Try more action types, clean up exporting, add basic test (#3)

* Fix up dynamic attribute inclusion, adding basic pytest for it
* some more basic tests around entity types

Author: emersonknapp

CMakeLists.txt

@@ -10,6 +10,9 @@ ament_python_install_package(${PROJECT_NAME})
 if(BUILD_TESTING)
   find_package(ament_lint_auto REQUIRED)
   ament_lint_auto_find_test_dependencies()
+
+  find_package(ament_cmake_pytest REQUIRED)
+  ament_add_pytest_test(test_all test)
 endif()
 
 ament_package()

launch_py/__init__.py

@@ -12,13 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import importlib
-from typing import Any, List
+from typing import List
 
-from launch.frontend.expose import action_parse_methods
 from launch.frontend.parser import Parser
 from launch.launch_description import LaunchDescription
 
+from . import actions
 from .entity import Entity
 
 
@@ -28,25 +27,7 @@ def launch(actions: List[Entity]) -> LaunchDescription:
     return parser.parse_description(root_entity)
 
 
-def make_action(action_name):
-    def impl(**kwargs):
-        return Entity(action_name, kwargs)
-    globals()[action_name] = impl
-    return impl
-
-
-exposed_actions = [
-    make_action(key) for key in action_parse_methods.keys()
-]
-
 __all__ = [
     'launch',
-] + exposed_actions
-
-
-def __getattr__(name: str) -> Any:
-    # This is a workaround to silence mypy complaint about attributes that are created dynamically
-    try:
-        return importlib.import_module(f'.{name}', __name__)
-    except ModuleNotFoundError as e:
-        raise AttributeError(f'module {__name__} has no attribute {name}') from e
+    'actions',
+]

launch_py/actions.py

@@ -0,0 +1,50 @@
+# Copyright 2025 Polymath Robotics, Inc.
+#
+# 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.
+
+from typing import Any, Callable
+
+from launch.frontend.expose import action_parse_methods
+
+from .entity import Entity, is_reserved_identifier
+
+__all__ = []
+
+
+def make_action_factory(action_name: str, **kwargs) -> Callable[..., Entity]:
+    # Create a factory function for each action entity
+    def fn(**kwargs):
+        return Entity(action_name, kwargs)  # noqa: F821
+
+    # fn = FunctionType(impl_template.__code__, globals(), name=action_name)
+    fn.__doc__ = f'launch_py action: {action_name} (dynamically generated)'
+    fn.__name__ = action_name
+    fn.__qualname__ = action_name
+    fn.__module__ = __name__
+    return fn
+
+
+for action_name in action_parse_methods.keys():
+    if is_reserved_identifier(action_name):
+        action_name += '_'
+    fn = make_action_factory(action_name)
+    globals()[action_name] = fn
+    __all__.append(action_name)
+
+
+def __getattr__(name: str) -> Any:
+    # This is a workaround for mypy complaint about dynamically created attrs
+    import importlib
+    if name in __all__:
+        return importlib.import_module(f'.{name}', __name__)
+    raise AttributeError(f'module {__name__} has no attribute {name}')

launch_py/entity.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 
 """Module for launch_py Entity class."""
+import builtins
+import keyword
 from typing import (
     List,
     Optional,
@@ -30,6 +32,11 @@
 )
 
 
+def is_reserved_identifier(name: str) -> bool:
+    """Check if a name is a reserved identifier in Python."""
+    return keyword.iskeyword(name) or name in dir(builtins)
+
+
 class Entity(BaseEntity):
     """Single item in the intermediate front_end representation."""
 
@@ -44,7 +51,6 @@ def __init__(
         self.__type_name = type_name
         self.__kwargs = kwargs
         self.__parent = parent
-        self.__children_called = False
         self.__read_keys: Set[Text] = set()
 
     @property
@@ -60,7 +66,6 @@ def parent(self) -> Optional['Entity']:
     @property
     def children(self) -> List[BaseEntity]:
         """Get the Entity's children."""
-        self.__children_called = True
         if not isinstance(self.__kwargs, (dict)):
             raise TypeError(
                 f'Expected a dict, got {type(self.__kwargs)}:'
@@ -97,8 +102,7 @@ def get_attr(  # type: ignore[override]
         Access an attribute of the entity.
 
