From 19ff51ae75914c2226888ac1a3ffecdc590d0ec7 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Mon, 3 Jan 2011 12:47:01 +0100
Subject: [PATCH] The cursor is weakly referenceable

---
 NEWS-2.3              |  2 +-
 psycopg/cursor.h      |  2 ++
 psycopg/cursor_type.c | 12 +++++++++---
 tests/test_cursor.py  |  7 +++++++
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/NEWS-2.3 b/NEWS-2.3
index 82b87594..a2096bac 100644
--- a/NEWS-2.3
+++ b/NEWS-2.3
@@ -6,7 +6,7 @@ What's new in psycopg 2.3.3
   - Added `register_composite()` function to cast PostgreSQL composite types
     into Python tuples/namedtuples.
   - The build script refuses to guess values if pg_config is not found.
-  - Connections are weakly referenceable.
+  - Connections and cursors are weakly referenceable.
 
 * Bug fixes:
 
diff --git a/psycopg/cursor.h b/psycopg/cursor.h
index 107ddb3a..96a133fa 100644
--- a/psycopg/cursor.h
+++ b/psycopg/cursor.h
@@ -81,6 +81,8 @@ typedef struct {
     PyObject *string_types;   /* a set of typecasters for string types */
     PyObject *binary_types;   /* a set of typecasters for binary types */
 
+    PyObject *weakreflist;    /* list of weak references */
+
 } cursorObject;
 
 /* C-callable functions in cursor_int.c and cursor_ext.c */
diff --git a/psycopg/cursor_type.c b/psycopg/cursor_type.c
index b531ad3e..be22e34f 100644
--- a/psycopg/cursor_type.c
+++ b/psycopg/cursor_type.c
@@ -1642,6 +1642,7 @@ cursor_setup(cursorObject *self, connectionObject *conn, const char *name)
 
     self->string_types = NULL;
     self->binary_types = NULL;
+    self->weakreflist = NULL;
 
     Py_INCREF(Py_None);
     self->description = Py_None;
@@ -1667,7 +1668,11 @@ static void
 cursor_dealloc(PyObject* obj)
 {
     cursorObject *self = (cursorObject *)obj;
-    
+
+    if (self->weakreflist) {
+        PyObject_ClearWeakRefs(obj);
+    }
+
     PyObject_GC_UnTrack(self);
 
     if (self->name) PyMem_Free(self->name);
@@ -1769,14 +1774,15 @@ PyTypeObject cursorType = {
     0,          /*tp_as_buffer*/
 
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_ITER |
-      Py_TPFLAGS_HAVE_GC, /*tp_flags*/
+      Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_WEAKREFS ,
+                /*tp_flags*/
     cursorType_doc, /*tp_doc*/
 
     (traverseproc)cursor_traverse, /*tp_traverse*/
     0,          /*tp_clear*/
 
     0,          /*tp_richcompare*/
-    0,          /*tp_weaklistoffset*/
+    offsetof(cursorObject, weakreflist), /*tp_weaklistoffset*/
 
     cursor_iter, /*tp_iter*/
     cursor_next, /*tp_iternext*/
diff --git a/tests/test_cursor.py b/tests/test_cursor.py
index ad458702..e5dd39b9 100644
--- a/tests/test_cursor.py
+++ b/tests/test_cursor.py
@@ -99,6 +99,13 @@ class CursorTests(unittest.TestCase):
         curs2 = self.conn.cursor()
         self.assertEqual("foofoo", curs2.cast(705, 'foo'))
 
+    def test_weakref(self):
+        from weakref import ref
+        curs = self.conn.cursor()
+        w = ref(curs)
+        del curs
+        self.assert_(w() is None)
+
 
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)