split py->slot & slot->py into their own functions & fixed some mistakes with conversion.

1 files changed, 556 insertions, 525 deletions

diff --git a/source/blender/python/bmesh/bmesh_py_ops_call.c b/source/blender/python/bmesh/bmesh_py_ops_call.c
index 9dadf6c2bac..222ceadbc3d 100644
--- a/source/blender/python/bmesh/bmesh_py_ops_call.c
+++ b/source/blender/python/bmesh/bmesh_py_ops_call.c
@@ -60,443 +60,617 @@ static int bpy_bm_op_as_py_error(BMesh *bm)
 }
 
 /**
- * This is the __call__ for bmesh.ops.xxx()
+ * Use for giving py args to an operator.
  */
-PyObject *BPy_BMO_call(BPy_BMeshOpFunc *self, PyObject *args, PyObject *kw)
+static int bpy_slot_from_py(BMesh *bm, BMOperator *bmop, BMOpSlot *slot, PyObject *value,
+                            /* the are just for exception messages */
+                            const char *opname, const char *slot_name)
 {
-	PyObject *ret;
-	BPy_BMesh *py_bm;
-	BMesh *bm;
-
-	BMOperator bmop;
-
-	if ((PyTuple_GET_SIZE(args) == 1) &&
-	    (py_bm = (BPy_BMesh *)PyTuple_GET_ITEM(args, 0)) &&
-	    (BPy_BMesh_Check(py_bm))
-		)
-	{
-		BPY_BM_CHECK_OBJ(py_bm);
-		bm = py_bm->bm;
-	}
-	else {
-		PyErr_SetString(PyExc_TypeError,
-		                "calling a bmesh operator expects a single BMesh (non keyword) "
-		                "as the first argument");
-		return NULL;
-	}
+	switch (slot->slot_type) {
+		case BMO_OP_SLOT_BOOL:
+		{
+			int param;
 
-	/* TODO - error check this!, though we do the error check on attribute access */
-	/* TODO - make flags optional */
-	BMO_op_init(bm, &bmop, BMO_FLAG_DEFAULTS, self->opname);
+			param = PyLong_AsLong(value);
 
-	if (kw && PyDict_Size(kw) > 0) {
-		/* setup properties, see bpy_rna.c: pyrna_py_to_prop()
-		 * which shares this logic for parsing properties */
-
-		PyObject *key, *value;
-		Py_ssize_t pos = 0;
-		while (PyDict_Next(kw, &pos, &key, &value)) {
-			const char *slot_name = _PyUnicode_AsString(key);
-			BMOpSlot *slot = BMO_slot_get(bmop.slots_in, slot_name);
+			if (param < 0) {
+				PyErr_Format(PyExc_TypeError,
+				             "%.200s: keyword \"%.200s\" expected True/False or 0/1, not %.200s",
+				             opname, slot_name, Py_TYPE(value)->tp_name);
+				return -1;
+			}
+			else {
+				BMO_SLOT_AS_BOOL(slot) = param;
+			}
 
-			if (slot == NULL) {
+			break;
+		}
+		case BMO_OP_SLOT_INT:
+		{
+			int overflow;
+			long param = PyLong_AsLongAndOverflow(value, &overflow);
+			if (overflow || (param > INT_MAX) || (param < INT_MIN)) {
+				PyErr_Format(PyExc_ValueError,
+				             "%.200s: keyword \"%.200s\" value not in 'int' range "
+				             "(" STRINGIFY(INT_MIN) ", " STRINGIFY(INT_MAX) ")",
+				             opname, slot_name, Py_TYPE(value)->tp_name);
+				return -1;
+			}
+			else if (param == -1 && PyErr_Occurred()) {
 				PyErr_Format(PyExc_TypeError,
-				             "%.200s: keyword \"%.200s\" is invalid for this operator",
-				             self->opname, slot_name);
-				return NULL;
+				             "%.200s: keyword \"%.200s\" expected an int, not %.200s",
+				             opname, slot_name, Py_TYPE(value)->tp_name);
+				return -1;
+			}
+			else {
+				BMO_SLOT_AS_INT(slot) = (int)param;
+			}
+			break;
+		}
+		case BMO_OP_SLOT_FLT:
+		{
+			float param = PyFloat_AsDouble(value);
+			if (param == -1 && PyErr_Occurred()) {
+				PyErr_Format(PyExc_TypeError,
+				             "%.200s: keyword \"%.200s\" expected a float, not %.200s",
+				             opname, slot_name, Py_TYPE(value)->tp_name);
+				return -1;
+			}
+			else {
+				BMO_SLOT_AS_FLOAT(slot) = param;
+			}
+			break;
+		}
+		case BMO_OP_SLOT_MAT:
+		{
+			/* XXX - BMesh operator design is crappy here, operator slot should define matrix size,
+			 * not the caller! */
+			unsigned short size;
+			if (!MatrixObject_Check(value)) {
+				PyErr_Format(PyExc_TypeError,
+				             "%.200s: keyword \"%.200s\" expected a Matrix, not %.200s",
+				             opname, slot_name, Py_TYPE(value)->tp_name);
+				return -1;
+			}
+			else if (BaseMath_ReadCallback((MatrixObject *)value) == -1) {
+				return -1;
+			}
+			else if (((size = ((MatrixObject *)value)->num_col) != ((MatrixObject *)value)->num_row) ||
+			         (ELEM(size, 3, 4) == FALSE))
+			{
+				PyErr_Format(PyExc_TypeError,
+				             "%.200s: keyword \"%.200s\" expected a 3x3 or 4x4 matrix Matrix",
+				             opname, slot_name);
+				return -1;
 			}
 
