Hello!

I am looking for a way to separate parameters in certain node to several groups, in a way similar to ROS1 functionality.

Defining the parameters in YAML file allows nesting parameters in subgroups, and these groups can be defined using dot in parameter names, e.g: node.declare_parameter("group_a.param_b")

I have created the example node to demonstrate the issue. https://gist.github.com/yossioo/c20d2966c9e27e57a3153d9ec176e896

I can see the declared parameters:

$ ros2 param list
/node_w_params:
  group_a.param_b
  group_a.param_c
  param_a
  use_sim_time

Checking the list of parameters shows that the prefixes are indeed recognized by ROS2:

$ ros2 service call /node_w_params/list_parameters rcl_interfaces/srv/ListParameters 
waiting for service to become available...
requester: making request: rcl_interfaces.srv.ListParameters_Request(prefixes=[], depth=0)

response:
rcl_interfaces.srv.ListParameters_Response(result=rcl_interfaces.msg.ListParametersResult(names=['use_sim_time', 'param_a', 'group_a.param_b', 'group_a.param_c'], prefixes=['group_a']))

And yet, the parameters are not grouped in the rqt_reconfigure interface and are simply presented in a single alphabetically ordered list.

Is there a proper way to define parameters so they will be displayed in groups?