Parameters not set from the command-line using new syntax

[jacobperron]

Bug report

Required Info:

• Operating System:
  • Ubuntu 18.04
• Installation type:
  • source
• Version or commit hash:
  • b6d18cc
• DDS implementation:
  • N/A
• Client library (if applicable):
  • rclcpp

Steps to reproduce issue

Create a simple node that echos a parameter:

#include <iostream>
#include <memory>

#include "rclcpp/rclcpp.hpp"

class FooNode : public rclcpp::Node
{
public:
  explicit FooNode(const rclcpp::NodeOptions options = rclcpp::NodeOptions())
  : Node("foo_node", options)
  { 
    auto param_value = this->declare_parameter("foo", "bar");
    std::cout << "param value: " << param_value << std::endl;
  }
};

int main(int argc, char** argv)
{
  rclcpp::init(argc, argv);

  auto node = std::make_shared<FooNode>();

  rclcpp::spin(node);

  return 0;
}

Run the node and try to set the parameter "foo":

./foo --ros-args -p foo:=jacob

Expected behavior

The node prints the value set from the command line:

param value: jacob

Actual behavior

The node prints the default value:

param value: bar

Additional information

Passing the parameter via a YAML file works fine, e.g

params.yaml

foo_node:
  ros__parameters:
    foo: "jacob"

and running

./foo --ros-args --params-file params.yaml

[jacobperron]

@hidmic FYI

[hidmic]

Alright, it looks like in between changes to rcl and how the command line looks like, the last round of changes was left forgotten in my local clones of rclcpp and rclpy. Which also means things are not being tested properly. My bad. I'll clean it up, add tests and send it.

[jacobperron]

I'll clean it up, add tests and send it.

🙇‍♂️

[jacobperron]

@hidmic Looks like this was fixed? Though I don't know by what changes exactly.

[hidmic]

Yes it was! By ros2/rcl#508 and #865. Closing.

[hamaney]

I see this issue in rclpy.
I don't know how to check the version/branch I am on, but I installed ros2 using
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
sudo sh -c 'echo "deb [arch=amd64,arm64] http://packages.ros.org/ros2/ubuntu lsb_release -cs main" > /etc/apt/sources.list.d/ros2-latest.list'

the question seems to be related
https://answers.ros.org/question/348149/confision-about-ros2-rclpy-parameter/?answer=348191#post-id-348191

[jacobperron]

@hamaney If you installed ROS 2 with apt, then the major version should be name of the package(s) you install (e.g. ros-dashing-desktop). Furthermore, it should also appear in the path of the setup file you source (e.g. source /opt/ros/dashing/setup.bash). If you are still not sure which version of ROS 2 you have installed, you can try echoing the environment variable ROS_DISTRO (e.g. on Linux: echo $ROS_DISTRO).

As pointed out on ROS answers, this method for passing ROS parameters is only supported since ROS 2 Eloquent. So if you are using ROS 2 Dashing, it will not work. If you continue to have problems, please comment on ROS Answers (or create a new question) with details about your installation. This lets other users benefit from the answer. (GitHub tickets are not as visible)

[hamaney]

Sorry, my mistake. I know the distro of ROS2 that I am using, which is Dashing as you mentioned.
I was under the impression that ROS2 versioning is the destro name and number. That's why I asked how to find more info about what I am running. Thanks for your help.

[jacobperron]

@hamaney No worries. Because ROS follows a federated model for packages, each package has a version number, but ROS distro as a whole just has a name (e.g. Dashing). If you want to know the particular version of a package, you can use the following ros2pkg command:

# Get the version of rclcpp
ros2 pkg xml rclcpp --tag version