-			/* now assign the value */
-			switch (slot->slot_type) {
-				case BMO_OP_SLOT_BOOL:
+			BMO_slot_mat_set(bmop, bmop->slots_in, slot_name, ((MatrixObject *)value)->matrix, size);
+			break;
+		}
+		case BMO_OP_SLOT_VEC:
+		{
+			/* passing slot name here is a bit non-descriptive */
+			if (mathutils_array_parse(BMO_SLOT_AS_VECTOR(slot), 3, 3, value, slot_name) == -1) {
+				return -1;
+			}
+			break;
+		}
+		case BMO_OP_SLOT_ELEMENT_BUF:
+		{
+			if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
+				if (!BPy_BMElem_Check(value) ||
+				    !(((BPy_BMElem *)value)->ele->head.htype & slot->slot_subtype.elem))
 				{
-					int param;
+					PyErr_Format(PyExc_TypeError,
+					             "%.200s: keyword \"%.200s\" expected a %.200s not *.200s",
+					             opname, slot_name,
+					             BPy_BMElem_StringFromHType(slot->slot_subtype.elem & BM_ALL_NOLOOP),
+					             Py_TYPE(value)->tp_name);
+					return -1;
+				}
+				else if (((BPy_BMElem *)value)->bm == NULL) {
+					PyErr_Format(PyExc_TypeError,
+					             "%.200s: keyword \"%.200s\" invalidated element",
+					             opname, slot_name);
+					return -1;
+				}
+
+				BMO_slot_buffer_from_single(bmop, slot, &((BPy_BMElem *)value)->ele->head);
+			}
+			else {
+				/* there are many ways we could interpret arguments, for now...
+				 * - verts/edges/faces from the mesh direct,
+				 *   this way the operator takes every item.
+				 * - `TODO` a plain python sequence (list) of elements.
+				 * - `TODO`  an iterator. eg.
+				 *   face.verts
+				 * - `TODO`  (type, flag) pair, eg.
+				 *   ('VERT', {'TAG'})
+				 */
+
+#define BPY_BM_GENERIC_MESH_TEST(type_string)  \
+if (((BPy_BMGeneric *)value)->bm != bm) {                                             \
+	PyErr_Format(PyExc_NotImplementedError,                                           \
+	             "%.200s: keyword \"%.200s\" " type_string " are from another bmesh", \
+	             opname, slot_name, slot->slot_type);                           \
+	return -1;                                                                        \
+	} (void)0
+
+#define BPY_BM_ELEM_TYPE_TEST(type_string)  \
+	if ((slot->slot_subtype.elem & BM_VERT) == 0) { \
+	PyErr_Format(PyExc_TypeError, \
+	             "%.200s: keyword \"%.200s\" expected " \
+	             "a list of %.200s not " type_string, \
+	             opname, slot_name, \
+	             BPy_BMElem_StringFromHType(slot->slot_subtype.elem & BM_ALL_NOLOOP)); \
+	return -1; \
+	} (void)0
 
-					param = PyLong_AsLong(value);
+				if (BPy_BMVertSeq_Check(value)) {
+					BPY_BM_GENERIC_MESH_TEST("verts");
+					BPY_BM_ELEM_TYPE_TEST("verts");
+
+					BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_VERT);
+				}
+				else if (BPy_BMEdgeSeq_Check(value)) {
+					BPY_BM_GENERIC_MESH_TEST("edges");
+					BPY_BM_ELEM_TYPE_TEST("edges");
+					BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_EDGE);
+				}
+				else if (BPy_BMFaceSeq_Check(value)) {
+					BPY_BM_GENERIC_MESH_TEST("faces");
+					BPY_BM_ELEM_TYPE_TEST("faces");
+					BMO_slot_buffer_from_all(bm, bmop, bmop->slots_in, slot_name, BM_FACE);
+				}
+
+#undef BPY_BM_ELEM_TYPE_TEST
 
-					if (param < 0) {
-						PyErr_Format(PyExc_TypeError,
-						             "%.200s: keyword \"%.200s\" expected True/False or 0/1, not %.200s",
-						             self->opname, slot_name, Py_TYPE(value)->tp_name);
-						return NULL;
+				else if (BPy_BMElemSeq_Check(value)) {
+					BMIter iter;
+					BMHeader *ele;
+					int tot;
+					unsigned int i;
+
+					BPY_BM_GENERIC_MESH_TEST("elements");
+
+					/* this will loop over all elements which is a shame but
+					 * we need to know this before alloc */
+					/* calls bpy_bmelemseq_length() */
+					tot = Py_TYPE(value)->tp_as_sequence->sq_length((PyObject *)value);
+
+					BMO_slot_buffer_alloc(bmop, bmop->slots_in, slot_name, tot);
+
+					i = 0;
+					BM_ITER_BPY_BM_SEQ (ele, &iter, ((BPy_BMElemSeq *)value)) {
+						slot->data.buf[i] = ele;
+						i++;
 					}
-					else {
-						BMO_SLOT_AS_BOOL(slot) = param;
+				}
+				/* keep this last */
+				else if (PySequence_Check(value)) {
+					BMElem **elem_array = NULL;
+					Py_ssize_t elem_array_len;
+
+					elem_array = BPy_BMElem_PySeq_As_Array(&bm, value, 0, PY_SSIZE_T_MAX,
+					                                       &elem_array_len, (slot->slot_subtype.elem & BM_ALL_NOLOOP),
+					                                       TRUE, TRUE, slot_name);
+
+					/* error is set above */
+					if (elem_array == NULL) {
+						return -1;
 					}
 
