publisher and rosinit

asked 2011-09-28 07:50:40 -0500

kang
79 ●12 ●14 ●18

Hi,

I have a small coding problem while writing publisher. Usually I write publisher inside main function in my code:

pub.publish(data);

after initialize ros, create nodhandle, and define publisher. Similar like this tutorial).

Now, I trying to publish not in my main function. But this could not work since the ros initialization and nodeHandle etc are in main function. And if I write the nodehandle in my one of my subfunction, the nodehandle will also directly off after the subfunction being called.

I was thinking if the rosinit could be initialized before the main function, but still have found the way.

Let me now if someone have suggestion. Thx

Cheers, Kang

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answered 2011-09-28 11:28:45 -0500

KoenBuys
2314 ●21 ●35 ●56 http://people.mech.kul...

You want the publisher to be declared as a global object. You create the node handle in your start up routine/constructor and initialise the publisher from that.

 //globally defined
 ros::Publisher pub_;

 //in your constructor
 int main(int argc, char** argv){
 ...
 pub_ = nh_.advertise<PointCloud> ("points2", 1);
 ...
 }

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answered 2011-09-29 19:24:47 -0500

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

If you don't like global variables, you can also pass the publisher by reference to a function:

void worker (ros::Publisher& pub)
{
  //...
}

int main (int argc, char** argv)
{
  //...
  ros::NodeHandle nh;
  ros::Publisher pub = nh.advertise<PointCloud>("points2", 1);
  //...
  worker(pub);
  //...
}

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3

answered 2011-09-28 08:07:31 -0500

Dan Lazewatsky
9115 ●79 ●103 ●160 http://dan.lazewatsky.com/

Make the node handle a global or class variable so you can reference it from anywhere. You can declare the node handle, without initializing it, then do the initialization in your main function.

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the nodeHandle can be set globlally? I think I have tried that one, but I'll check again soon.

kang ( 2011-09-28 08:09:05 -0500 )edit

creating nodeHandle before ros initialization is not allowed. But, I made it work by defining variable in a class.

kang ( 2011-09-28 19:26:12 -0500 )edit

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