NumPy "base" feature: integrated feedback by @aldanor

include/pybind11/numpy.h

@@ -157,7 +157,7 @@ NAMESPACE_END(detail)
 #define PyArrayDescr_GET_(ptr, attr) \
     (reinterpret_cast<::pybind11::detail::PyArrayDescr_Proxy*>(ptr)->attr)
 #define PyArray_FLAGS_(ptr) \
-    (reinterpret_cast<::pybind11::detail::PyArray_Proxy*>(ptr)->flags)
+    PyArray_GET_(ptr, flags)
 #define PyArray_CHKFLAGS_(ptr, flag) \
     (flag == (PyArray_FLAGS_(ptr) & flag))
 

tests/test_numpy_array.cpp

@@ -109,4 +109,19 @@ test_initializer numpy_array([](py::module &m) {
             a
         );
     });
+
+    struct ArrayClass {
+        int data[2] = { 1, 2 };
+        ArrayClass() { py::print("ArrayClass()"); }
+        ~ArrayClass() { py::print("~ArrayClass()"); }
+    };
+
+    py::class_<ArrayClass>(sm, "ArrayClass")
+        .def(py::init<>())
+        .def("numpy_view", [](py::object &obj) {
+            py::print("ArrayClass::numpy_view()");
+            ArrayClass &a = obj.cast<ArrayClass&>();
+            return py::array_t<int>({2}, {4}, a.data, obj);
+        }
+    );
 });

tests/test_numpy_array.py

 import pytest
+import gc
 
 with pytest.suppress(ImportError):
     import numpy as np
@@ -209,3 +210,31 @@ def test_wrap():
     A1 = A1.diagonal()
     A2 = wrap(A1)
     assert_references(A1, A2)
+
+
+@pytest.requires_numpy
+def test_numpy_view(capture):
+    from pybind11_tests.array import ArrayClass
+    with capture:
+        ac = ArrayClass()
+        ac_view_1 = ac.numpy_view()
+        ac_view_2 = ac.numpy_view()
+        assert np.all(ac_view_1 == np.array([1, 2], dtype=np.int32))
+        del ac
+        gc.collect()
+    assert capture == """
+        ArrayClass()
+        ArrayClass::numpy_view()
+        ArrayClass::numpy_view()
+    """
+    ac_view_1[0] = 4
+    ac_view_1[1] = 3
+    assert ac_view_2[0] == 4
+    assert ac_view_2[1] == 3
+    with capture:
+        del ac_view_1
+        del ac_view_2
+        gc.collect()
+    assert capture == """
+        ~ArrayClass()
+    """