         See :py:meth:`launch.frontend.Entity.get_attr`.
-        `launch_yaml` does not apply type coercion,
-        it only checks if the read value is of the correct type.
+        Does not apply type coercion, only checks if the read value is of the correct type.
         """
         if name not in self.__kwargs:
             if not optional:
@@ -112,6 +116,8 @@ def get_attr(  # type: ignore[override]
         if check_is_list_entity(data_type):
             if isinstance(data, list) and isinstance(data[0], dict):
                 return [Entity(name, child) for child in data]
+            elif isinstance(data, list) and isinstance(data[0], Entity):
+                return data
             raise TypeError(
                 "Attribute '{}' of Entity '{}' expected to be a list of dictionaries.".format(
                     name, self.type_name

package.xml

@@ -17,7 +17,7 @@
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>
   <test_depend>ament_cmake_mypy</test_depend>
-  <test_depend>python3-pytest</test_depend>
+  <test_depend>ament_cmake_pytest</test_depend>
 
   <member_of_group>launch_frontend_packages</member_of_group>
 

test/basic_launch.py

@@ -11,10 +11,37 @@
 # 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.
-from launch_py import executable, launch
+from pathlib import Path
+
+from launch_py import launch
+from launch_py.actions import arg, executable, group, include, let, log, set_env
+
+THIS_DIR = Path(__file__).parent
 
 
 def generate_launch_description():
     return launch([
-        executable(cmd='echo hello launch_py world!', output='screen')
+        arg(name='arg1', default='arg1_value'),
+        let(name='arg2', value='let_$(var arg1)'),
+        executable(
+            cmd='echo hello launch_py executable',
+            output='screen',
+        ),
+        log(level='INFO', message='Log warning: arg1=$(var arg1), arg2=$(var arg2)'),
+        group(
+            children=[
+                set_env(
+                    name='MY_ENV_VAR',
+                    value='my_value',
+                ),
+                log(level='WARNING', message='In group env MY_ENV_VAR=$(env MY_ENV_VAR)'),
+            ]
+        ),
+        log(level='ERROR', message='Outside group: env MY_ENV_VAR=$(env MY_ENV_VAR "<unset>")'),
+        include(
+            file=f'{THIS_DIR}/include_launch.py',
+            arg=[
+                arg(name='foo', value='True'),
+            ],
+        ),
     ])

test/include_launch.py

@@ -0,0 +1,37 @@
+# Copyright 2025 Polymath Robotics, Inc.
+#
+# 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.
+
+from launch_py import launch
+from launch_py.actions import arg, log
+
+
+def generate_launch_description():
+    return launch([
+        arg(name='foo'),
+        log(
+            level='INFO',
+            message='I am an included launch file: foo=$(var foo)',
+        ),
+        # TODO(emerson) make if_ work
+        # log(
+        #     if_='$(var foo)',
+        #     level='INFO',
+        #     message='This conditional log only happened because foo is true',
+        # ),
+        # log(
+        #     if_='$(not $(var foo))',
+        #     level='INFO',
+        #     message='This conditional log only happened because foo is false',
+        # ),
+    ])

test/test_dynamic_attrs.py

@@ -0,0 +1,59 @@
+# Copyright 2025 Polymath Robotics, Inc.
+#
+# 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.
+
+from launch.action import Action
+from launch.frontend import expose_action
+import pytest
+
+
+@expose_action('while')
+class BuiltinNameTest(Action):
+    """Test action that exposes a Python builtin name."""
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+
+    @classmethod
+    def parse(cls, entity, parser):
+        _, kwargs = super().parse(entity, parser)
+        return cls, kwargs
+
+    def execute(self, context):
+        del context
+
+
+from launch_py import actions  # noqa: I100, E402
+
+
+def test_dynamic_attrs():
+    name = actions.let.__name__
+    assert name == 'let'
+    str_repr = str(actions.let)
+    assert str_repr.startswith('<function let')
+
+    assert actions.while_.__name__ == 'while_'
+
+    with pytest.raises(AttributeError):
+        getattr(actions, 'non_existent_action')
+
+    test_group = actions.group()
+    assert test_group.type_name == 'group'
+
+    test_arg = actions.arg(name='argname', default='argvalue')
+    assert test_arg.type_name == 'arg'
+    assert test_arg.get_attr('name') == 'argname'
+    assert test_arg.get_attr('default') == 'argvalue'
+
+    with pytest.raises(AttributeError):
+        test_arg.get_attr('non_existent_attr')