-					break;
+					BMO_slot_buffer_alloc(bmop, bmop->slots_in, slot_name, elem_array_len);
+					memcpy(slot->data.buf, elem_array, sizeof(void *) * elem_array_len);
+					PyMem_FREE(elem_array);
+				}
+				else {
+					PyErr_Format(PyExc_TypeError,
+					             "%.200s: keyword \"%.200s\" expected "
+					             "a bmesh sequence, list, (htype, flag) pair, not %.200s",
+					             opname, slot_name, Py_TYPE(value)->tp_name);
+					return -1;
+				}
+			}
+#undef BPY_BM_GENERIC_MESH_TEST
+
+			break;
+		}
+		case BMO_OP_SLOT_MAPPING:
+		{
+			/* first check types */
+			if (slot->slot_subtype.map != BMO_OP_SLOT_SUBTYPE_MAP_EMPTY) {
+				if (!PyDict_Check(value)) {
+					PyErr_Format(PyExc_TypeError,
+					             "%.200s: keyword \"%.200s\" expected "
+					             "a dict, not %.200s",
+					             opname, slot_name, Py_TYPE(value)->tp_name);
+					return -1;
 				}
-				case BMO_OP_SLOT_INT:
+			}
+			else {
+				if (!PySet_Check(value)) {
+					PyErr_Format(PyExc_TypeError,
+					             "%.200s: keyword \"%.200s\" expected "
+					             "a set, not %.200s",
+					             opname, slot_name, Py_TYPE(value)->tp_name);
+					return -1;
+				}
+			}
+
+			switch (slot->slot_subtype.map) {
+
+				/* this could be a static function */
+#define BPY_BM_MAPPING_KEY_CHECK(arg_key)  \
+				if (!BPy_BMElem_Check(arg_key)) { \
+					PyErr_Format(PyExc_TypeError, \
+					             "%.200s: keyword \"%.200s\" expected " \
+					             "a dict with bmesh element keys, not %.200s", \
+					             opname, slot_name, Py_TYPE(arg_key)->tp_name); \
+					return -1; \
+				} \
+				else if (((BPy_BMGeneric *)arg_key)->bm == NULL) { \
+					PyErr_Format(PyExc_TypeError, \
+					             "%.200s: keyword \"%.200s\" invalidated element key in dict", \
+					             opname, slot_name); \
+					return -1; \
+				} (void)0
+
+
+				case BMO_OP_SLOT_SUBTYPE_MAP_ELEM:
 				{
-					int overflow;
-					long param = PyLong_AsLongAndOverflow(value, &overflow);
-					if (overflow || (param > INT_MAX) || (param < INT_MIN)) {
-						PyErr_Format(PyExc_ValueError,
-						             "%.200s: keyword \"%.200s\" value not in 'int' range "
-						             "(" STRINGIFY(INT_MIN) ", " STRINGIFY(INT_MAX) ")",
-						             self->opname, slot_name, Py_TYPE(value)->tp_name);
-						return NULL;
-					}
-					else if (param == -1 && PyErr_Occurred()) {
-						PyErr_Format(PyExc_TypeError,
-						             "%.200s: keyword \"%.200s\" expected an int, not %.200s",
-						             self->opname, slot_name, Py_TYPE(value)->tp_name);
-						return NULL;
-					}
-					else {
-						BMO_SLOT_AS_INT(slot) = (int)param;
+					if (PyDict_Size(value) > 0) {
+						PyObject *arg_key, *arg_value;
+						Py_ssize_t arg_pos = 0;
+						while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
+							/* TODO, check the elements come from the right mesh? */
+							BPY_BM_MAPPING_KEY_CHECK(arg_key);
+
+							if (!BPy_BMElem_Check(arg_value)) {
+								PyErr_Format(PyExc_TypeError,
+								             "%.200s: keyword \"%.200s\" expected "
+								             "a dict with bmesh element values, not %.200s",
+								             opname, slot_name, Py_TYPE(arg_value)->tp_name);
+								return -1;
+							}
+							else if (((BPy_BMGeneric *)arg_value)->bm == NULL) {
+								PyErr_Format(PyExc_TypeError,
+								             "%.200s: keyword \"%.200s\" invalidated element value in dict",
+								             opname, slot_name);
+								return -1;
+							}
+
+							BMO_slot_map_elem_insert(bmop, slot,
+							                         ((BPy_BMElem *)arg_key)->ele, ((BPy_BMElem *)arg_value)->ele);
+						}
 					}
 					break;
 				}
-				case BMO_OP_SLOT_FLT:
+				case BMO_OP_SLOT_SUBTYPE_MAP_FLOAT:
 				{
-					float param = PyFloat_AsDouble(value);
-					if (param == -1 && PyErr_Occurred()) {
-						PyErr_Format(PyExc_TypeError,
-						             "%.200s: keyword \"%.200s\" expected a float, not %.200s",
-						             self->opname, slot_name, Py_TYPE(value)->tp_name);
-						return NULL;
-					}
-					else {
-						BMO_SLOT_AS_FLOAT(slot) = param;
+					if (PyDict_Size(value) > 0) {
+						PyObject *arg_key, *arg_value;
+						Py_ssize_t arg_pos = 0;
+						while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
+							float value_f;
+							/* TODO, check the elements come from the right mesh? */
+							BPY_BM_MAPPING_KEY_CHECK(arg_key);
+							value_f = PyFloat_AsDouble(arg_value);
+
+							if (value_f == -1.0f && PyErr_Occurred()) {
+								PyErr_Format(PyExc_TypeError,
+								             "%.200s: keyword \"%.200s\" expected "
+								             "a dict with float values, not %.200s",
+								             opname, slot_name, Py_TYPE(arg_value)->tp_name);
+								return -1;
+							}
+
+							BMO_slot_map_float_insert(bmop, slot,
+							                          ((BPy_BMElem *)arg_key)->ele, value_f);
+						}
 					}
 					break;
 				}
-				case BMO_OP_SLOT_MAT:
+				case BMO_OP_SLOT_SUBTYPE_MAP_INT:
 				{
-					/* XXX - BMesh operator design is crappy here, operator slot should define matrix size,
-					 * not the caller! */
-					unsigned short size;
-					if (!MatrixObject_Check(value)) {
-						PyErr_Format(PyExc_TypeError,
-						             "%.200s: keyword \"%.200s\" expected a Matrix, not %.200s",
-						             self->opname, slot_name, Py_TYPE(value)->tp_name);
-						return NULL;
-					}
-					else if (BaseMath_ReadCallback((MatrixObject *)value) == -1) {
-						return NULL;
-					}
-					else if (((size = ((MatrixObject *)value)->num_col) != ((MatrixObject *)value)->num_row) ||
-					         (ELEM(size, 3, 4) == FALSE))
-					{
-						PyErr_Format(PyExc_TypeError,
-						             "%.200s: keyword \"%.200s\" expected a 3x3 or 4x4 matrix Matrix",
-						             self->opname, slot_name);
-						return NULL;
-					}
+					if (PyDict_Size(value) > 0) {
+						PyObject *arg_key, *arg_value;
+						Py_ssize_t arg_pos = 0;
+						while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
+							int value_i;
+							/* TODO, check the elements come from the right mesh? */
+							BPY_BM_MAPPING_KEY_CHECK(arg_key);
+							value_i = PyLong_AsLong(arg_value);
+
+							if (value_i == -1 && PyErr_Occurred()) {
+								PyErr_Format(PyExc_TypeError,
+								             "%.200s: keyword \"%.200s\" expected "
+								             "a dict with int values, not %.200s",
+								             opname, slot_name, Py_TYPE(arg_value)->tp_name);
+								return -1;
+							}
 
