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publisher and rosinit

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

kang gravatar image

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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3 Answers

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

KoenBuys gravatar image

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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5

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

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

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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Comments

the nodeHandle can be set globlally? I think I have tried that one, but I'll check again soon.
kang gravatar image 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 gravatar image kang  ( 2011-09-28 19:26:12 -0500 )edit

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

Seen: 3,290 times

Last updated: Sep 29 '11