> Okay, is my understanding here correct? I am defining two type
> descriptors:
> PyArray_Descr mxNumpyType - describes the Numpy array type.
> PyTypeObject mxNumpyDataType - describes the data type of the contents
> of the array (i.e. mxNumpyType->typeobj points to this), inherits from
> PyDoubleArrType_Type and overrides some fields as mentioned above.
>
The nomenclature is that mxNumPyType is the data-type of the array and
your PyTypeObject is the "type" of the elements of the array. So, you
have the names a bit backward.
So, to correspond with the way I use the words "type" and "data-type", I
would name them:
PyArray_Descr mxNumpyDataType
PyTypeObject mxNumpyType
Okay, I will use this convention going forwards.
> And the getitem and setitem functions are designed to only give/take
> PyObject* of type mxDateTime.
>
These are in the 'f' member of the PyArray_Descr structure, so
presumably you have also filled in your PyArray_Descr structure with
items from PyArray_DOUBLE?
That's correct. I have all members of the 'f' member identical to that from PyArray_DOUBLE, except:
mxNumpyType->f->dotfunc = NULL;
mxNumpyType->f->getitem = date_getitem;
mxNumpyType->f->setitem = date_setitem;
mxNumpyType->f->cast[PyArray_DOUBLE] = (PyArray_VectorUnaryFunc*) dateToDouble;
mxNumpyType->f->cast[PyArray_OBJECT] = (PyArray_VectorUnaryFunc*) dateToObject;
All other cast functions are NULL.
If I redefine the string function, I encounter another, perhaps more serious problem leading to a segfault. I've defined my string function to be extremely simple:
>>> def printer(arr):
... return str(arr[0])
Now, if I try to print an element of the array:
>>> mxArr[0]
I get to this stack trace:
#0 scalar_value (scalar=0x814be10, descr=0x5079e0) at scalartypes.inc.src:68
#1 0x0079936a in PyArray_Scalar (data="" descr=0x5079e0, base=0x814e7a8) at arrayobject.c:1419
#2 0x007d259f in array_subscript_nice (self=0x814e7a8, op=0x804eb8c) at arrayobject.c:1985
#3 0x00d17dde in PyObject_GetItem (o=0x814e7a8, key=0x804eb8c) at Objects/abstract.c:94
(Note: for some reason gdb claims that arrayobject.c:1985 is array_subscript_nice, but looking at my source this line is actually in array_item_nice. *boggle*)
Perhaps scalar_value should be checking the scalarkind field of PyArray_Descr, or using the elsize and alignment fields to figure out the pointer to return if scalarkind isn't set?
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