patch [#26215] Python weak reference (weakref) support for game objects

by Alex Fraser (z0r)

2 files changed, 34 insertions, 10 deletions

diff --git a/source/gameengine/Expressions/PyObjectPlus.cpp b/source/gameengine/Expressions/PyObjectPlus.cpp
index a3c1e24cdf6..84d6a1cba4b 100644
--- a/source/gameengine/Expressions/PyObjectPlus.cpp
+++ b/source/gameengine/Expressions/PyObjectPlus.cpp
@@ -108,19 +108,26 @@ void PyObjectPlus::InvalidateProxy()		// check typename of each parent
 
 PyTypeObject PyObjectPlus::Type = {
 	PyVarObject_HEAD_INIT(NULL, 0)
-	"PyObjectPlus",			/*tp_name*/
+	"PyObjectPlus",					/*tp_name*/
 	sizeof(PyObjectPlus_Proxy),		/*tp_basicsize*/
-	0,				/*tp_itemsize*/
+	0,								/*tp_itemsize*/
 	/* methods */
-	py_base_dealloc,
-	0,
-	0,
-	0,
+	py_base_dealloc,				/* tp_dealloc */
+	0,								/* printfunc tp_print; */
+	0,								/* getattrfunc tp_getattr; */
+	0,								/* setattrfunc tp_setattr; */
+	0,								/* tp_compare */ /* DEPRECATED in python 3.0! */
+	py_base_repr,					/* tp_repr */
+	0,0,0,0,0,0,0,0,0,				/* Method suites for standard classes */
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,/* long tp_flags; */
+	0,0,0,0,
+	/* weak reference enabler */
+#ifdef USE_WEAKREFS
+	offsetof(PyObjectPlus_Proxy, in_weakreflist),	/* long tp_weaklistoffset; */
+#else
 	0,
-	py_base_repr,
-	0,0,0,0,0,0,0,0,0,
-	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
-	0,0,0,0,0,0,0,
+#endif
+	0,0,
 	Methods,
 	0,
 	0,
@@ -209,8 +216,16 @@ PyObject * PyObjectPlus::py_base_new(PyTypeObject *type, PyObject *args, PyObjec
 	return (PyObject *)ret;
 }
 
+/**
+  * @param self A PyObjectPlus_Proxy
+  */
 void PyObjectPlus::py_base_dealloc(PyObject *self)				// python wrapper
 {
+#ifdef USE_WEAKREFS
+	if (BGE_PROXY_WKREF(self) != NULL)
+		PyObject_ClearWeakRefs((PyObject *) self);
+#endif
+
 	if (BGE_PROXY_PYREF(self)) {
 		PyObjectPlus *self_plus= BGE_PROXY_REF(self);
 		if(self_plus) {
@@ -1107,6 +1122,7 @@ PyObject *PyObjectPlus::GetProxyPlus_Ext(PyObjectPlus *self, PyTypeObject *tp, v
 		self->m_proxy = reinterpret_cast<PyObject *>PyObject_NEW( PyObjectPlus_Proxy, tp);
 		BGE_PROXY_PYOWNS(self->m_proxy) = false;
 		BGE_PROXY_PYREF(self->m_proxy) = true;
+		BGE_PROXY_WKREF(self->m_proxy) = NULL;
 	}
 	//PyObject_Print(self->m_proxy, stdout, 0);
 	//printf("ref %d\n", self->m_proxy->ob_refcnt);
@@ -1127,6 +1143,7 @@ PyObject *PyObjectPlus::NewProxyPlus_Ext(PyObjectPlus *self, PyTypeObject *tp, v
 		BGE_PROXY_PYOWNS(proxy) = py_owns;
 		BGE_PROXY_REF(proxy) = NULL; 
 		BGE_PROXY_PTR(proxy) = ptr;
+		BGE_PROXY_WKREF(self->m_proxy) = NULL;
 		return proxy;
 	}
 	if (self->m_proxy)
diff --git a/source/gameengine/Expressions/PyObjectPlus.h b/source/gameengine/Expressions/PyObjectPlus.h
index 12ae31f6c82..315a328317d 100644
--- a/source/gameengine/Expressions/PyObjectPlus.h
+++ b/source/gameengine/Expressions/PyObjectPlus.h
@@ -31,6 +31,9 @@
  *  \ingroup expressions
  */
 
+/* for now keep weakrefs optional */
+#define USE_WEAKREFS
+
 #ifndef _adr_py_lib_h_				// only process once,
 #define _adr_py_lib_h_				// even if multiply included
 
@@ -95,6 +98,9 @@ typedef struct PyObjectPlus_Proxy {
 	void *ptr;					// optional pointer to generic structure, the structure holds no reference to this proxy
 	bool py_owns;		// true if the object pointed by ref should be deleted when the proxy is deleted
 	bool py_ref;		// true if proxy is connected to a GE object (ref is used)
+#ifdef USE_WEAKREFS
+	PyObject *in_weakreflist; // weak reference enabler
+#endif
 } PyObjectPlus_Proxy;
 
 #define BGE_PROXY_ERROR_MSG "Blender Game Engine data has been freed, cannot use this python variable"
@@ -102,6 +108,7 @@ typedef struct PyObjectPlus_Proxy {
 #define BGE_PROXY_PTR(_self) (((PyObjectPlus_Proxy *)_self)->ptr)
 #define BGE_PROXY_PYOWNS(_self) (((PyObjectPlus_Proxy *)_self)->py_owns)
 #define BGE_PROXY_PYREF(_self) (((PyObjectPlus_Proxy *)_self)->py_ref)
+#define BGE_PROXY_WKREF(_self) (((PyObjectPlus_Proxy *)_self)->in_weakreflist)
 
 /* Note, sometimes we dont care what BGE type this is as long as its a proxy */
 #define BGE_PROXY_CHECK_TYPE(_type) ((_type)->tp_dealloc == PyObjectPlus::py_base_dealloc)