feat: Treat ListObject as a Python collections.abc.Sequence, which is generic over the SettingsBase objects it stores and enabling slice support.

doc/changelog.d/5117.added.md

@@ -0,0 +1 @@
+Make ListObject a Sequence

doc/source/user_guide/solver_settings/solver_settings_contents.rst

@@ -82,13 +82,13 @@ of container objects: :obj:`~ansys.fluent.core.solver.flobject.Group`,
   children can be accessed via ``<NamedObject>.get_object_names()``.
 
 - The :obj:`~ansys.fluent.core.solver.flobject.ListObject` type is a container holding dynamically
-  created unnamed objects of
+  created, unnamed objects of
   its specified child type (accessible via a ``child_object_type`` attribute) in a
-  list. Children of a ``ListObject`` object can be accessed using the index operator.
+  :term:`sequence`\. ``ListObject`` behaves much like a tuple though it supports :meth:`object.__setitem__`. 
+  Children of a ``ListObject`` object can be accessed using the index operator.
   For example, ``solver_session.settings.setup.cell_zone_conditions.fluid['fluid-1'].sources.terms['mass'][2]``
   refers to the third (starting from index 0) mass source entry for the fluid zone
-  named ``fluid-1``. The current number of child objects can be accessed with the
-  ``get_size()`` method.
+  named ``fluid-1``.
 
 .. vale Google.Spacing = YES
 

src/ansys/fluent/core/solver/flobject.py

@@ -41,6 +41,7 @@
 from __future__ import annotations
 
 import collections
+from collections.abc import Sequence
 from contextlib import contextmanager, nullcontext, suppress
 from enum import Enum
 import fnmatch
@@ -69,6 +70,7 @@
     _eval_type,
     get_args,
     get_origin,
+    overload,
 )
 import warnings
 import weakref
@@ -1352,7 +1354,7 @@ def __setitem__(self, name, value):
         self[name].set_state(value)
 
 
-ChildTypeT = TypeVar("ChildTypeT")
+ChildTypeT = TypeVar("ChildTypeT", bound="SettingsBase")
 
 
 class NamedObject(SettingsBase[DictStateType], Generic[ChildTypeT]):
@@ -1618,7 +1620,7 @@ def _rename(obj: NamedObject | _Alias, new: str, old: str):
     obj._create_child_object(new)
 
 
-class ListObject(SettingsBase[ListStateType], Generic[ChildTypeT]):
+class ListObject(SettingsBase[ListStateType], Sequence[ChildTypeT]):
     """A ``ListObject`` container is a container object, similar to a Python list
     object. Generally, many such objects can be created.
 
@@ -1692,10 +1694,18 @@ def get_size(self) -> int:
         """
         return self.flproxy.get_list_size(self.path)
 
-    def __getitem__(self, index: int) -> ChildTypeT:
+    @overload
+    def __getitem__(self, index: int) -> ChildTypeT: ...
+
+    @overload
+    def __getitem__(self, index: slice) -> list[ChildTypeT]: ...
+
+    def __getitem__(self, index: int | slice) -> ChildTypeT | list[ChildTypeT]:
         size = self.get_size()
-        if index >= size:
-            raise IndexError(index)
+        if isinstance(index, int):
+            if index >= size:
+                raise IndexError(index)
+
         if len(self._objects) != size:
             self._update_objects()
         return self._objects[index]

tests/test_flobject.py

@@ -537,9 +537,22 @@ def test_list_object():
         {"il_1": None, "bl_1": None},
         {"il_1": [1, 2], "bl_1": None},
     ]
+
+    assert r.l_1[0:1][0].il_1() is None
+    assert r.l_1[1:2][0].il_1() == [1, 2]
+
     r.l_1 = [{"il_1": [3], "bl_1": [True, False]}]
     assert r.l_1() == [{"il_1": [3], "bl_1": [True, False]}]
 
+    r.l_1 = [
+        {"il_1": [1], "bl_1": None},
+        {"il_1": None, "bl_1": None},
+        {"il_1": [2], "bl_1": None},
+        {"il_1": None, "bl_1": None},
+        {"il_1": [3], "bl_1": None},
+    ]
+    assert [inner.il_1() for inner in r.l_1[::2]] == [[1], [2], [3]]
+
 
 def test_list_object_set_state_with_quantity_values():
     class RealWithUnits(Real):