Support choices lists for YAML launch arguments

launch_yaml/launch_yaml/entity.py

@@ -113,16 +113,32 @@ def get_attr(
         `launch_yaml` does not apply type coercion,
         it only checks if the read value is of the correct type.
         """
-        if name not in self.__element:
+        attribute_name = name
+        if (
+            self.type_name == 'arg' and
+            name == 'choice' and
+            name not in self.__element and
+            'choices' in self.__element
+        ):
+            attribute_name = 'choices'
+        if attribute_name not in self.__element:
             if not optional:
                 raise AttributeError(
                     "Can not find attribute '{}' in Entity '{}'".format(
                         name, self.type_name))
             else:
                 return None
-        self.__read_keys.add(name)
-        data = self.__element[name]
+        self.__read_keys.add(attribute_name)
+        data = self.__element[attribute_name]
         if check_is_list_entity(data_type):
+            if attribute_name != name:
+                if is_instance_of(data, List[str], can_be_str=False):
+                    return [Entity({'value': value}, name) for value in data]
+                raise TypeError(
+                    "Attribute '{}' of Entity '{}' expected to be a list of strings.".format(
+                        attribute_name, self.type_name
+                    )
+                )
             if isinstance(data, list) and isinstance(data[0], dict):
                 return [Entity(child, name) for child in data]
             raise TypeError(

launch_yaml/test/launch_yaml/test_arg.py

@@ -0,0 +1,93 @@
+# Copyright 2026 Old-Ding
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test parsing a launch argument."""
+
+import io
+import textwrap
+
+from launch.actions import DeclareLaunchArgument
+
+from parser_no_extensions import load_no_extensions
+
+import pytest
+
+
+def test_arg_choices():
+    yaml_file = textwrap.dedent(
+        """
+        launch:
+            - arg:
+                name: ur_type
+                default: ur5e
+                choices: [ur3, ur3e, ur5e]
+        """
+    )
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+    launch_description = parser.parse_description(root_entity)
+
+    argument = launch_description.entities[0]
+    assert isinstance(argument, DeclareLaunchArgument)
+    assert argument.choices == ['ur3', 'ur3e', 'ur5e']
+
+
+def test_arg_legacy_choices():
+    yaml_file = textwrap.dedent(
+        """
+        launch:
+            - arg:
+                name: ur_type
+                choice:
+                    - value: ur3
+                    - value: ur3e
+        """
+    )
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+    launch_description = parser.parse_description(root_entity)
+
+    argument = launch_description.entities[0]
+    assert isinstance(argument, DeclareLaunchArgument)
+    assert argument.choices == ['ur3', 'ur3e']
+
+
+def test_arg_choices_reject_non_string_values():
+    yaml_file = textwrap.dedent(
+        """
+        launch:
+            - arg:
+                name: ur_type
+                choices: [ur3, 5]
+        """
+    )
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+
+    with pytest.raises(TypeError, match="'choices'.*list of strings"):
+        parser.parse_description(root_entity)
+
+
+def test_arg_choices_reject_legacy_and_shorthand_together():
+    yaml_file = textwrap.dedent(
+        """
+        launch:
+            - arg:
+                name: ur_type
+                choice:
+                    - value: ur3
+                choices: [ur3e]
+        """
+    )
+    root_entity, parser = load_no_extensions(io.StringIO(yaml_file))
+
+    with pytest.raises(ValueError, match="Unexpected key.*'choices'"):
+        parser.parse_description(root_entity)