Use cpp_function for defining properties

Author: franzpoeschel

src/binding/python/Iteration.cpp

@@ -94,18 +94,22 @@ void init_Iteration(py::module &m)
         .def("set_dt", &Iteration::setDt<double>)
         .def("set_time_unit_SI", &Iteration::setTimeUnitSI)
 
-        .def_readwrite(
+        .def_property_readonly(
             "meshes",
-            &Iteration::meshes,
-            py::return_value_policy::copy,
-            // garbage collection: return value must be freed before Iteration
-            py::keep_alive<1, 0>())
-        .def_readwrite(
+            py::cpp_function(
+                [](Iteration &i) { return i.meshes; },
+                py::return_value_policy::copy,
+                // garbage collection: return value must be freed before
+                // Iteration
+                py::keep_alive<1, 0>()))
+        .def_property_readonly(
             "particles",
-            &Iteration::particles,
-            py::return_value_policy::copy,
-            // garbage collection: return value must be freed before Iteration
-            py::keep_alive<1, 0>());
+            py::cpp_function(
+                [](Iteration &i) { return i.particles; },
+                py::return_value_policy::copy,
+                // garbage collection: return value must be freed before
+                // Iteration
+                py::keep_alive<1, 0>()));
 
     add_pickle(
         cl, [](openPMD::Series series, std::vector<std::string> const &group) {

src/binding/python/ParticleSpecies.cpp

@@ -48,12 +48,13 @@ void init_ParticleSpecies(py::module &m)
               return stream.str();
           })
 
-        .def_readwrite(
+        .def_property_readonly(
             "particle_patches",
-            &ParticleSpecies::particlePatches,
-            py::return_value_policy::copy,
-            // garbage collection: return value must be freed before Series
-            py::keep_alive<1, 0>());
+            py::cpp_function(
+                [](ParticleSpecies &ps) { return ps.particlePatches; },
+                py::return_value_policy::copy,
+                // garbage collection: return value must be freed before Series
+                py::keep_alive<1, 0>()));
     add_pickle(
         cl, [](openPMD::Series series, std::vector<std::string> const &group) {
             uint64_t const n_it = std::stoull(group.at(1));

src/binding/python/Series.cpp

@@ -497,12 +497,13 @@ this method.
         .def("set_iteration_format", &Series::setIterationFormat)
         .def("set_name", &Series::setName)
 
-        .def_readwrite(
+        .def_property_readonly(
             "iterations",
-            &Series::iterations,
-            py::return_value_policy::copy,
-            // garbage collection: return value must be freed before Series
-            py::keep_alive<1, 0>())
+            py::cpp_function(
+                [](Series &s) { return s.iterations; },
+                py::return_value_policy::copy,
+                // garbage collection: return value must be freed before Series
+                py::keep_alive<1, 0>()))
         .def(
             "read_iterations",
             [](Series &s) {