsCallbacks more closely. This way, only the function write_enocean and the topic_name were in the class, while the subscriber was defined outside, rather than class method

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You are using the wrong signature in your callback. Replace

void write_enocean(const palgate_madynes_msg::EnOceanFrame& msg,std::string topic)

with

void write_enocean(const palgate_madynes_msg::EnOceanFrame::ConstPtr& msg,std::string topic)

Originally posted by roehling with karma: 1951 on 2014-01-24

This answer was NOT ACCEPTED on the original site

Post score: 2

Original comments

Comment by Mandar on 2014-01-24:
Wow, that was simple to fix. I wonder which method would be better to use - this answer or using classes as suggested by @Wolf.

Comment by roehling on 2014-01-26:
How you design your classes is up to you. However, I recommend the ConstPtr variant in all cases, because passing shared pointers allows ROS to bypass serialization and use shared memory message transport in nodelets.

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