PEP 205, Weak References -- initial checkin.

2 files changed, 28 insertions, 0 deletions

diff --git a/Objects/classobject.c b/Objects/classobject.c
index 218e031..bb17df1 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -515,6 +515,10 @@ instance_dealloc(register PyInstanceObject *inst)
 #ifdef Py_REF_DEBUG
 	extern long _Py_RefTotal;
 #endif
+
+	if (!PyObject_ClearWeakRefs((PyObject *) inst))
+		return;
+
 	/* Temporarily resurrect the object. */
 #ifdef Py_TRACE_REFS
 #ifndef Py_REF_DEBUG
@@ -1771,6 +1775,7 @@ PyTypeObject PyInstance_Type = {
 	(traverseproc)instance_traverse,	/* tp_traverse */
 	0,					/* tp_clear */
 	instance_richcompare,			/* tp_richcompare */
+ 	offsetof(PyInstanceObject, in_weakreflist) /* tp_weaklistoffset */
 };
 
 
diff --git a/Objects/object.c b/Objects/object.c
index 40c939a..a4c9f08 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -100,6 +100,10 @@ PyObject_Init(PyObject *op, PyTypeObject *tp)
 	/* Any changes should be reflected in PyObject_INIT (objimpl.h) */
 	op->ob_type = tp;
 	_Py_NewReference(op);
+	if (PyType_SUPPORTS_WEAKREFS(tp)) {
+		PyObject **weaklist = PyObject_GET_WEAKREFS_LISTPTR(op);
+		*weaklist = NULL;
+	}
 	return op;
 }
 
@@ -119,6 +123,10 @@ PyObject_InitVar(PyVarObject *op, PyTypeObject *tp, int size)
 	op->ob_size = size;
 	op->ob_type = tp;
 	_Py_NewReference((PyObject *)op);
+	if (PyType_SUPPORTS_WEAKREFS(tp)) {
+		PyObject **weaklist = PyObject_GET_WEAKREFS_LISTPTR(op);
+		*weaklist = NULL;
+	}
 	return op;
 }
 
@@ -1458,6 +1466,21 @@ PyObject_Free(void *p)
 }
 
 
+/* Hook to clear up weak references only once the _weakref module is
+   imported.  We use a dummy implementation to simplify the code at each
+   call site instead of requiring a test for NULL.
+*/
+
+static int
+empty_clear_weak_refs(PyObject *o)
+{
+    return 1;
+}
+
+int (*PyObject_ClearWeakRefs)(PyObject *) = empty_clear_weak_refs;
+
+
+
 /* These methods are used to control infinite recursion in repr, str, print,
    etc.  Container objects that may recursively contain themselves,
    e.g. builtin dictionaries and lists, should used Py_ReprEnter() and