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gh-115754: Get singletons by function calls in lmited C API 3.13
In the limited C API version 3.13, getting Py_None, Py_False, Py_True, Py_Ellipsis and Py_NotImplemented singletons is now implemented as function calls at the stable ABI level to hide implementation details. Getting these constants still return borrowed references.
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‎Doc/whatsnew/3.13.rst‎

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@@ -1645,6 +1645,11 @@ New Features
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between native integer types and Python :class:`int` objects.
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(Contributed by Steve Dower in :gh:`111140`.)
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* In the limited C API version 3.13, getting ``Py_None``, ``Py_False``,
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``Py_True``, ``Py_Ellipsis`` and ``Py_NotImplemented`` singletons is now
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implemented as function calls at the stable ABI level to hide implementation
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details. Getting these constants still return borrowed references.
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(Contributed by Victor Stinner in :gh:`115754`.)
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Porting to Python 3.13
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----------------------

‎Include/boolobject.h‎

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@@ -16,10 +16,17 @@ extern "C" {
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/* Don't use these directly */
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PyAPI_DATA(PyLongObject) _Py_FalseStruct;
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PyAPI_DATA(PyLongObject) _Py_TrueStruct;
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PyAPI_FUNC(PyObject*) _Py_GetFalse(void);
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PyAPI_FUNC(PyObject*) _Py_GetTrue(void);
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030D0000
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# define Py_False _Py_GetFalse()
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# define Py_True _Py_GetTrue()
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#else
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# define Py_False _PyObject_CAST(&_Py_FalseStruct)
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# define Py_True _PyObject_CAST(&_Py_TrueStruct)
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#endif
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/* Use these macros */
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#define Py_False _PyObject_CAST(&_Py_FalseStruct)
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#define Py_True _PyObject_CAST(&_Py_TrueStruct)
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// Test if an object is the True singleton, the same as "x is True" in Python.
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PyAPI_FUNC(int) Py_IsTrue(PyObject *x);

‎Include/object.h‎

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@@ -1070,7 +1070,13 @@ _Py_NoneStruct is an object of undefined type which can be used in contexts
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where NULL (nil) is not suitable (since NULL often means 'error').
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*/
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PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
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#define Py_None (&_Py_NoneStruct)
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PyAPI_FUNC(PyObject*) _Py_GetNone(void);
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030D0000
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# define Py_None _Py_GetNone()
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#else
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# define Py_None (&_Py_NoneStruct)
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#endif
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// Test if an object is the None singleton, the same as "x is None" in Python.
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PyAPI_FUNC(int) Py_IsNone(PyObject *x);
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not implemented for a given type combination.
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*/
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PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
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#define Py_NotImplemented (&_Py_NotImplementedStruct)
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PyAPI_FUNC(PyObject*) _Py_GetNotImplemented(void);
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030D0000
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# define Py_NotImplemented _Py_GetNotImplemented()
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#else
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# define Py_NotImplemented (&_Py_NotImplementedStruct)
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#endif
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/* Macro for returning Py_NotImplemented from a function */
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#define Py_RETURN_NOTIMPLEMENTED return Py_NotImplemented

‎Include/sliceobject.h‎

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@@ -7,8 +7,13 @@ extern "C" {
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/* The unique ellipsis object "..." */
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PyAPI_DATA(PyObject) _Py_EllipsisObject; /* Don't use this directly */
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PyAPI_FUNC(PyObject*) _Py_GetEllipsis(void);
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#define Py_Ellipsis (&_Py_EllipsisObject)
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#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030D0000
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# define Py_Ellipsis _Py_GetEllipsis()
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#else
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# define Py_Ellipsis (&_Py_EllipsisObject)
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#endif
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/* Slice object interface */
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‎Misc/NEWS.d/next/C API/2024-03-11-09-24-35.gh-issue-115754.zLdv82.rst‎

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In the limited C API version 3.13, getting ``Py_None``, ``Py_False``,
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``Py_True``, ``Py_Ellipsis`` and ``Py_NotImplemented`` singletons is now
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implemented as function calls at the stable ABI level to hide implementation
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details. Getting these constants still return borrowed references. Patch by
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Victor Stinner.

‎Misc/stable_abi.toml‎

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@@ -2496,3 +2496,13 @@
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[typedef.PyCFunctionFastWithKeywords]
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added = '3.13'
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# "abi-only" since 3.10. (Same story as PyCFunctionFast.)
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[typedef._Py_GetNone]
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added = '3.13'
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[typedef._Py_GetFalse]
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added = '3.13'
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[typedef._Py_GetTrue]
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added = '3.13'
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[typedef._Py_GetEllipsis]
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added = '3.13'
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[typedef._Py_GetNotImplemented]
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added = '3.13'

‎Objects/longobject.c‎

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@@ -6592,16 +6592,23 @@ _PyLong_FiniTypes(PyInterpreterState *interp)
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_PyStructSequence_FiniBuiltin(interp, &Int_InfoType);
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}
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#undef PyUnstable_Long_IsCompact
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// -- Stable ABI ------------------------------------------------------------
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#undef PyUnstable_Long_IsCompact
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int
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PyUnstable_Long_IsCompact(const PyLongObject* op) {
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return _PyLong_IsCompact(op);
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}
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#undef PyUnstable_Long_CompactValue
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Py_ssize_t
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PyUnstable_Long_CompactValue(const PyLongObject* op) {
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return _PyLong_CompactValue(op);
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}
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PyObject* _Py_GetFalse(void)
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{ return _PyObject_CAST(&_Py_FalseStruct); }
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PyObject* _Py_GetTrue(void)
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{ return _PyObject_CAST(&_Py_TrueStruct); }

‎Objects/object.c‎

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@@ -2920,6 +2920,8 @@ PyObject_GET_WEAKREFS_LISTPTR(PyObject *op)
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}
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// -- Stable ABI ------------------------------------------------------------
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#undef Py_NewRef
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#undef Py_XNewRef
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@@ -2970,3 +2972,9 @@ _Py_SetRefcnt(PyObject *ob, Py_ssize_t refcnt)
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{
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Py_SET_REFCNT(ob, refcnt);
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}
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PyObject* _Py_GetNone(void)
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{ return &_Py_NoneStruct; }
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PyObject* _Py_GetNotImplemented(void)
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{ return &_Py_NotImplementedStruct; }

‎Objects/sliceobject.c‎

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@@ -721,3 +721,9 @@ PyTypeObject PySlice_Type = {
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0, /* tp_alloc */
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slice_new, /* tp_new */
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};
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// -- Stable ABI ------------------------------------------------------------
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PyObject* _Py_GetEllipsis(void)
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{ return &_Py_EllipsisObject; }

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