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Add 'super', another new object type with magical properties.

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super(type) -> unbound super object
super(type, obj) -> bound super object; requires isinstance(obj, type)

Typical use to call a cooperative superclass method:

class C(B):
    def meth(self, arg):
        super(C, self).meth(arg);
This commit is contained in:
Guido van Rossum 2001-08-24 16:47:00 +00:00
parent 76f0cb85c2
commit 705f0f5a91
1 changed files with 155 additions and 0 deletions
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155
Objects/typeobject.c
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@ -2998,3 +2998,158 @@ override_slots(PyTypeObject *type, PyObject *dict)
TPSLOT("__init__", tp_init, slot_tp_init);
TPSLOT("__new__", tp_new, slot_tp_new);
}
/* Cooperative 'super' */
typedef struct {
PyObject_HEAD
PyObject *type;
PyObject *obj;
} superobject;
static void
super_dealloc(PyObject *self)
{
superobject *su = (superobject *)self;
Py_XDECREF(su->obj);
Py_XDECREF(su->type);
self->ob_type->tp_free(self);
}
static PyObject *
super_getattro(PyObject *self, PyObject *name)
{
superobject *su = (superobject *)self;
if (su->obj != NULL) {
PyObject *mro, *res, *tmp;
descrgetfunc f;
int i, n;
mro = ((PyTypeObject *)(su->obj->ob_type))->tp_mro;
assert(mro != NULL && PyTuple_Check(mro));
n = PyTuple_GET_SIZE(mro);
for (i = 0; i < n; i++) {
if (su->type == PyTuple_GET_ITEM(mro, i))
break;
}
assert(i < n);
i++;
res = NULL;
for (; i < n; i++) {
tmp = PyTuple_GET_ITEM(mro, i);
assert(PyType_Check(tmp));
res = PyDict_GetItem(
((PyTypeObject *)tmp)->tp_defined, name);
if (res != NULL) {
Py_INCREF(res);
f = res->ob_type->tp_descr_get;
if (f != NULL) {
tmp = f(res, su->obj, res);
Py_DECREF(res);
res = tmp;
}
return res;
}
}
}
return PyObject_GenericGetAttr(self, name);
}
static PyObject *
super_descr_get(PyObject *self, PyObject *obj, PyObject *type)
{
superobject *su = (superobject *)self;
superobject *new;
if (obj == NULL || obj == Py_None || su->obj != NULL) {
/* Not binding to an object, or already bound */
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;
}
static int
super_init(PyObject *self, PyObject *args, PyObject *kwds)
{
superobject *su = (superobject *)self;
PyObject *type, *obj = NULL;
if (!PyArg_ParseTuple(args, "O!|O:super", &PyType_Type, &type, &obj))
return -1;
if (obj == Py_None)
obj = NULL;
if (obj != NULL && !PyType_IsSubtype(obj->ob_type,
(PyTypeObject *)type)) {
PyErr_SetString(PyExc_TypeError,
"super(type, obj) requires isinstance(obj, type)");
return -1;
}
Py_INCREF(type);
Py_XINCREF(obj);
su->type = type;
su->obj = obj;
return 0;
}
static char super_doc[] =
"super(type) -> unbound super object\n"
"super(type, obj) -> bound super object; requires isinstance(obj, type)\n"
"Typical use to call a cooperative superclass method:\n"
"class C(B):\n"
" def meth(self, arg):\n"
" super(C, self).meth(arg)";
PyTypeObject PySuper_Type = {
PyObject_HEAD_INIT(&PyType_Type)
0, /* ob_size */
"super", /* tp_name */
sizeof(superobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
super_dealloc, /* 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 */
super_getattro, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
super_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
0, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
super_descr_get, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
super_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
PyType_GenericNew, /* tp_new */
_PyObject_Del, /* tp_free */
};