Provide base classes in rosidl_pycommon (#887)

Signed-off-by: Michael Carlstrom <[email protected]>

Author: InvincibleRMC

rosidl_pycommon/rosidl_pycommon/interface_base_classes.py

@@ -0,0 +1,90 @@
+# Copyright 2025 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.
+
+# Base Classes
+from abc import ABC
+from abc import ABCMeta
+from abc import abstractmethod
+from typing import Any
+from typing import ClassVar
+from typing import Generic
+from typing import TypeVar
+
+
+class MessageTypeSupportMeta(ABCMeta):
+
+    _CREATE_ROS_MESSAGE: ClassVar[Any]
+    _CONVERT_FROM_PY: ClassVar[Any]
+    _CONVERT_TO_PY: ClassVar[Any]
+    _DESTROY_ROS_MESSAGE: ClassVar[Any]
+    _TYPE_SUPPORT: ClassVar[Any]
+
+    @classmethod
+    @abstractmethod
+    def __import_type_support__(cls) -> None: ...
+
+
+class BaseMessage(ABC, metaclass=MessageTypeSupportMeta):
+
+    __slots__ = ()
+
+    @abstractmethod
+    def __repr__(self) -> str: ...
+
+    @abstractmethod
+    def __eq__(self, other: object) -> bool: ...
+
+    @classmethod
+    @abstractmethod
+    def get_fields_and_field_types(cls) -> dict[str, str]: ...
+
+
+RequestT = TypeVar('RequestT')
+ResponseT = TypeVar('ResponseT')
+
+
+class ServiceTypeSupportMeta(ABCMeta):
+
+    _TYPE_SUPPORT: ClassVar[Any]
+
+    @classmethod
+    @abstractmethod
+    def __import_type_support__(cls) -> None: ...
+
+
+class BaseService(ABC, Generic[RequestT, ResponseT], metaclass=ServiceTypeSupportMeta):
+
+    Request: type[RequestT]
+    Response: type[ResponseT]
+
+
+GoalT = TypeVar('GoalT')
+ResultT = TypeVar('ResultT')
+FeedbackT = TypeVar('FeedbackT')
+
+
+class ActionTypeSupportMeta(ABCMeta):
+
+    _TYPE_SUPPORT: ClassVar[Any]
+
+    @classmethod
+    @abstractmethod
+    def __import_type_support__(cls) -> None: ...
+
+
+class BaseAction(ABC, Generic[GoalT, ResultT, FeedbackT], metaclass=ActionTypeSupportMeta):
+
+    Goal: type[GoalT]
+    Result: type[ResultT]
+    Feedback: type[FeedbackT]