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Address SF patch #480716 as well as related issues.

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SF patch #480716 by Greg Chapman fixes the problem that super's
__get__ method always returns an instance of super, even when the
instance whose __get__ method is called is an instance of a subclass
of super.

Other issues fixed:

- super(C, C()).__class__ would return the __class__ attribute of C()
  rather than the __class__ attribute of the super object.  This is
  confusing.  To fix this, I decided to change the semantics of super
  so that it only applies to code attributes, not to data attributes.
  After all, overriding data attributes is not supported anyway.

- While super(C, x) carefully checked that x is an instance of C,
  super(C).__get__(x) made no such check, allowing for a loophole.
  This is now fixed.
This commit is contained in:
Guido van Rossum 2001-12-03 15:38:28 +00:00
parent 22f9c6ddb8
commit 5b443c6282
2 changed files with 87 additions and 18 deletions
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53
Objects/typeobject.c
View file

@ -3929,7 +3929,7 @@ super_getattro(PyObject *self, PyObject *name)
else
continue;
res = PyDict_GetItem(dict, name);
if (res != NULL) {
if (res != NULL && !PyDescr_IsData(res)) {
Py_INCREF(res);
f = res->ob_type->tp_descr_get;
if (f != NULL) {
@ -3944,6 +3944,21 @@ super_getattro(PyObject *self, PyObject *name)
return PyObject_GenericGetAttr(self, name);
}
static int
supercheck(PyTypeObject *type, PyObject *obj)
{
if (!PyType_IsSubtype(obj->ob_type, type) &&
!(PyType_Check(obj) &&
PyType_IsSubtype((PyTypeObject *)obj, type))) {
PyErr_SetString(PyExc_TypeError,
"super(type, obj): "
"obj must be an instance or subtype of type");
return -1;
}
else
return 0;
}
static PyObject *
super_descr_get(PyObject *self, PyObject *obj, PyObject *type)
{
@ -3955,14 +3970,25 @@ super_descr_get(PyObject *self, PyObject *obj, PyObject *type)
Py_INCREF(self);
return self;
}
new = (superobject *)PySuper_Type.tp_new(&PySuper_Type, NULL, NULL);
if (new == NULL)
return NULL;
Py_INCREF(su->type);
Py_INCREF(obj);
new->type = su->type;
new->obj = obj;
return (PyObject *)new;
if (su->ob_type != &PySuper_Type)
/* If su is an instance of a subclass of super,
call its type */
return PyObject_CallFunction((PyObject *)su->ob_type,
"OO", su->type, obj);
else {
/* Inline the common case */
if (supercheck(su->type, obj) < 0)
return NULL;
new = (superobject *)PySuper_Type.tp_new(&PySuper_Type,
NULL, NULL);
if (new == NULL)
return NULL;
Py_INCREF(su->type);
Py_INCREF(obj);
new->type = su->type;
new->obj = obj;
return (PyObject *)new;
}
}
static int
@ -3976,15 +4002,8 @@ super_init(PyObject *self, PyObject *args, PyObject *kwds)
return -1;
if (obj == Py_None)
obj = NULL;
if (obj != NULL &&
!PyType_IsSubtype(obj->ob_type, type) &&
!(PyType_Check(obj) &&
PyType_IsSubtype((PyTypeObject *)obj, type))) {
PyErr_SetString(PyExc_TypeError,
"super(type, obj): "
"obj must be an instance or subtype of type");
if (obj != NULL && supercheck(type, obj) < 0)
return -1;
}
Py_INCREF(type);
Py_XINCREF(obj);
su->type = type;