Mailman 3 subclassing array in c - NumPy-Discussion

March 8, 2012

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Hi, 

I have been struggeling for quite some time now. Desperate as I am, now I need help. 

I was trying to subclass ndarrays in a c extension (see code below) and do constantly get segfaults. I have been checking my INCREF and DECREF stuff up and down but can't find the error. Probably I got something completely wrong... anybody able to help?

Thanks,
Christoph
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#include <Python.h>
#include <structmember.h>

#include <numpy/arrayobject.h>

static PyObject *SpamError;

typedef struct {
  PyArrayObject base;
  PyDictObject* unit;
} UnitArrayObject;

PyTypeObject unitArrayObjectType;

static int
checkunit(PyObject *unit1, PyObject *unit2) {
  return PyObject_Compare(unit1, unit2);
}

static PyObject *
unitArray_new(PyTypeObject *cls, PyObject *args, PyObject *kwargs) {
	PyObject *data = NULL,
			 *unit = NULL;
  PyArray_Descr* dtype = NULL;
  PyObject *res = NULL, *tmp = NULL;

	if (!PyArg_ParseTuple(args, "OO|O&", &data, &unit, PyArray_DescrConverter, &dtype)) {
		Py_XDECREF(dtype);
		return NULL;
	}

  res = PyArray_FromAny(data, dtype, 0, 0, NPY_ENSURECOPY, NULL);
	if (res == NULL) {
		Py_XDECREF(dtype);
    //TODO: raise exception?
		return NULL;
	}

	if (PyObject_IsInstance(data, (PyObject*)cls)) {
		if (unit!=NULL && !checkunit((PyObject*)((UnitArrayObject*)data)->unit,unit)) {
			Py_XDECREF(res);
 			//TODO: raise exception
			return NULL;
		}
	} else {
		if (PyObject_IsTrue(unit)) {
      tmp = res;
			res = PyArray_View((PyArrayObject*)res, NULL, &unitArrayObjectType);
      if (tmp!=res) {
        Py_XDECREF(tmp);
      }
      ((UnitArrayObject*)res)->unit = (PyDictObject*)unit;
      Py_INCREF(unit);
      if (unit!=NULL) {
      }
		}
	}
	return res;
}

static PyObject*
unitArray__array_finalize__(PyObject* new, PyObject* args) {
	PyObject *attr = NULL, *tmp = NULL;
  PyObject *parent = NULL;

  if (!PyArg_ParseTuple(args, "O", &parent)) {
    return NULL;
  }
   if (parent!=NULL) {
     attr = PyObject_GetAttrString(parent, "unit");
     if (attr == NULL) {
        //parent has no 'unit' so we make a new empty one
       attr = PyDict_New();
       PyErr_Clear();
     }
   } 
  tmp = (PyObject*)((UnitArrayObject*)new)->unit;
    ((UnitArrayObject*)new)->unit = (PyDictObject*)attr;

  Py_INCREF(Py_None);
  return Py_None;
}

static PyObject* 
unitArray__array_wrap__(PyObject *self, PyObject *args) {
	PyObject *array = NULL, *context = NULL;

	if (!PyArg_ParseTuple(args, "OO", array, context)) {
		//TODO: raise exception
		return NULL;
	}

	printf("%s",PyString_AsString(PyObject_Str(context)));

  Py_INCREF(array);
  return array;
}

static PyMethodDef unitArrayMethods[] = {
  {"__array_finalize__", unitArray__array_finalize__, METH_VARARGS, "array finalize method"},
  {"__array_wrap__", unitArray__array_wrap__, METH_VARARGS, "array wrap method"},
  {NULL, NULL, 0, NULL}
};

static PyMemberDef unitArrayMembers[] = {
  {"unit", T_OBJECT, offsetof(UnitArrayObject, unit),  0, "dictionary containing unit info."},
  {NULL, 0, 0, 0, NULL}
};

PyTypeObject unitArrayObjectType = {
	PyObject_HEAD_INIT(NULL)
	0,				/* ob_size        */
	"spam.UnitArray",		/* tp_name        */
	sizeof(UnitArrayObject),		/* tp_basicsize   */
	0,				/* tp_itemsize    */
	0,				/* tp_dealloc     */
	0,				/* tp_print       */
	0,				/* tp_getattr     */
	0,				/* tp_setattr     */
	0,				/* tp_compare     */
	0,				/* tp_repr        */
	0,				/* tp_as_number   */
	0,				/* tp_as_sequence */
	0,				/* tp_as_mapping  */
	0,				/* tp_hash        */
	0,				/* tp_call        */
	0,				/* tp_str         */
	0,				/* tp_getattro    */
	0,				/* tp_setattro    */
	0,				/* tp_as_buffer   */
	Py_TPFLAGS_DEFAULT,		/* tp_flags       */
	"A numpy array with units",	/* tp_doc         */
  0,        /* traverseproc */
  0,        /* tp_clear*/
  0,        /* tp_richcompare */
  0,        /* tp_weaklistoffset */
  0,        /* tp_iter */
  0,        /* tp_iternext */
  unitArrayMethods,        /* tp_methods */
  unitArrayMembers,        /* tp_members */
  0,        /* tp_getset */
  0,        /* tp_base*/
  0,        /* tp_dict */
  0,        /* tp_descr_get*/
  0,        /* tp_descr_set */
  0,        /* tp_dictoffset */
  0,        /* tp_init */
  0,        /* tp_alloc */
  unitArray_new /* tp_new */
};

static PyMethodDef SpamMethods[] = {
    {NULL, NULL, 0, NULL}        /* Sentinel */
};

PyObject *unitArray = NULL;
PyMODINIT_FUNC
initspampub(void)
{
  import_array();

  PyObject *m;

  Py_INCREF(&PyArray_Type);
  unitArrayObjectType.tp_base = &PyArray_Type;

  if (PyType_Ready(&unitArrayObjectType) < 0)
    return;

  m = Py_InitModule3("spampub", SpamMethods, "some tests and a array type with units.");
  if (m == NULL)
    return;

  SpamError = PyErr_NewException("spampub.error", NULL, NULL);
  Py_INCREF(SpamError);
  PyModule_AddObject(m, "error", SpamError);
  Py_INCREF(&unitArrayObjectType);
  PyModule_AddObject(m, "UnitArray", (PyObject *)&unitArrayObjectType);
  (void) Py_InitModule("spampub", SpamMethods);

}

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subclassing array in c

Christoph Gohle

Val Kalatsky

Val Kalatsky

Christoph Gohlke

Christoph Gohle

Val Kalatsky

Christoph Gohle

Pauli Virtanen

Christoph Gohle

Christoph Gohle

Francesc Alted

Pauli Virtanen

Christoph Gohle

Christoph Gohle

mark florisson

Chris Barker

mark florisson

mark florisson

mark florisson

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