Initialize allocated cython.array buffer with object dtype to None

Cython/Compiler/MemoryView.py

@@ -476,7 +476,7 @@ def assign_scalar(dst, scalar, code):
     p = slice_iter_obj.start_loops()
 
     if dtype.is_pyobject:
-        code.putln("Py_DECREF((PyObject *) %s);" % p)
+        code.putln("Py_DECREF(*(PyObject **) %s);" % p)
 
     code.putln("*((%s *) %s) = __pyx_temp_scalar;" % (type_decl, p))
 

Cython/Utility/MemoryView.pyx

@@ -13,6 +13,10 @@ cdef extern from "Python.h":
         PyBUF_FORMAT
         PyBUF_WRITABLE
 
+    ctypedef struct PyObject
+    PyObject *Py_None
+    void Py_INCREF(PyObject *)
+
 
 cdef extern from *:
     object __pyx_memoryview_new(object obj, int flags, bint dtype_is_object)
@@ -45,6 +49,10 @@ cdef class array:
     def __cinit__(array self, tuple shape, Py_ssize_t itemsize, format not None,
                   mode=u"c", bint allocate_buffer=True):
 
+        cdef int idx
+        cdef Py_ssize_t i
+        cdef PyObject **p
+
         self.ndim = len(shape)
         self.itemsize = itemsize
 
@@ -68,7 +76,6 @@ cdef class array:
             free(self._strides)
             raise MemoryError("unable to allocate shape or strides.")
 
-        cdef int idx
         # cdef Py_ssize_t dim, stride
         idx = 0
         for idx, dim in enumerate(shape):
@@ -96,12 +103,17 @@ cdef class array:
         self.mode = mode
 
         self.free_data = allocate_buffer
+        self.dtype_is_object = format == b'O'
         if allocate_buffer:
             self.data = <char *>malloc(self.len)
             if not self.data:
                 raise MemoryError("unable to allocate array data.")
 
-        self.dtype_is_object = format == b'O'
+            if self.dtype_is_object:
+                p = <PyObject **> self.data
+                for i in range(self.len / itemsize):
+                    p[i] = Py_None
+                    Py_INCREF(Py_None)
 
     def __getbuffer__(self, Py_buffer *info, int flags):
         cdef int bufmode = -1

tests/run/memslice.pyx

@@ -1888,13 +1888,11 @@ class SingleObject(object):
     def __str__(self):
         return str(self.value)
 
+    def __eq__(self, other):
+        return self.value == getattr(other, 'value', None) or self.value == other
+
 cdef _get_empty_object_slice(fill=None):
     cdef cython.array a = cython.array((10,), sizeof(PyObject *), 'O')
-    cdef int i
-    for i in range(10):
-        (<PyObject **> a.data)[i] = <PyObject *> fill
-        Py_INCREF(fill)
-
     assert a.dtype_is_object
     return a
 
@@ -1976,7 +1974,6 @@ def test_scalar_slice_assignment():
     print
     _test_scalar_slice_assignment(<object> m, <object> m2)
 
-
 cdef _test_scalar_slice_assignment(slice_1d m, slice_2d m2):
     cdef int i, j
     for i in range(10):
@@ -2034,3 +2031,15 @@ def test_contig_scalar_to_slice_assignment():
 
     m[:, :] = 20
     print m[0, 0], m[-1, -1], m[3, 2], m[4, 9]
+
+@testcase
+def test_dtype_object_scalar_assignment():
+    """
+    >>> test_dtype_object_scalar_assignment()
+    """
+    cdef object[:] m = cython.array((10,), sizeof(PyObject *), 'O')
+    m[:] = SingleObject(2)
+    assert m[0] == m[4] == m[-1] == 2
+
+    (<object> m)[:] = SingleObject(3)
+    assert m[0] == m[4] == m[-1] == 3