Adapt to '--ros-args ... [--]'-based ROS args extraction (#405)

* Use --ros-args in args related tests.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Prepend Node CLI args with --ros-args flags.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Document implicit --ros-args flag in Node CLI args.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

* Only add implicit --ros-args flag if not present already.

Signed-off-by: Michel Hidalgo <michel@ekumenlabs.com>

rclpy/rclpy/__init__.py

@@ -121,7 +121,8 @@ def create_node(
     :param node_name: A name to give to the node.
     :param context: The context to associated with the node, or ``None`` for the default global
         context.
-    :param cli_args: Command line arguments to be used by the node.
+    :param cli_args: Command line arguments to be used by the node. Being specific to a ROS node,
+        an implicit `--ros-args` scope flag always precedes these arguments.
     :param namespace: The namespace prefix to apply to entities associated with the node
         (node name, topics, etc).
     :param use_global_arguments: ``False`` if the node should ignore process-wide command line

rclpy/rclpy/node.py

@@ -115,6 +115,8 @@ def __init__(
         :param context: The context to be associated with, or ``None`` for the default global
             context.
         :param cli_args: A list of strings of command line args to be used only by this node.
+            Being specific to a ROS node, an implicit `--ros-args` scope flag always precedes
+            these arguments.
         :param namespace: The namespace to which relative topic and service names will be prefixed.
             Validated by :func:`validate_namespace`.
         :param use_global_arguments: ``False`` if the node should ignore process-wide command line
@@ -144,12 +146,15 @@ def __init__(
         self._parameter_overrides = {}
         self._descriptors = {}
 
+        if cli_args is not None and '--ros-args' not in cli_args:
+            cli_args = ['--ros-args', *cli_args]
         namespace = namespace or ''
         if not self._context.ok():
             raise NotInitializedException('cannot create node')
         try:
             self.__handle = Handle(_rclpy.rclpy_create_node(
-                node_name, namespace, self._context.handle, cli_args, use_global_arguments))
+                node_name, namespace, self._context.handle, cli_args, use_global_arguments
+            ))
         except ValueError:
             # these will raise more specific errors if the name or namespace is bad
             validate_node_name(node_name)

rclpy/test/test_node.py

@@ -1529,7 +1529,10 @@ class TestCreateNode(unittest.TestCase):
 
     def test_use_global_arguments(self):
         context = rclpy.context.Context()
-        rclpy.init(args=['process_name', '__node:=global_node_name'], context=context)
+        rclpy.init(
+            args=['process_name', '--ros-args', '__node:=global_node_name'],
+            context=context
+        )
         try:
             node1 = rclpy.create_node(
                 'my_node', namespace='/my_ns', use_global_arguments=True, context=context)

rclpy/test/test_utilities.py

@@ -21,7 +21,16 @@
 class TestValidateRemoveRosArgs(unittest.TestCase):
 
     def test_remove_ros_args(self):
-        args = ['process_name', '-d', '__ns:=/foo/bar', '__ns:=/fiz/buz', '--foo=bar', '--baz']
+        args = [
+            'process_name',
+            '-d',
+            '--ros-args',
+            '__ns:=/foo/bar',
+            '__ns:=/fiz/buz',
+            '--',
+            '--foo=bar',
+            '--baz'
+        ]
         stripped_args = rclpy.utilities.remove_ros_args(args=args)
         self.assertEqual(4, len(stripped_args))
         self.assertEqual('process_name', stripped_args[0])