Change the getset type to take an optional third function argument:
the delete function. (Question: should the attribute name also be
recorded in the getset object? That makes the protocol more work, but
may give us better error messages.)
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index c29dd83..efed1c0 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -868,6 +868,7 @@
PyObject_HEAD
PyObject *get;
PyObject *set;
+ PyObject *del;
} getsetobject;
static void
@@ -877,6 +878,7 @@
Py_XDECREF(gs->get);
Py_XDECREF(gs->set);
+ Py_XDECREF(gs->del);
self->ob_type->tp_free(self);
}
@@ -900,16 +902,23 @@
getset_descr_set(PyObject *self, PyObject *obj, PyObject *value)
{
getsetobject *gs = (getsetobject *)self;
- PyObject *res;
+ PyObject *func, *res;
- if (gs->set == NULL) {
- PyErr_SetString(PyExc_AttributeError, "unsettable attribute");
+ if (value == NULL)
+ func = gs->del;
+ else
+ func = gs->set;
+ if (func == NULL) {
+ PyErr_SetString(PyExc_AttributeError,
+ value == NULL ?
+ "can't delete attribute" :
+ "can't set attribute");
return -1;
}
if (value == NULL)
- res = PyObject_CallFunction(gs->set, "(O)", obj);
+ res = PyObject_CallFunction(func, "(O)", obj);
else
- res = PyObject_CallFunction(gs->set, "(OO)", obj, value);
+ res = PyObject_CallFunction(func, "(OO)", obj, value);
if (res == NULL)
return -1;
Py_DECREF(res);
@@ -919,10 +928,10 @@
static int
getset_init(PyObject *self, PyObject *args, PyObject *kwds)
{
- PyObject *get = NULL, *set = NULL;
+ PyObject *get = NULL, *set = NULL, *del = NULL;
getsetobject *gs = (getsetobject *)self;
- if (!PyArg_ParseTuple(args, "|OO:getset.__init__", &get, &set))
+ if (!PyArg_ParseTuple(args, "|OOO:getset.__init__", &get, &set, &del))
return -1;
if (get == Py_None)
get = NULL;
@@ -930,18 +939,21 @@
set = NULL;
Py_XINCREF(get);
Py_XINCREF(set);
+ Py_XINCREF(del);
gs->get = get;
gs->set = set;
+ gs->del = del;
return 0;
}
static char getset_doc[] =
-"getset([getfunc[, setfunc]]) -> getset attribute\n"
+"getset([getfunc[, setfunc[, delfunc]]]) -> getset attribute\n"
"Typical use to define a managed attribute x of C instances:\n"
"class C(object):\n"
" def getx(self): return self.__x\n"
" def setx(self, value): self.__x = value\n"
-" x = getset(getx, setx)";
+" def delx(self): del self.__x\n"
+" x = getset(getx, setx, delx)";
PyTypeObject PyGetSet_Type = {
PyObject_HEAD_INIT(&PyType_Type)