Fix iterator return value policies

Author: HaarigerHarald

source/analysis/accumulables/pyG4AccumulableManager.cc

@@ -37,5 +37,5 @@ void export_G4AccumulableManager(py::module &m)
       .def("Reset", &G4AccumulableManager::Reset, py::call_guard<py::gil_scoped_release>())
       .def(
          "__iter__", [](G4AccumulableManager &self) { return py::make_iterator(self.Begin(), self.End()); },
-         py::is_operator());
+         py::is_operator(), py::return_value_policy::reference_internal);
 }

source/geometry/management/pyG4Region.cc

@@ -57,7 +57,7 @@ void export_G4Region(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def(
          "GetMaterialIterator",
@@ -67,7 +67,7 @@ void export_G4Region(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def("GetNumberOfMaterials", &G4Region::GetNumberOfMaterials)
       .def("GetNumberOfRootVolumes", &G4Region::GetNumberOfRootVolumes)

source/geometry/navigation/pyG4TransportationManager.cc

@@ -72,7 +72,7 @@ void export_G4TransportationManager(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def("GetNoWorlds", &G4TransportationManager::GetNoWorlds)
       .def(
@@ -83,7 +83,7 @@ void export_G4TransportationManager(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def("GetSafetyHelper", &G4TransportationManager::GetSafetyHelper, py::return_value_policy::reference)
       .def("GetParallelWorld", &G4TransportationManager::GetParallelWorld, py::arg("worldName"),

source/geometry/volumes/pyG4AssemblyVolume.cc

@@ -55,7 +55,7 @@ void export_G4AssemblyVolume(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def("TotalImprintedVolumes", &G4AssemblyVolume::TotalImprintedVolumes)
       .def("GetImprintTransformation", &G4AssemblyVolume::GetImprintTransformation, py::arg("imprintID"))
@@ -67,7 +67,7 @@ void export_G4AssemblyVolume(py::module &m)
 
             return py::make_iterator(begin, end);
          },
-         py::keep_alive<0, 1>())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
       .def("TotalTriplets", &G4AssemblyVolume::TotalTriplets)
       .def("GetImprintsCount", &G4AssemblyVolume::GetImprintsCount)

source/materials/pyG4ExtendedMaterial.cc

@@ -43,5 +43,5 @@ void export_G4ExtendedMaterial(py::module &m)
 
       .def(
          "__iter__", [](G4ExtendedMaterial &self) { return py::make_iterator(self.begin(), self.end()); },
-         py::keep_alive<0, 1>(), py::is_operator());
+         py::is_operator(), py::return_value_policy::reference_internal);
 }

source/particles/pyG4ParticleList.cc

@@ -53,24 +53,28 @@ PyG4ParticleList::ParticleList PyG4ParticleList::particleTableCache;
 
 void export_PyG4ParticleList(py::module &m)
 {
-   py::class_<PyG4ParticleList>(m, "PyG4ParticleList", "particle list")
+   py::class_<PyG4ParticleList, py::nodelete>(m, "PyG4ParticleList", "particle list")
       .def(py::init<>())
       .def(
-         "__iter__", [](PyG4ParticleList &self) { py::make_iterator(self.p_begin(), self.p_end()); }, py::is_operator())
+         "__iter__", [](PyG4ParticleList &self) { py::make_iterator(self.p_begin(), self.p_end()); }, py::is_operator(),
+         py::return_value_policy::reference_internal)
 
       .def(
          "__getitem__",
          [](PyG4ParticleList &self, size_t i) {
             self.p_begin();
             return self.particleTableCache[i];
          },
-         py::is_operator())
+         py::is_operator(), py::return_value_policy::reference_internal)
 
-      .def_property_readonly("particles", [](PyG4ParticleList &self) {
-         py::list list;
-         for (auto it = self.p_begin(); it < self.p_end(); it++) {
-            list.append(it);
-         }
-         return list;
-      });
+      .def_property_readonly(
+         "particles",
+         [](PyG4ParticleList &self) {
+            py::list list;
+            for (auto it = self.p_begin(); it < self.p_end(); it++) {
+               list.append(it);
+            }
+            return list;
+         },
+         py::return_value_policy::reference_internal);
 }