Iterate interfaces in the MRO reversed order

arkq · arkq · commit b853432e57af · 2025-06-16T10:05:45.000+02:00
Iterating the MRO in the reversed order will allow to add interfaces to
the given object in a well-defined way - always starting from the base
class. Such ordering will be compatible with adding interfaces manually
one by one.
diff --git a/src/sdbus/dbus_proxy_async_interface_base.py b/src/sdbus/dbus_proxy_async_interface_base.py
@@ -295,7 +295,7 @@ def _dbus_iter_interfaces_meta(
         cls,
     ) -> Iterator[tuple[str, DbusClassMeta]]:
 
-        for base in cls.__mro__:
+        for base in reversed(cls.__mro__):
             meta = DBUS_CLASS_TO_META.get(base)
             if meta is None:
                 continue
diff --git a/src/sdbus/dbus_proxy_async_interfaces.py b/src/sdbus/dbus_proxy_async_interfaces.py
@@ -105,6 +105,7 @@ async def properties_get_all_dict(
 
 
 class DbusInterfaceCommonAsync(
-        DbusPeerInterfaceAsync, DbusPropertiesInterfaceAsync,
-        DbusIntrospectableAsync):
+        DbusPropertiesInterfaceAsync,
+        DbusIntrospectableAsync,
+        DbusPeerInterfaceAsync):
     ...
diff --git a/src/sdbus/dbus_proxy_sync_interface_base.py b/src/sdbus/dbus_proxy_sync_interface_base.py
@@ -171,7 +171,7 @@ def _dbus_iter_interfaces_meta(
         cls,
     ) -> Iterator[tuple[str, DbusClassMeta]]:
 
-        for base in cls.__mro__:
+        for base in reversed(cls.__mro__):
             meta = DBUS_CLASS_TO_META.get(base)
             if meta is None:
                 continue
diff --git a/src/sdbus/dbus_proxy_sync_interfaces.py b/src/sdbus/dbus_proxy_sync_interfaces.py
@@ -94,9 +94,9 @@ def properties_get_all_dict(
 
 
 class DbusInterfaceCommon(
-        DbusPeerInterface,
+        DbusPropertiesInterface,
         DbusIntrospectable,
-        DbusPropertiesInterface):
+        DbusPeerInterface):
     ...
 
 
diff --git a/test/test_sdbus_async.py b/test/test_sdbus_async.py
@@ -948,9 +948,23 @@ class TwoInterface(
             async def two(self) -> int:
                 return 2
 
-        class CombinedInterface(OneInterface, TwoInterface):
+        class CombinedInterface(TwoInterface, OneInterface):
             ...
 
+        test_combined = CombinedInterface()
+        test_combined_interfaces = [
+            iface for iface, _ in test_combined._dbus_iter_interfaces_meta()
+        ]
+
+        # Verify the order of reported interfaces on the combined class.
+        self.assertEqual(test_combined_interfaces, [
+            "org.freedesktop.DBus.Peer",
+            "org.freedesktop.DBus.Introspectable",
+            "org.freedesktop.DBus.Properties",
+            "org.example.one",
+            "org.example.two",
+        ])
+
     async def test_extremely_large_string(self) -> None:
         test_object, test_object_connection = initialize_object()
 
diff --git a/test/test_sdbus_block.py b/test/test_sdbus_block.py
@@ -92,9 +92,23 @@ class TwoInterface(
             def two(self) -> int:
                 raise NotImplementedError
 
-        class CombinedInterface(OneInterface, TwoInterface):
+        class CombinedInterface(TwoInterface, OneInterface):
             ...
 
+        test_combined = CombinedInterface("org.test", "/")
+        test_combined_interfaces = [
+            iface for iface, _ in test_combined._dbus_iter_interfaces_meta()
+        ]
+
+        # Verify the order of reported interfaces on the combined class.
+        self.assertEqual(test_combined_interfaces, [
+            "org.freedesktop.DBus.Peer",
+            "org.freedesktop.DBus.Introspectable",
+            "org.freedesktop.DBus.Properties",
+            "org.example.one",
+            "org.example.two",
+        ])
+
 
 if __name__ == '__main__':
     main()
