Make D-Bus element objects always have interface_name attribute

Use the common metaclass to set the value of `interface_name`.

If the D-Bus element is defined in the class without the interface
name passed raise a TypeError.

src/sdbus/dbus_common_elements.py

@@ -45,9 +45,8 @@
 
 
 class DbusSomethingCommon:
-    def __init__(self) -> None:
-        self.interface_name: Optional[str] = None
-        self.serving_enabled: bool = True
+    interface_name: str
+    serving_enabled: bool
 
 
 class DbusSomethingAsync(DbusSomethingCommon):
@@ -78,6 +77,23 @@ def __new__(cls, name: str,
             except NotImplementedError:
                 ...
 
+        for attr_name, attr in namespace.items():
+            if not isinstance(attr, DbusSomethingCommon):
+                continue
+
+            # TODO: Fix async metaclass copying all methods
+            if hasattr(attr, "interface_name"):
+                continue
+
+            if interface_name is None:
+                raise TypeError(
+                    f"Defined D-Bus element {attr_name!r} without "
+                    f"interface name in the class {name!r}."
+                )
+
+            attr.interface_name = interface_name
+            attr.serving_enabled = serving_enabled
+
         new_cls = super().__new__(cls, name, bases, namespace)
 
         return new_cls

src/sdbus/dbus_proxy_async_interface_base.py

@@ -87,8 +87,6 @@ def __new__(cls, name: str,
             )
 
             if isinstance(value, DbusSomethingAsync):
-                value.interface_name = interface_name
-                value.serving_enabled = serving_enabled
                 dbus_declared_members[key] = value
 
             if isinstance(value, DbusMethodAsync):

src/sdbus/dbus_proxy_async_method.py

@@ -80,7 +80,6 @@ async def _call_dbus_async(self, *args: Any) -> Any:
         assert interface._attached_bus is not None
         assert interface._remote_service_name is not None
         assert interface._remote_object_path is not None
-        assert self.dbus_method.interface_name is not None
         new_call_message = interface._attached_bus. \
             new_method_call_message(
                 interface._remote_service_name,

src/sdbus/dbus_proxy_async_property.py

@@ -130,7 +130,6 @@ async def get_async(self) -> T:
         assert interface._remote_service_name is not None
         assert interface._remote_object_path is not None
         assert self.dbus_property.property_name is not None
-        assert self.dbus_property.interface_name is not None
         new_call_message = interface._attached_bus. \
             new_property_get_message(
                 interface._remote_service_name,
@@ -162,7 +161,6 @@ def _reply_set_sync(self, message: SdBusMessage) -> None:
 
         self.dbus_property.property_setter(interface, data_to_set_to)
 
-        assert self.dbus_property.interface_name is not None
         try:
             properties_changed = getattr(interface, 'properties_changed')
         except AttributeError:
@@ -217,7 +215,6 @@ async def set_async(self, complete_object: T) -> None:
         assert interface._remote_service_name is not None
         assert interface._remote_object_path is not None
         assert self.dbus_property.property_name is not None
-        assert self.dbus_property.interface_name is not None
         new_call_message = interface._attached_bus. \
             new_property_set_message(
                 interface._remote_service_name,

src/sdbus/dbus_proxy_async_signal.py

@@ -81,7 +81,6 @@ async def _get_dbus_queue(self) -> Queue[SdBusMessage]:
         assert interface._attached_bus is not None
         assert interface._remote_service_name is not None
         assert interface._remote_object_path is not None
-        assert self.dbus_signal.interface_name is not None
         assert self.dbus_signal.signal_name is not None
 
         return await interface._attached_bus.get_signal_queue_async(
@@ -201,7 +200,6 @@ def _emit_message(self, args: T) -> None:
 
         assert interface._attached_bus is not None
         assert interface._serving_object_path is not None
-        assert self.dbus_signal.interface_name is not None
         assert self.dbus_signal.signal_name is not None
 
