Clarifying code rearrangement and comments by David Abrahams. I've
got to admit that I haven't reviewed this carefully, but it looks okay
from 30,000 views, and doesn't break anything. (SF patch 536407.)
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index a3fefe6..c369ff7 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -1236,8 +1236,8 @@
type_getattro(PyTypeObject *type, PyObject *name)
{
PyTypeObject *metatype = type->ob_type;
- PyObject *descr, *res;
- descrgetfunc f;
+ PyObject *meta_attribute, *attribute;
+ descrgetfunc meta_get;
/* Initialize this type (we'll assume the metatype is initialized) */
if (type->tp_dict == NULL) {
@@ -1245,40 +1245,58 @@
return NULL;
}
- /* Get a descriptor from the metatype */
- descr = _PyType_Lookup(metatype, name);
- f = NULL;
- if (descr != NULL) {
- f = descr->ob_type->tp_descr_get;
- if (f != NULL && PyDescr_IsData(descr))
- return f(descr,
- (PyObject *)type, (PyObject *)metatype);
+ /* No readable descriptor found yet */
+ meta_get = NULL;
+
+ /* Look for the attribute in the metatype */
+ meta_attribute = _PyType_Lookup(metatype, name);
+
+ if (meta_attribute != NULL) {
+ meta_get = meta_attribute->ob_type->tp_descr_get;
+
+ if (meta_get != NULL && PyDescr_IsData(meta_attribute)) {
+ /* Data descriptors implement tp_descr_set to intercept
+ * writes. Assume the attribute is not overridden in
+ * type's tp_dict (and bases): call the descriptor now.
+ */
+ return meta_get(meta_attribute, (PyObject *)type,
+ (PyObject *)metatype);
+ }
}
- /* Look in tp_dict of this type and its bases */
- res = _PyType_Lookup(type, name);
- if (res != NULL) {
- f = res->ob_type->tp_descr_get;
- if (f != NULL)
- return f(res, (PyObject *)NULL, (PyObject *)type);
- Py_INCREF(res);
- return res;
+ /* No data descriptor found on metatype. Look in tp_dict of this
+ * type and its bases */
+ attribute = _PyType_Lookup(type, name);
+ if (attribute != NULL) {
+ /* Implement descriptor functionality, if any */
+ descrgetfunc local_get = attribute->ob_type->tp_descr_get;
+ if (local_get != NULL) {
+ /* NULL 2nd argument indicates the descriptor was
+ * found on the target object itself (or a base) */
+ return local_get(attribute, (PyObject *)NULL,
+ (PyObject *)type);
+ }
+
+ Py_INCREF(attribute);
+ return attribute;
}
- /* Use the descriptor from the metatype */
- if (f != NULL) {
- res = f(descr, (PyObject *)type, (PyObject *)metatype);
- return res;
- }
- if (descr != NULL) {
- Py_INCREF(descr);
- return descr;
+ /* No attribute found in local __dict__ (or bases): use the
+ * descriptor from the metatype, if any */
+ if (meta_get != NULL)
+ return meta_get(meta_attribute, (PyObject *)type,
+ (PyObject *)metatype);
+
+ /* If an ordinary attribute was found on the metatype, return it now */
+ if (meta_attribute != NULL) {
+ Py_INCREF(meta_attribute);
+ return meta_attribute;
}
/* Give up */
PyErr_Format(PyExc_AttributeError,
- "type object '%.50s' has no attribute '%.400s'",
- type->tp_name, PyString_AS_STRING(name));
+ "type object '%.50s' has no attribute '%.400s'",
+ type->tp_name, PyString_AS_STRING(name));
return NULL;
}