-					BMO_slot_mat_set(&bmop, bmop.slots_in, slot_name, ((MatrixObject *)value)->matrix, size);
+							BMO_slot_map_int_insert(bmop, slot,
+							                        ((BPy_BMElem *)arg_key)->ele, value_i);
+						}
+					}
 					break;
 				}
-				case BMO_OP_SLOT_VEC:
+				case BMO_OP_SLOT_SUBTYPE_MAP_BOOL:
 				{
-					/* passing slot name here is a bit non-descriptive */
-					if (mathutils_array_parse(BMO_SLOT_AS_VECTOR(slot), 3, 3, value, slot_name) == -1) {
-						return NULL;
+					if (PyDict_Size(value) > 0) {
+						PyObject *arg_key, *arg_value;
+						Py_ssize_t arg_pos = 0;
+						while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
+							int value_i;
+							/* TODO, check the elements come from the right mesh? */
+							BPY_BM_MAPPING_KEY_CHECK(arg_key);
+							value_i = PyLong_AsLong(arg_value);
+
+							if (value_i == -1 && PyErr_Occurred()) {
+								PyErr_Format(PyExc_TypeError,
+								             "%.200s: keyword \"%.200s\" expected "
+								             "a dict with bool values, not %.200s",
+								             opname, slot_name, Py_TYPE(arg_value)->tp_name);
+								return -1;
+							}
+
+							BMO_slot_map_bool_insert(bmop, slot,
+							                         ((BPy_BMElem *)arg_key)->ele, value_i != 0);
+						}
 					}
 					break;
 				}
-				case BMO_OP_SLOT_ELEMENT_BUF:
+				case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY:
 				{
-					if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
-						if (!BPy_BMElem_Check(value) ||
-						    !(((BPy_BMElem *)value)->ele->head.htype & slot->slot_subtype.elem))
-						{
-							PyErr_Format(PyExc_TypeError,
-							             "%.200s: keyword \"%.200s\" expected a %.200s not *.200s",
-							             self->opname, slot_name,
-							             BPy_BMElem_StringFromHType(slot->slot_subtype.elem & BM_ALL_NOLOOP),
-							             Py_TYPE(value)->tp_name);
-							return NULL;
-						}
-						else if (((BPy_BMElem *)value)->bm == NULL) {
-							PyErr_Format(PyExc_TypeError,
-							             "%.200s: keyword \"%.200s\" invalidated element",
-							             self->opname, slot_name);
-							return NULL;
+					if (PySet_Size(value) > 0) {
+						PyObject *arg_key;
+						Py_ssize_t arg_pos = 0;
+						Py_ssize_t arg_hash = 0;
+						while (_PySet_NextEntry(value, &arg_pos, &arg_key, &arg_hash)) {
+							/* TODO, check the elements come from the right mesh? */
+							BPY_BM_MAPPING_KEY_CHECK(arg_key);
+
+							BMO_slot_map_empty_insert(bmop, slot,
+							                         ((BPy_BMElem *)arg_key)->ele);
 						}
-
-						BMO_slot_buffer_from_single(&bmop, slot, &((BPy_BMElem *)value)->ele->head);
 					}
-					else {
-						/* there are many ways we could interpret arguments, for now...
-						 * - verts/edges/faces from the mesh direct,
-						 *   this way the operator takes every item.
-						 * - `TODO` a plain python sequence (list) of elements.
-						 * - `TODO`  an iterator. eg.
-						 *   face.verts
-						 * - `TODO`  (type, flag) pair, eg.
-						 *   ('VERT', {'TAG'})
-						 */
-
-#define BPY_BM_GENERIC_MESH_TEST(type_string)  \
-	if (((BPy_BMGeneric *)value)->bm != bm) {                                             \
-	    PyErr_Format(PyExc_NotImplementedError,                                           \
-	                 "%.200s: keyword \"%.200s\" " type_string " are from another bmesh", \
-	                 self->opname, slot_name, slot->slot_type);                           \
-	    return NULL;                                                                      \
-	} (void)0
-
-#define BPY_BM_ELEM_TYPE_TEST(type_string)  \
-	if ((slot->slot_subtype.elem & BM_VERT) == 0) { \
-	    PyErr_Format(PyExc_TypeError, \
-	                 "%.200s: keyword \"%.200s\" expected " \
-	                 "a list of %.200s not " type_string, \
-	                 self->opname, slot_name, \
-	                 BPy_BMElem_StringFromHType(slot->slot_subtype.elem & BM_ALL_NOLOOP)); \
-	    return NULL; \
-	} (void)0
-
-						if (BPy_BMVertSeq_Check(value)) {
-							BPY_BM_GENERIC_MESH_TEST("verts");
-							BPY_BM_ELEM_TYPE_TEST("verts");
-
-							BMO_slot_buffer_from_all(bm, &bmop, bmop.slots_in, slot_name, BM_VERT);
-						}
-						else if (BPy_BMEdgeSeq_Check(value)) {
-							BPY_BM_GENERIC_MESH_TEST("edges");
-							BPY_BM_ELEM_TYPE_TEST("edges");
-							BMO_slot_buffer_from_all(bm, &bmop, bmop.slots_in, slot_name, BM_EDGE);
-						}
-						else if (BPy_BMFaceSeq_Check(value)) {
-							BPY_BM_GENERIC_MESH_TEST("faces");
-							BPY_BM_ELEM_TYPE_TEST("faces");
-							BMO_slot_buffer_from_all(bm, &bmop, bmop.slots_in, slot_name, BM_FACE);
-						}
+					break;
+				}
+				case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL:
+				{
+					/* can't convert from these */
+					PyErr_Format(PyExc_NotImplementedError,
+					             "This arguments mapping subtype %d is not supported", slot->slot_subtype);
+					return -1;
+				}
+#undef BPY_BM_MAPPING_KEY_CHECK
 
