Expose Python code generation via rosidl generate CLI

Signed-off-by: Michel Hidalgo <[email protected]>

rosidl_generator_py/package.xml

@@ -26,6 +26,7 @@
   <buildtool_export_depend>rosidl_typesupport_interface</buildtool_export_depend>
 
   <exec_depend>python3-numpy</exec_depend>
+  <exec_depend>rosidl_cli</exec_depend>
   <exec_depend>rosidl_generator_c</exec_depend>
   <exec_depend>rosidl_parser</exec_depend>
   <exec_depend>rosidl_runtime_c</exec_depend>

rosidl_generator_py/rosidl_generator_py/cli.py

@@ -0,0 +1,49 @@
+# Copyright 2021 Open Source Robotics Foundation, 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.
+
+import os
+
+from ament_index_python import get_package_share_directory
+from ament_index_python import get_resources
+
+from rosidl_cli.command.generate.extensions import GenerateCommandExtension
+from rosidl_cli.command.generate.helpers import legacy_generator_arguments_file
+
+from rosidl_generator_py import generate_py
+
+
+class GeneratePython(GenerateCommandExtension):
+
+    def generate(
+        self,
+        package_name,
+        interface_files,
+        include_paths,
+        output_path
+    ):
+        package_share_path = \
+            get_package_share_directory(
+                'rosidl_generator_py'
+            )
+        templates_path = os.path.join(
+            package_share_path, 'resource'
+        )
+        typesupport_implementations = ['rosidl_typesupport_c']
+        typesupport_implementations.extend(get_resources('rosidl_typesupport_c'))
+        with legacy_generator_arguments_file(
+            package_name, interface_files,
+            include_paths, templates_path,
+            output_path
+        ) as path_to_arguments_file:
+            generate_py(path_to_arguments_file, typesupport_implementations)

rosidl_generator_py/setup.cfg

@@ -0,0 +1,3 @@
+[options.entry_points]
+rosidl_cli.command.generate.type_extensions =
+  py = rosidl_generator_py.cli:GeneratePython