Problem with nodehandle before ros::init

Question

Hi

I have inserted a shortened version of my files below, but first i'll try to explain my problem. My problem is that I want to define a MoveTo() function within skills.cpp, which uses actionlib client acUR5. I can't define the MoveTo() function without defining acUr5 before the definition of the MoveTo() function in skills.cpp. The acUr5 needs ros::init(), which first have been defined in the main() function. Thus then I run execute_actionlib_client.cpp. I get the error showed in the bottom of this post.

execute_actionlib_client.cpp:

#include <ros/ros.h>
#include <actionlib/client/simple_action_client.h>
#include <actionlib/client/terminal_state.h>
#include <rq3_proxy/rq3Action.h>
#include <ur5_proxy/ur5Action.h>
#include "skills/skills.hpp"

int main (int argc, char **argv){

ros::init(argc, argv, "skills_node");

actionlib::SimpleActionClient<rq3_proxy::rq3Action> acRq3("rq3proxynode", true);
actionlib::SimpleActionClient<ur5_proxy::ur5Action> acUr5("ur5Node", true);

rq3_proxy::rq3Goal goalRq3;
ur5_proxy::ur5Goal goalUr5;

MoveTo();

Skills.cpp:

#include <ros/ros.h>
#include <actionlib/client/simple_action_client.h>
#include <actionlib/client/terminal_state.h>
#include <rq3_proxy/rq3Action.h>
#include <ur5_proxy/ur5Action.h>

#include "skills.hpp"

actionlib::SimpleActionClient<rq3_proxy::rq3Action> acRq3("rq3proxynode", true);
actionlib::SimpleActionClient<ur5_proxy::ur5Action> acUr5("ur5Node", true); // PROBLEM

rq3_proxy::rq3Goal goalRq3;
ur5_proxy::ur5Goal goalUr5;

void MoveTo(){
    //Viapoint, becore place
    acUr5.sendGoalAndWait(move("j", "car", 60,-508, 212, 1.7574, 0.7509, 1.714, 2, 0, 0, goalUr5),ros::Duration(30.0),ros::Duration(30.0));
    ROS_INFO("Viapoint 2 finished");
}

Problem when run:

private@pc:~/ros_ws/devel_ws$ rosrun skills execute_actionlib_client 
[FATAL] [1384343030.296120354]: You must call ros::init() before creating the first NodeHandle
[FATAL] [1384343030.296325757]: BREAKPOINT HIT
    file = /tmp/buildd/ros-groovy-roscpp-1.9.50-0precise-20131015-2117/src/libros/node_handle.cpp
    line=151

Trace/breakpoint trap (core dumped)

I hope you understand the problem and that you can help

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Originally posted by mortenpj on ROS Answers with karma: 70 on 2013-11-13

Post score: 1

Answer 1

The two ActionClients in skills.cpp are attempting to create NodeHandle objects within their internal implementation: https://github.com/ros/actionlib/blob/hydro-devel/include/actionlib/client/action_client.h#L184

In the ROS C++ API (roscpp), you must always call ros::init before creating a NodeHandle.

As those are global variables, they are constructed before main() is even run. You must delay the construction of these objects until after main() has executed. The easiest way is to make the global variables pointers, create a function which sets those global variables, and then call that function after main() has started.

actionlib::SimpleActionClient<rq3_proxy::rq3Action>* acRq3;
actionlib::SimpleActionClient<ur5_proxy::ur5Action>* acUr5;

void initActionClients()
{
  acRq3 = new actionlib::SimpleActionClient("rq3proxynode", true);
  acUr5 = new actionlib::SimpleActionClient("acUr5", true);
}

int main()
{
  ros::init(argc, argv);
  initActionClients();
  //Be happy
}

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Originally posted by mirzashah with karma: 1209 on 2013-11-13

This answer was ACCEPTED on the original site

Post score: 4

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Original comments

Comment by mortenpj on 2013-11-13:
Thanks for your answer! I made it work with a few corrections to your suggestion. I added the type to acRq3 and acUr5 in the function. Changed acUr5.sendGoalAndWait to acUr5->sendGoalAndWait. And I have passed an argument to the function MoveTo(acUr5).

Comment by mirzashah on 2013-11-13:
ah yes i forgot the template type parameters...didn't actually test it. and yes the "->" are required for pointer types