-#undef BPY_BM_ELEM_TYPE_TEST
+			}
+		}
+		default:
+			/* TODO --- many others */
+			PyErr_Format(PyExc_NotImplementedError,
+			             "%.200s: keyword \"%.200s\" type %d not working yet!",
+			             opname, slot_name, slot->slot_type);
+			return -1;
+	}
 
-						else if (BPy_BMElemSeq_Check(value)) {
-							BMIter iter;
-							BMHeader *ele;
-							int tot;
-							unsigned int i;
+	/* all is well */
+	return 0;
+}
 
-							BPY_BM_GENERIC_MESH_TEST("elements");
+/**
+ * Use for getting return values from an operator thats already executed.
+ *
+ * \note Don't throw any exceptions and should always return a valid (PyObject *).
+ */
+static PyObject* bpy_slot_to_py(BMesh *bm, BMOpSlot *slot)
+{
+	PyObject *item = NULL;
+
+	/* keep switch in same order as above */
+	switch (slot->slot_type) {
+		case BMO_OP_SLOT_BOOL:
+			item = PyBool_FromLong((BMO_SLOT_AS_BOOL(slot)));
+			break;
+		case BMO_OP_SLOT_INT:
+			item = PyLong_FromLong(BMO_SLOT_AS_INT(slot));
+			break;
+		case BMO_OP_SLOT_FLT:
+			item = PyFloat_FromDouble((double)BMO_SLOT_AS_FLOAT(slot));
+			break;
+		case BMO_OP_SLOT_MAT:
+			item = Matrix_CreatePyObject((float *)BMO_SLOT_AS_MATRIX(slot), 4, 4, Py_NEW, NULL);
+			break;
+		case BMO_OP_SLOT_VEC:
+			item = Vector_CreatePyObject(BMO_SLOT_AS_VECTOR(slot), slot->len, Py_NEW, NULL);
+			break;
+		case BMO_OP_SLOT_PTR:
+			BLI_assert(0);  /* currently we don't have any pointer return values in use */
+			item = (Py_INCREF(Py_None), Py_None);
+			break;
+		case BMO_OP_SLOT_ELEMENT_BUF:
+		{
+			if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
+				BMHeader *ele = BMO_slot_buffer_get_single(slot);
+				item = ele ? BPy_BMElem_CreatePyObject(bm, ele) : (Py_INCREF(Py_None), Py_None);
+			}
+			else {
+				const int size = slot->len;
+				void **buffer = BMO_SLOT_AS_BUFFER(slot);
+				int j;
+
+				item = PyList_New(size);
+				for (j = 0; j < size; j++) {
+					BMHeader *ele = buffer[j];
+					PyList_SET_ITEM(item, j, BPy_BMElem_CreatePyObject(bm, ele));
+				}
+			}
+			break;
+		}
+		case BMO_OP_SLOT_MAPPING:
+		{
+			GHash *slot_hash = BMO_SLOT_AS_GHASH(slot);
+			GHashIterator hash_iter;
 
-							/* this will loop over all elements which is a shame but
-							 * we need to know this before alloc */
-							/* calls bpy_bmelemseq_length() */
-							tot = Py_TYPE(value)->tp_as_sequence->sq_length((PyObject *)self);
+			switch (slot->slot_subtype.map) {
+				case BMO_OP_SLOT_SUBTYPE_MAP_ELEM:
+				{
+					item = PyDict_New();
+					if (slot_hash) {
+						GHASH_ITER (hash_iter, slot_hash) {
+							BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
+							BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
 
-							BMO_slot_buffer_alloc(&bmop, bmop.slots_in, slot_name, tot);
+							PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
+							PyObject *py_val =  BPy_BMElem_CreatePyObject(bm, *(void **)BMO_OP_SLOT_MAPPING_DATA(ele_val));
 
-							i = 0;
-							BM_ITER_BPY_BM_SEQ (ele, &iter, ((BPy_BMElemSeq *)value)) {
-								slot->data.buf[i] = ele;
-								i++;
-							}
-						}
-						/* keep this last */
-						else if (PySequence_Check(value)) {
-							BMElem **elem_array = NULL;
-							Py_ssize_t elem_array_len;
-
-							elem_array = BPy_BMElem_PySeq_As_Array(&bm, value, 0, PY_SSIZE_T_MAX,
-							                                       &elem_array_len, (slot->slot_subtype.elem & BM_ALL_NOLOOP),
-							                                       TRUE, TRUE, slot_name);
-
-							/* error is set above */
-							if (elem_array == NULL) {
-								return NULL;
-							}
+							BLI_assert(slot->slot_subtype.elem & ((BPy_BMElem *)py_val)->ele->head.htype);
 
