Hi,

I may be wrong but I think the spirit here would be to create one small inline function for each callback and then call the generic function therein with a specific argument. I have not seen anything which would do exactly what you want, but I'm not sure what would be the advantage of adding an argument to the subscribe call-back.

Alternatively, you could define a generic queue object with a callback, and pass the object to the subscriber:
MagicQueue magicQueue1, magicQueue2;
ros::Subscriber sub = n.subscribe("topic1",100,&MagicQueue::callback,magicQueue1);
ros::Subscriber sub = n.subscribe("topic2",100,&MagicQueue::callback,magicQueue2);

In python, this would be used with the "partial" function, which is basically creating a small lambda function at run-time.

HTH

On 07/04/10 15:10, Peter Müller wrote:

Hi,

I have started using ROS recently and played around with it to see how it fits my needs. So far I could work out everything I needed. I just have one little problem left.

This is regarding the callbacks, which get executed when you subscribe to a topic. Lets assume I subscribe to two (three, four...) topics, and the callback method is always the same. Is there a way to tell, which topic executed the callback method?
For example:
ros::Subscriber sub = n.subscribe("topic1", 100, subCallback);
ros::Subscriber sub1 = n.subscribe("topic2", 100, subCallback);

So when subCallback(..) gets executed I can tell if it came from sub or sub1. Is that possible?

Ideally I would like to add an argument to the subCallback method.
For example:
void chatterCallback(int queue_id, const std_msgs::StringConstPtr& msg)

With queue_id being an int I defined when subscribing. Could I do that with my own boost::bind(...)? If so, how?

I looked over the NodeHandle.subscribe code but I believe there is nothing which works the way I want it to?

Any help is appreciated, thanks.
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