boost::bind errors in subscriber callback functions

asked 2014-01-23 21:56:59 -0600

Mandar
73 ●3 ●6 ●12

updated 2014-01-28 17:19:09 -0600

ngrennan
1 ●1 ●1

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.

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It seems to have problems to pick the right overload. Does it help to move the bind into a boost::function.

dornhege ( 2014-01-24 00:27:42 -0600 )edit

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.

Mandar ( 2014-01-24 01:01:29 -0600 )edit

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.

dornhege ( 2014-01-24 01:19:25 -0600 )edit

Might be missing a _1 as the third arg.

luc ( 2015-10-05 00:03:49 -0600 )edit

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answered 2014-01-23 23:29:16 -0600

Wolf

7555 ●71 ●105 ●162

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...

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I'll try this out and report back in case of errors. Thanks!

Mandar ( 2014-01-24 00:30:13 -0600 )edit

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

Mandar ( 2014-01-24 01:34:20 -0600 )edit

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answered 2014-01-24 01:34:16 -0600

roehling
1951 ●25 ●28 ●43 http://www.fkie.fraunhofer.de/

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)

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Wow, that was simple to fix. I wonder which method would be better to use - this answer or using classes as suggested by @Wolf.

Mandar ( 2014-01-24 02:39:45 -0600 )edit

2

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.

roehling ( 2014-01-26 22:38:35 -0600 )edit

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boost::bind errors in subscriber callback functions

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