-							BMO_slot_buffer_alloc(&bmop, bmop.slots_in, slot_name, elem_array_len);
-							memcpy(slot->data.buf, elem_array, sizeof(void *) * elem_array_len);
-							PyMem_FREE(elem_array);
+							PyDict_SetItem(item, py_key, py_val);
+							Py_DECREF(py_key);
+							Py_DECREF(py_val);
 						}
-						else {
-							PyErr_Format(PyExc_TypeError,
-							             "%.200s: keyword \"%.200s\" expected "
-							             "a bmesh sequence, list, (htype, flag) pair, not %.200s",
-							             self->opname, slot_name, Py_TYPE(value)->tp_name);
-							return NULL;
+					}
+					break;
+				}
+				case BMO_OP_SLOT_SUBTYPE_MAP_FLOAT:
+				{
+					item = PyDict_New();
+					if (slot_hash) {
+						GHASH_ITER (hash_iter, slot_hash) {
+							BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
+							BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
+
+							PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
+							PyObject *py_val =  PyFloat_FromDouble(*(float *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
+
+							PyDict_SetItem(item, py_key, py_val);
+							Py_DECREF(py_key);
+							Py_DECREF(py_val);
 						}
 					}
-#undef BPY_BM_GENERIC_MESH_TEST
-
 					break;
 				}
-				case BMO_OP_SLOT_MAPPING:
+				case BMO_OP_SLOT_SUBTYPE_MAP_INT:
 				{
-					/* first check types */
-					if (slot->slot_subtype.map != BMO_OP_SLOT_SUBTYPE_MAP_EMPTY) {
-						if (!PyDict_Check(value)) {
-							PyErr_Format(PyExc_TypeError,
-							             "%.200s: keyword \"%.200s\" expected "
-							             "a dict, not %.200s",
-							             self->opname, slot_name, Py_TYPE(value)->tp_name);
-							return NULL;
+					item = PyDict_New();
+					if (slot_hash) {
+						GHASH_ITER (hash_iter, slot_hash) {
+							BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
+							BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
+
+							PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
+							PyObject *py_val =  PyLong_FromLong(*(int *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
+
+							PyDict_SetItem(item, py_key, py_val);
+							Py_DECREF(py_key);
+							Py_DECREF(py_val);
 						}
 					}
-					else {
-						if (!PySet_Check(value)) {
-							PyErr_Format(PyExc_TypeError,
-							             "%.200s: keyword \"%.200s\" expected "
-							             "a set, not %.200s",
-							             self->opname, slot_name, Py_TYPE(value)->tp_name);
-							return NULL;
+					break;
+				}
+				case BMO_OP_SLOT_SUBTYPE_MAP_BOOL:
+				{
+					item = PyDict_New();
+					if (slot_hash) {
+						GHASH_ITER (hash_iter, slot_hash) {
+							BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
+							BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
+
+							PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
+							PyObject *py_val =  PyBool_FromLong(*(int *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
+
+							PyDict_SetItem(item, py_key, py_val);
+							Py_DECREF(py_key);
+							Py_DECREF(py_val);
 						}
 					}
+					break;
+				}
+				case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY:
+				{
+					item = PySet_New(NULL);
+					if (slot_hash) {
+						GHASH_ITER (hash_iter, slot_hash) {
+							BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
 
-					switch (slot->slot_subtype.map) {
+							PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
 
