[Node Arguments] Python nodes support parameters

[sloretz]

Python nodes in Crystal support parameters
ros2 param list requires fully qualified node name (ros2/ros2cli#178)

[wjwwood]

lgtm

[nuclearsandwich]

Does the fully qualified name work in bouncy?

[sloretz]

Does the fully qualified name work in bouncy?

Oops, it does not

Bouncy

$ ros2 run demo_nodes_cpp talker __params:=demo_params.yaml > /dev/null &
[1] 1308
$ ros2 param list talker
  a_string
  some_int
  some_lists.some_doubles
  some_lists.some_integers
$ ros2 param list /talker
Node not found

command does not work in bouncy

[nuclearsandwich]

In that case we probably want to split out and describe both somehow.

Perhaps something like

In bouncy, the name is not fully qualified.

ros2 param list talker

It's awkward, but I was trying to keep Crystal+ the default.

[nuclearsandwich]

While I'm thinking about bouncy, should the C++ caveat line that was removed instead be changed to

Parameters support for Python nodes was added in Crystal. In Bouncy and earlier only C++ nodes are supported.

[sloretz]

@nuclearsandwich how does it look now?

[nuclearsandwich]

Thanks for iterating. Apologies for the confusion of approving first and asking questions after.

[nuclearsandwich]

We should revisit these changes now that ros2/ros2cli#179 has made the leading / optional across ros2cli verbs, including parameters ones.

[sloretz]

We should revisit these changes now that ros2/ros2cli#179 has made the leading / optional across ros2cli verbs, including parameters ones.

@nuclearsandwich I confirmed ros2 param list talker works with latest crystal debs, and undid the changes to that part of the document.

[nuclearsandwich]

Thanks again for the continued iteration.