filterROSArgs function in init.cpp

[Karsten1987]

Allows a pre-filtering of ROS keywords before calling ros::init().

This is an alternative to ros::this_node::getName() [0], since this requires to call ros::init(argc, argv, "node_name") beforehand and forcing to specify a node name.
ros::filterROSArgs can be called wo/ init for filter various keywords such as __name or __ns.

$ rosrun hello_world hello_world __name:=foo

// hello_world.cpp
int main( int argc, char** argv )
{ 
  std::string node_name = ros::filterROSArgs(argc, argv, "__name");
  if (!node_name.empty())
    ros::init(argc, argv, node_name);
  else
    ros::init(argc, argv, "bar");

  return 0;
}

In case the desired argument is not found, an empty string is returned.

[ros-pull-request-builder]

Can one of the admins verify this patch?

[wjwwood]

I guess you'll be using this for some other ROS parameter or in some other way? The reason I ask is that this code is equivalent to your snippet above:

// hello_world.cpp
int main( int argc, char** argv )
{ 
  ros::init(argc, argv, "bar");

  return 0;
}

If you run it without a __name:= argument it will be called bar, but if you call it with __name:=foo it will be called foo.

[dirk-thomas]

Can you please describe your use case?

Beside that I am not sure if filterROSArgs is a suitable name for the function. Since it doesn't really filter anything and only checks for one specific argument I would suggest calling it getROSArg instead.

[Karsten1987]

@wjwwood I might be wrong here, but ros::this_node::getName() resolves the complete namespace. So the example you gave would lead to /foo. Launching the executable inside a namespace bar_ns would return /bar_ns/foo as a name. Can you confirm that?

Initial motivation comes from this PR ros-naoqi/naoqi_driver#44.
Other use cases are launching the same executable for different devices (e.g. IP cameras) and adjusting their unique topic/rosparam names on runtime via a respective launch file.

In general I was wondering how you'd access the __name variable anyways which is passed by a launch file when inside your ros::init you overwrite this by a hard-coded name?

@dirk-thomas Sure, there is no problem in renaming this. You guys might find better names according to the context.

[dirk-thomas]

@Karsten1987 Can you please update the function according to my previous comment.

[dirk-thomas]

@ros-pull-request-builder

[ros-pull-request-builder]

Test passed.
Refer to this link for build results: http://jenkins.ros.org/job/_pull_request-indigo-ros_comm/431/

[dirk-thomas]

Thanks for iterating on this. Next time please also comment on the ticket since there is no notification for pushing to a PR.