-						/* this could be a static function */
-#define BPY_BM_MAPPING_KEY_CHECK(arg_key)  \
-						if (!BPy_BMElem_Check(arg_key)) { \
-							PyErr_Format(PyExc_TypeError, \
-							             "%.200s: keyword \"%.200s\" expected " \
-							             "a dict with bmesh element keys, not %.200s", \
-							             self->opname, slot_name, Py_TYPE(arg_key)->tp_name); \
-							return NULL; \
-						} \
-						else if (((BPy_BMGeneric *)arg_key)->bm == NULL) { \
-							PyErr_Format(PyExc_TypeError, \
-							             "%.200s: keyword \"%.200s\" invalidated element key in dict", \
-							             self->opname, slot_name); \
-							return NULL; \
-						} (void)0
-
-
-						case BMO_OP_SLOT_SUBTYPE_MAP_ELEM:
-						{
-							if (PyDict_Size(value) > 0) {
-								PyObject *arg_key, *arg_value;
-								Py_ssize_t arg_pos = 0;
-								while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
-									/* TODO, check the elements come from the right mesh? */
-									BPY_BM_MAPPING_KEY_CHECK(arg_key);
-
-									if (!BPy_BMElem_Check(arg_value)) {
-										PyErr_Format(PyExc_TypeError,
-										             "%.200s: keyword \"%.200s\" expected "
-										             "a dict with bmesh element values, not %.200s",
-										             self->opname, slot_name, Py_TYPE(arg_value)->tp_name);
-										return NULL;
-									}
-									else if (((BPy_BMGeneric *)arg_value)->bm == NULL) {
-										PyErr_Format(PyExc_TypeError,
-										             "%.200s: keyword \"%.200s\" invalidated element value in dict",
-										             self->opname, slot_name);
-										return NULL;
-									}
-
-									BMO_slot_map_elem_insert(&bmop, slot,
-									                         ((BPy_BMElem *)arg_key)->ele, ((BPy_BMElem *)arg_value)->ele);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_FLOAT:
-						{
-							if (PyDict_Size(value) > 0) {
-								PyObject *arg_key, *arg_value;
-								Py_ssize_t arg_pos = 0;
-								while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
-									float value_f;
-									/* TODO, check the elements come from the right mesh? */
-									BPY_BM_MAPPING_KEY_CHECK(arg_key);
-									value_f = PyFloat_AsDouble(arg_value);
-
-									if (value_f == -1.0f && PyErr_Occurred()) {
-										PyErr_Format(PyExc_TypeError,
-										             "%.200s: keyword \"%.200s\" expected "
-										             "a dict with float values, not %.200s",
-										             self->opname, slot_name, Py_TYPE(arg_value)->tp_name);
-										return NULL;
-									}
-
-									BMO_slot_map_float_insert(&bmop, slot,
-									                          ((BPy_BMElem *)arg_key)->ele, value_f);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_INT:
-						{
-							if (PyDict_Size(value) > 0) {
-								PyObject *arg_key, *arg_value;
-								Py_ssize_t arg_pos = 0;
-								while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
-									int value_i;
-									/* TODO, check the elements come from the right mesh? */
-									BPY_BM_MAPPING_KEY_CHECK(arg_key);
-									value_i = PyLong_AsLong(arg_value);
-
-									if (value_i == -1 && PyErr_Occurred()) {
-										PyErr_Format(PyExc_TypeError,
-										             "%.200s: keyword \"%.200s\" expected "
-										             "a dict with int values, not %.200s",
-										             self->opname, slot_name, Py_TYPE(arg_value)->tp_name);
-										return NULL;
-									}
-
-									BMO_slot_map_int_insert(&bmop, slot,
-									                        ((BPy_BMElem *)arg_key)->ele, value_i);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_BOOL:
-						{
-							if (PyDict_Size(value) > 0) {
-								PyObject *arg_key, *arg_value;
-								Py_ssize_t arg_pos = 0;
-								while (PyDict_Next(value, &arg_pos, &arg_key, &arg_value)) {
-									int value_i;
-									/* TODO, check the elements come from the right mesh? */
-									BPY_BM_MAPPING_KEY_CHECK(arg_key);
-									value_i = PyLong_AsLong(arg_value);
-
-									if (value_i == -1 && PyErr_Occurred()) {
-										PyErr_Format(PyExc_TypeError,
-										             "%.200s: keyword \"%.200s\" expected "
-										             "a dict with bool values, not %.200s",
-										             self->opname, slot_name, Py_TYPE(arg_value)->tp_name);
-										return NULL;
-									}
-
-									BMO_slot_map_bool_insert(&bmop, slot,
-									                         ((BPy_BMElem *)arg_key)->ele, value_i != 0);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY:
-						{
-							if (PySet_Size(value) > 0) {
-								PyObject *arg_key;
-								Py_ssize_t arg_pos = 0;
-								Py_ssize_t arg_hash = 0;
-								while (_PySet_NextEntry(value, &arg_pos, &arg_key, &arg_hash)) {
-									/* TODO, check the elements come from the right mesh? */
-									BPY_BM_MAPPING_KEY_CHECK(arg_key);
-
-									BMO_slot_map_empty_insert(&bmop, slot,
-									                         ((BPy_BMElem *)arg_key)->ele);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL:
-						{
-							/* can't convert from these */
-							PyErr_Format(PyExc_NotImplementedError,
-							             "This arguments mapping subtype %d is not supported", slot->slot_subtype);
-							break;
-						}
-#undef BPY_BM_MAPPING_KEY_CHECK
+							PySet_Add(item, py_key);
 
+							Py_DECREF(py_key);
+						}
 					}
+					break;
 				}
-				default:
-					/* TODO --- many others */
-					PyErr_Format(PyExc_NotImplementedError,
-					             "%.200s: keyword \"%.200s\" type %d not working yet!",
-					             self->opname, slot_name, slot->slot_type);
-					return NULL;
+				case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL:
+					/* can't convert from these */
+					item = (Py_INCREF(Py_None), Py_None);
 					break;
 			}
+			break;
+		}
+	}
+	BLI_assert(item != NULL);
+
+	return item;
+}
+
+/**
+ * This is the __call__ for bmesh.ops.xxx()
+ */
+PyObject *BPy_BMO_call(BPy_BMeshOpFunc *self, PyObject *args, PyObject *kw)
+{
+	PyObject *ret;
+	BPy_BMesh *py_bm;
+	BMesh *bm;
+
+	BMOperator bmop;
+
+	if ((PyTuple_GET_SIZE(args) == 1) &&
+	    (py_bm = (BPy_BMesh *)PyTuple_GET_ITEM(args, 0)) &&
+	    (BPy_BMesh_Check(py_bm))
+		)
+	{
+		BPY_BM_CHECK_OBJ(py_bm);
+		bm = py_bm->bm;
+	}
+	else {
+		PyErr_SetString(PyExc_TypeError,
+		                "calling a bmesh operator expects a single BMesh (non keyword) "
+		                "as the first argument");
+		return NULL;
+	}
+
+	/* TODO - error check this!, though we do the error check on attribute access */
+	/* TODO - make flags optional */
+	BMO_op_init(bm, &bmop, BMO_FLAG_DEFAULTS, self->opname);
+
+	if (kw && PyDict_Size(kw) > 0) {
+		/* setup properties, see bpy_rna.c: pyrna_py_to_prop()
+		 * which shares this logic for parsing properties */
+
+		PyObject *key, *value;
+		Py_ssize_t pos = 0;
+		while (PyDict_Next(kw, &pos, &key, &value)) {
+			const char *slot_name = _PyUnicode_AsString(key);
+			BMOpSlot *slot = BMO_slot_get(bmop.slots_in, slot_name);
+
+			if (slot == NULL) {
+				PyErr_Format(PyExc_TypeError,
+				             "%.200s: keyword \"%.200s\" is invalid for this operator",
+				             self->opname, slot_name);
+				return NULL;
+			}
+
+			/* now assign the value */
+			if (bpy_slot_from_py(bm, &bmop, slot, value,
+			                     self->opname, slot_name) == -1)
+			{
+				return NULL;
+			}
 		}
 	}
 
