python: add a dedicated test for StridedArrayView of a dynamic type.

Yup, this could work very well for MeshData / SceneData generic
attribute and field access with what's already there, no changes needed.

src/python/corrade/test/test_containers.py

@@ -902,6 +902,35 @@ class StridedArrayViewCustomType(unittest.TestCase):
     # mutable_vector3d and mutable_long_float tested in test_containers_numpy
     # as memoryview can't handle their types
 
+class StridedArrayViewCustomDynamicType(unittest.TestCase):
+    def test_float(self):
+        a = test_stridedarrayview.MutableContainerDynamicType('f')
+        self.assertEqual(a.view.size, (2, 3))
+        self.assertEqual(a.view.stride, (12, 4))
+        self.assertEqual(a.view.format, 'f')
+        a.view[0][1] = 15.0
+        a.view[1][0] = -22.0
+        self.assertEqual(a.view[0][0], 0.0)
+        self.assertEqual(a.view[0][1], 15.0)
+        self.assertEqual(a.view[0][2], 0.0)
+        self.assertEqual(a.view[1][0], -22.0)
+        self.assertEqual(a.view[1][1], 0.0)
+        self.assertEqual(a.view[1][2], 0.0)
+
+    def test_int(self):
+        a = test_stridedarrayview.MutableContainerDynamicType('i')
+        self.assertEqual(a.view.size, (2, 3))
+        self.assertEqual(a.view.stride, (12, 4))
+        self.assertEqual(a.view.format, 'i')
+        a.view[0][2] = 15
+        a.view[1][1] = -773
+        self.assertEqual(a.view[0][0], 0)
+        self.assertEqual(a.view[0][1], 0)
+        self.assertEqual(a.view[0][2], 15)
+        self.assertEqual(a.view[1][0], 0)
+        self.assertEqual(a.view[1][1], -773)
+        self.assertEqual(a.view[1][2], 0)
+
 class TestOptional(unittest.TestCase):
     def test_simple(self):
         self.assertIsNone(test_optional.simple_type(False))

src/python/corrade/test/test_containers_numpy.py

@@ -130,3 +130,28 @@ class StridedArrayViewCustomType(unittest.TestCase):
             (1001, 1.125),
             (4666025, -7.5)
         ])
+
+class StridedArrayViewCustomDynamicType(unittest.TestCase):
+    def test_short_short(self):
+        a = test_stridedarrayview.MutableContainerDynamicType('hh')
+        self.assertEqual(a.view.size, (2, 3))
+        self.assertEqual(a.view.stride, (12, 4))
+        self.assertEqual(a.view.format, 'hh')
+
+        # Test that numpy understands the type and has changes reflected
+        av = np.array(a.view, copy=False)
+        av[1][0] = (22563, -17665)
+        a.view[0][1] = (15, 34)
+        a.view[1][1] = (-22, 18)
+        # Converting to a tuple, otherwise numpy always compares to False
+        self.assertEqual(tuple(av[0][1]), (15, 34))
+        self.assertEqual(tuple(av[1][0]), (22563, -17665))
+        self.assertEqual(tuple(av[1][1]), (-22, 18))
+
+        # And the other way around as well
+        self.assertEqual(a.view[0][0], (0, 0))
+        self.assertEqual(a.view[0][1], (15, 34))
+        self.assertEqual(a.view[0][2], (0, 0))
+        self.assertEqual(a.view[1][0], (22563, -17665))
+        self.assertEqual(a.view[1][1], (-22, 18))
+        self.assertEqual(a.view[1][2], (0, 0))

src/python/corrade/test/test_stridedarrayview.cpp

@@ -57,6 +57,17 @@ template<class T> struct Container {
     T data[3*2]{};
 };
 
+struct MutableContainerDynamicType {
+    explicit MutableContainerDynamicType(const std::string& format): format{format} {}
+
+    Containers::StridedArrayView2D<void> view() {
+        return {Containers::arrayView(data), {2, 3}, {12, 4}};
+    }
+
+    std::string format;
+    char data[3*2*4]{};
+};
+
 template<class T> void container(py::class_<Container<T>>& c) {
     c
         .def(py::init())
@@ -81,6 +92,41 @@ PYBIND11_MODULE(test_stridedarrayview, m) {
     container(mutableContainer3d);
     container(mutableContainerlf);
 
+    py::class_<MutableContainerDynamicType>{m, "MutableContainerDynamicType"}
+        .def(py::init<const std::string&>())
+        .def_property_readonly("view", [](MutableContainerDynamicType & self) {
+            std::size_t itemsize;
+            py::object(*getitem)(const char*);
+            void(*setitem)(char*, py::handle);
+            if(self.format == "f") {
+                itemsize = 4;
+                getitem = [](const char* item) {
+                    return py::cast(*reinterpret_cast<const float*>(item));
+                };
+                setitem = [](char* item, py::handle object) {
+                    *reinterpret_cast<float*>(item) = py::cast<float>(object);
+                };
+            } else if(self.format == "i") {
+                itemsize = 4;
+                getitem = [](const char* item) {
+                    return py::cast(*reinterpret_cast<const int*>(item));
+                };
+                setitem = [](char* item, py::handle object) {
+                    *reinterpret_cast<int*>(item) = py::cast<int>(object);
+                };
+            } else if(self.format == "hh") {
+                itemsize = 4;
+                getitem = [](const char* item) {
+                    return py::cast(*reinterpret_cast<const std::pair<short, short>*>(item));
+                };
+                setitem = [](char* item, py::handle object) {
+                    *reinterpret_cast<std::pair<short, short>*>(item) = py::cast<std::pair<short, short>>(object);
+                };
+            } else throw py::attribute_error{};
+
+            return Containers::pyArrayViewHolder(Containers::PyStridedArrayView<2, char>{Containers::arrayCast<char>(self.view()), self.format.data(), itemsize, getitem, setitem}, py::cast(self));
+        });
+
     m.def("get_containers", []() {
         return Container<const std::int16_t>{3, -17565, 5};
     });