python · vstinner · Nov 9, 2020 · Nov 9, 2020
diff --git a/Doc/c-api/tuple.rst b/Doc/c-api/tuple.rst
@@ -54,10 +54,19 @@ Tuple Objects
    no error checking is performed.
 
 
+.. c:function:: PyObject* PyTuple_GetItemRef(PyObject *p, Py_ssize_t pos)
+
+   Return a :term:`strong reference` to the object at position *pos* in the
+   tuple pointed to by *p*.  If *pos* is out of bounds, return ``NULL`` and set
+   an :exc:`IndexError` exception.
+
+   .. versionadded:: 3.10
+
+
 .. c:function:: PyObject* PyTuple_GetItem(PyObject *p, Py_ssize_t pos)
 
-   Return the object at position *pos* in the tuple pointed to by *p*.  If *pos* is
-   out of bounds, return ``NULL`` and set an :exc:`IndexError` exception.
+   Similar to :c:func:`PyTuple_GetItemRef`, but return a :term:`borrowed
+   reference`.
 
 
 .. c:function:: PyObject* PyTuple_GET_ITEM(PyObject *p, Py_ssize_t pos)

diff --git a/Doc/data/refcounts.dat b/Doc/data/refcounts.dat
@@ -2251,6 +2251,10 @@ PyTuple_GetItem:PyObject*::0:
 PyTuple_GetItem:PyObject*:p:0:
 PyTuple_GetItem:Py_ssize_t:pos::
 
+PyTuple_GetItemRef:PyObject*::+1:
+PyTuple_GetItemRef:PyObject*:p:0:
+PyTuple_GetItemRef:Py_ssize_t:pos::
+
 PyTuple_GET_SIZE:Py_ssize_t:::
 PyTuple_GET_SIZE:PyObject*:p:0:
 

diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst
@@ -429,6 +429,10 @@ New Features
   slot.
   (Contributed by Hai Shi in :issue:`41832`.)
 
+* Added :c:func:`PyTuple_GetItemRef` function: similar to
+  :c:func:`PyTuple_GetItem`, but return a :term:`strong reference`.
+  (Contributed by Victor Stinner in :issue:`42262`.)
+
 
 Porting to Python 3.10
 ----------------------

diff --git a/Include/tupleobject.h b/Include/tupleobject.h
@@ -30,6 +30,7 @@ PyAPI_DATA(PyTypeObject) PyTupleIter_Type;
 PyAPI_FUNC(PyObject *) PyTuple_New(Py_ssize_t size);
 PyAPI_FUNC(Py_ssize_t) PyTuple_Size(PyObject *);
 PyAPI_FUNC(PyObject *) PyTuple_GetItem(PyObject *, Py_ssize_t);
+PyAPI_FUNC(PyObject *) PyTuple_GetItemRef(PyObject *, Py_ssize_t);
 PyAPI_FUNC(int) PyTuple_SetItem(PyObject *, Py_ssize_t, PyObject *);
 PyAPI_FUNC(PyObject *) PyTuple_GetSlice(PyObject *, Py_ssize_t, Py_ssize_t);
 PyAPI_FUNC(PyObject *) PyTuple_Pack(Py_ssize_t, ...);

diff --git a/Misc/NEWS.d/next/C API/2020-11-09-12-10-23.bpo-42294.Kt0LG9.rst b/Misc/NEWS.d/next/C API/2020-11-09-12-10-23.bpo-42294.Kt0LG9.rst
@@ -0,0 +1,3 @@
+Added :c:func:`PyTuple_GetItemRef` function: similar to
+:c:func:`PyTuple_GetItem`, but return a :term:`strong reference`.
+Patch by Victor Stinner.
@@ -3264,34 +3264,19 @@ iso_calendar_date_reduce(PyObject *self, PyObject *Py_UNUSED(ignored))
 static PyObject *
 iso_calendar_date_year(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject *year = PyTuple_GetItem((PyObject *)self, 0);
-    if (year == NULL) {
-        return NULL;
-    }
-    Py_INCREF(year);
-    return year;
+    return PyTuple_GetItemRef((PyObject *)self, 0);
 }
 