         signal_message = interface._attached_bus.new_signal_message(

src/sdbus/dbus_proxy_sync_interface_base.py

@@ -58,8 +58,6 @@ def __new__(cls, name: str,
             )
 
             if isinstance(value, DbusSomethingSync):
-                value.interface_name = interface_name
-                value.serving_enabled = serving_enabled
                 declared_interfaces.add(key)
 
             if isinstance(value, DbusMethodSync):

src/sdbus/dbus_proxy_sync_method.py

@@ -55,7 +55,6 @@ def __init__(self,
         self.__doc__ = dbus_method.__doc__
 
     def _call_dbus_sync(self, *args: Any) -> Any:
-        assert self.dbus_method.interface_name is not None
         new_call_message = self.interface._attached_bus. \
             new_method_call_message(
                 self.interface._remote_service_name,

src/sdbus/dbus_proxy_sync_property.py

@@ -69,7 +69,6 @@ def __get__(self,
             "This is probably an error as it will block "
             "other asyncio methods for considerable time."
         )
-        assert self.interface_name is not None
 
         new_call_message = obj._attached_bus. \
             new_property_get_message(
@@ -97,7 +96,6 @@ def __set__(self, obj: DbusInterfaceBase, value: T) -> None:
         assert obj._remote_service_name is not None
         assert obj._remote_object_path is not None
         assert self.property_name is not None
-        assert self.interface_name is not None
         new_call_message = obj._attached_bus. \
             new_property_set_message(
                 obj._remote_service_name,

test/test_sdbus_async_bad_class.py

@@ -22,8 +22,6 @@
 from unittest import TestCase
 from unittest import main as unittest_main
 
-from sdbus.dbus_common_funcs import PROPERTY_FLAGS_MASK, count_bits
-
 from sdbus import (
     DbusDeprecatedFlag,
     DbusInterfaceCommonAsync,
@@ -34,11 +32,15 @@
     dbus_property_async,
     dbus_signal_async,
 )
+from sdbus.dbus_common_funcs import PROPERTY_FLAGS_MASK, count_bits
 
 from .common_test_util import skip_if_no_asserts, skip_if_no_name_validations
 
 
-class TestInterface(DbusInterfaceCommonAsync):
+class TestInterface(
+    DbusInterfaceCommonAsync,
+    interface_name="org.example.test",
+):
     @dbus_method_async(result_signature="i")
     async def test_int(self) -> int:
         return 1
@@ -170,6 +172,22 @@ class TestInheritence2(TestInterface):
                 async def test_unrelated(self) -> int:
                     return 2
 
+    def test_dbus_elements_without_interface_name(self) -> None:
+        with self.assertRaisesRegex(TypeError, "without interface name"):
+
+            class NoInterfaceName(DbusInterfaceCommonAsync):
+                @dbus_method_async()
+                async def example(self) -> None:
+                    ...
+
+    def test_dbus_elements_without_interface_name_subclass(self) -> None:
+        with self.assertRaisesRegex(TypeError, "without interface name"):
+
+            class NoInterfaceName(TestInterface):
+                @dbus_method_async()
+                async def example(self) -> None:
+                    ...
+
 
 if __name__ == "__main__":
     unittest_main()

test/test_sdbus_block_bad_class.py

@@ -27,7 +27,10 @@
 from .common_test_util import skip_if_no_name_validations
 
 
-class GoodDbusInterface(DbusInterfaceCommon):
+class GoodDbusInterface(
+    DbusInterfaceCommon,
+    interface_name="org.example.test",
+):
     @dbus_method()
     def test_method(self) -> None:
         raise NotImplementedError
@@ -118,6 +121,14 @@ class BadPropertyName(
                 def test(self) -> str:
                     return "test"
 
+    def test_dbus_elements_without_interface_name(self) -> None:
+        with self.assertRaisesRegex(TypeError, "without interface name"):
+
+            class NoInterfaceName(DbusInterfaceCommon):
+                @dbus_method()
+                def example(self) -> None:
+                    ...
+
 
 if __name__ == "__main__":
     unittest_main()