@@ -518,153 +692,10 @@ PyObject *BPy_BMO_call(BPy_BMeshOpFunc *self, PyObject *args, PyObject *kw)
 			// BMOpDefine *op_def = opdefines[bmop.type];
 			// BMOSlotType *slot_type = op_def->slot_types_out[i];
 			BMOpSlot *slot = &bmop.slots_out[i];
-			PyObject *item = NULL;
+			PyObject *item;
 
-			/* keep switch in same order as above */
-			switch (slot->slot_type) {
-				case BMO_OP_SLOT_BOOL:
-					item = PyBool_FromLong((BMO_SLOT_AS_BOOL(slot)));
-					break;
-				case BMO_OP_SLOT_INT:
-					item = PyLong_FromLong(BMO_SLOT_AS_INT(slot));
-					break;
-				case BMO_OP_SLOT_FLT:
-					item = PyFloat_FromDouble((double)BMO_SLOT_AS_FLOAT(slot));
-					break;
-				case BMO_OP_SLOT_MAT:
-					item = Matrix_CreatePyObject((float *)BMO_SLOT_AS_MATRIX(slot), 4, 4, Py_NEW, NULL);
-					break;
-				case BMO_OP_SLOT_VEC:
-					item = Vector_CreatePyObject(BMO_SLOT_AS_VECTOR(slot), slot->len, Py_NEW, NULL);
-					break;
-				case BMO_OP_SLOT_PTR:
-					BLI_assert(0);  /* currently we don't have any pointer return values in use */
-					item = (Py_INCREF(Py_None), Py_None);
-					break;
-				case BMO_OP_SLOT_ELEMENT_BUF:
-				{
-					if (slot->slot_subtype.elem & BMO_OP_SLOT_SUBTYPE_ELEM_IS_SINGLE) {
-						BMHeader *ele = BMO_slot_buffer_get_single(slot);
-						item = ele ? BPy_BMElem_CreatePyObject(bm, ele) : (Py_INCREF(Py_None), Py_None);
-					}
-					else {
-						const int size = slot->len;
-						void **buffer = BMO_SLOT_AS_BUFFER(slot);
-						int j;
-
-						item = PyList_New(size);
-						for (j = 0; j < size; j++) {
-							BMHeader *ele = buffer[i];
-							PyList_SET_ITEM(item, j, BPy_BMElem_CreatePyObject(bm, ele));
-						}
-					}
-					break;
-				}
-				case BMO_OP_SLOT_MAPPING:
-				{
-					GHash *slot_hash = BMO_SLOT_AS_GHASH(slot);
-					GHashIterator hash_iter;
-
-					switch (slot->slot_subtype.map) {
-						case BMO_OP_SLOT_SUBTYPE_MAP_ELEM:
-						{
-							item = PyDict_New();
-							if (slot_hash) {
-								GHASH_ITER (hash_iter, slot_hash) {
-									BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
-									BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
-
-									PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
-									PyObject *py_val =  BPy_BMElem_CreatePyObject(bm, *(void **)BMO_OP_SLOT_MAPPING_DATA(ele_val));
-
-									BLI_assert(slot->slot_subtype.elem & ((BPy_BMElem *)py_val)->ele->head.htype);
-
-									PyDict_SetItem(ret, py_key, py_val);
-									Py_DECREF(py_key);
-									Py_DECREF(py_val);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_FLOAT:
-						{
-							item = PyDict_New();
-							if (slot_hash) {
-								GHASH_ITER (hash_iter, slot_hash) {
-									BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
-									BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
-
-									PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
-									PyObject *py_val =  PyFloat_FromDouble(*(float *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
-
-									PyDict_SetItem(ret, py_key, py_val);
-									Py_DECREF(py_key);
-									Py_DECREF(py_val);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_INT:
-						{
-							item = PyDict_New();
-							if (slot_hash) {
-								GHASH_ITER (hash_iter, slot_hash) {
-									BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
-									BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
-
-									PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
-									PyObject *py_val =  PyLong_FromLong(*(int *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
-
-									PyDict_SetItem(ret, py_key, py_val);
-									Py_DECREF(py_key);
-									Py_DECREF(py_val);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_BOOL:
-						{
-							item = PyDict_New();
-							if (slot_hash) {
-								GHASH_ITER (hash_iter, slot_hash) {
-									BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
-									BMOElemMapping *ele_val = BLI_ghashIterator_getValue(&hash_iter);
-
-									PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
-									PyObject *py_val =  PyBool_FromLong(*(int *)BMO_OP_SLOT_MAPPING_DATA(ele_val));
-
-									PyDict_SetItem(ret, py_key, py_val);
-									Py_DECREF(py_key);
-									Py_DECREF(py_val);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_EMPTY:
-						{
-							item = PySet_New(NULL);
-							if (slot_hash) {
-								GHASH_ITER (hash_iter, slot_hash) {
-									BMHeader       *ele_key = BLI_ghashIterator_getKey(&hash_iter);
-
-									PyObject *py_key =  BPy_BMElem_CreatePyObject(bm,  ele_key);
-
-									PySet_Add(item, py_key);
-
-									Py_DECREF(py_key);
-								}
-							}
-							break;
-						}
-						case BMO_OP_SLOT_SUBTYPE_MAP_INTERNAL:
-							/* can't convert from these */
-							item = (Py_INCREF(Py_None), Py_None);
-							break;
-					}
-					break;
-				}
-			}
-			BLI_assert(item != NULL);
+			/* this function doesn't throw exceptions */
+			item = bpy_slot_to_py(bm, slot);
 			if (item == NULL) {
 				item = (Py_INCREF(Py_None), Py_None);
 			}