 static PyObject *
 iso_calendar_date_week(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject *week = PyTuple_GetItem((PyObject *)self, 1);
-    if (week == NULL) {
-        return NULL;
-    }
-    Py_INCREF(week);
-    return week;
+    return PyTuple_GetItemRef((PyObject *)self, 1);
 }
 
 static PyObject *
 iso_calendar_date_weekday(PyDateTime_IsoCalendarDate *self, void *unused)
 {
-    PyObject *weekday = PyTuple_GetItem((PyObject *)self, 2);
-    if (weekday == NULL) {
-        return NULL;
-    }
-    Py_INCREF(weekday);
-    return weekday;
+    return PyTuple_GetItemRef((PyObject *)self, 2);
 }
 
 static PyGetSetDef iso_calendar_date_getset[] = {

@@ -74,9 +74,7 @@ pysqlite_row_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 
 PyObject* pysqlite_row_item(pysqlite_Row* self, Py_ssize_t idx)
 {
-   PyObject* item = PyTuple_GetItem(self->data, idx);
-   Py_XINCREF(item);
-   return item;
+   return PyTuple_GetItemRef(self->data, idx);
 }
 
 static int
@@ -111,18 +109,16 @@ PyObject* pysqlite_row_subscript(pysqlite_Row* self, PyObject* idx)
 {
     Py_ssize_t _idx;
     Py_ssize_t nitems, i;
-    PyObject* item;
 
     if (PyLong_Check(idx)) {
         _idx = PyNumber_AsSsize_t(idx, PyExc_IndexError);
         if (_idx == -1 && PyErr_Occurred())
             return NULL;
         if (_idx < 0)
            _idx += PyTuple_GET_SIZE(self->data);
-        item = PyTuple_GetItem(self->data, _idx);
-        Py_XINCREF(item);
-        return item;
-    } else if (PyUnicode_Check(idx)) {
+        return PyTuple_GetItemRef(self->data, _idx);
+    }
+    else if (PyUnicode_Check(idx)) {
         nitems = PyTuple_Size(self->description);
 
         for (i = 0; i < nitems; i++) {
@@ -135,9 +131,7 @@ PyObject* pysqlite_row_subscript(pysqlite_Row* self, PyObject* idx)
             }
             if (eq) {
                 /* found item */
-                item = PyTuple_GetItem(self->data, i);
-                Py_INCREF(item);
-                return item;
+                return PyTuple_GetItemRef(self->data, i);
             }
         }
 

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
@@ -187,7 +187,15 @@ PyTuple_GetItem(PyObject *op, Py_ssize_t i)
         PyErr_SetString(PyExc_IndexError, "tuple index out of range");
         return NULL;
     }
-    return ((PyTupleObject *)op) -> ob_item[i];
+    return PyTuple_GET_ITEM(op, i);
+}
+
+PyObject *
+PyTuple_GetItemRef(PyObject *op, Py_ssize_t i)
+{
+    PyObject *item = PyTuple_GetItem(op, i);
+    // On a newly created tuple, an item can still be NULL
+    return Py_XNewRef(item);
 }
 
 int

@@ -539,6 +539,7 @@ EXPORT_FUNC(PyThreadState_Swap)
 EXPORT_FUNC(PyTraceBack_Here)
 EXPORT_FUNC(PyTraceBack_Print)
 EXPORT_FUNC(PyTuple_GetItem)
+EXPORT_FUNC(PyTuple_GetItemRef)
 EXPORT_FUNC(PyTuple_GetSlice)
 EXPORT_FUNC(PyTuple_New)
 EXPORT_FUNC(PyTuple_Pack)

@@ -1091,9 +1091,9 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
 /* Tuple access macros */
 
 #ifndef Py_DEBUG
-#define GETITEM(v, i) PyTuple_GET_ITEM((PyTupleObject *)(v), (i))
+#  define GETITEM(v, i) PyTuple_GET_ITEM((PyTupleObject *)(v), (i))
 #else
-#define GETITEM(v, i) PyTuple_GetItem((v), (i))
+#  define GETITEM(v, i) PyTuple_GetItem((v), (i))
 #endif
 
 /* Code access macros */