python · vstinner · Jun 3, 2024 · Mar 10, 2024 · Mar 10, 2024 · Mar 11, 2024
@@ -494,6 +494,17 @@ distinguished from a number.  Use :c:func:`PyErr_Occurred` to disambiguate.
    .. versionadded:: 3.13
 
 
+.. c:function:: int PyLong_GetSign(PyObject *obj, int *sign)
+
+   Retrieve the sign of integer object *obj* (``0``, ``-1`` or ``+1`` for zero,
+   negative or positive integer, respectively) in a variable *sign*.
+
+   Return ``0`` on success, else ``-1`` with an exception set.  This function
+   always succeeds if *obj* is a :c:type:`PyLongObject` or its subtype.
+
+   .. versionadded:: 3.13
+
+
 .. c:function:: int PyUnstable_Long_IsCompact(const PyLongObject* op)
 
    Return 1 if *op* is compact, 0 otherwise.

diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
@@ -2130,6 +2130,9 @@ New Features
   between native integer types and Python :class:`int` objects.
   (Contributed by Steve Dower in :gh:`111140`.)
 
+* Add :c:func:`PyLong_GetSign` function to test sign of :class:`int` objects.
+  Contributed by Sergey B Kirpichev.
+
 * Add :c:func:`PyType_GetFullyQualifiedName` function to get the type's fully
   qualified name. Equivalent to ``f"{type.__module__}.{type.__qualname__}"``,
   or ``type.__qualname__`` if ``type.__module__`` is not a string or is equal

diff --git a/Include/cpython/longobject.h b/Include/cpython/longobject.h
@@ -55,9 +55,10 @@ PyAPI_FUNC(PyObject*) PyLong_FromUnsignedNativeBytes(const void* buffer,
 PyAPI_FUNC(int) PyUnstable_Long_IsCompact(const PyLongObject* op);
 PyAPI_FUNC(Py_ssize_t) PyUnstable_Long_CompactValue(const PyLongObject* op);
 
-// _PyLong_Sign.  Return 0 if v is 0, -1 if v < 0, +1 if v > 0.
-// v must not be NULL, and must be a normalized long.
-// There are no error cases.
+/* PyLong_GetSign.  Retrieve the sign of the integer value (0, -1 or +1) in
+   a variable sign.  Return 0 on success, else -1 with an exception set. */
+PyAPI_FUNC(int) PyLong_GetSign(PyObject *v, int *sign);
+
 PyAPI_FUNC(int) _PyLong_Sign(PyObject *v);
 
 /* _PyLong_NumBits.  Return the number of bits needed to represent the

diff --git a/Lib/test/test_capi/test_long.py b/Lib/test/test_capi/test_long.py
@@ -721,6 +721,21 @@ def test_long_fromnativebytes(self):
                 self.assertEqual(expect_u, fromnativebytes(v_be, n, 4, 1),
                     f"PyLong_FromNativeBytes(buffer, {n}, <big|unsigned>)")
 
+    def test_long_sign(self):
+        # Test PyLong_GetSign()
+        sign = _testcapi.pylong_getsign
+        self.assertEqual(sign(1), 1)
+        self.assertEqual(sign(123456), 1)
+        self.assertEqual(sign(-2), -1)
+        self.assertEqual(sign(0), 0)
+        self.assertEqual(sign(True), 1)
+        self.assertEqual(sign(IntSubclass(-11)), -1)
+        self.assertEqual(sign(False), 0)
+
+        self.assertRaises(TypeError, sign, 1.0)
+        self.assertRaises(TypeError, sign, Index(123))
+        self.assertRaises(SystemError, sign, NULL)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/C API/2024-03-10-14-55-51.gh-issue-116560.x2mZaO.rst b/Misc/NEWS.d/next/C API/2024-03-10-14-55-51.gh-issue-116560.x2mZaO.rst
@@ -0,0 +1 @@
+Add :c:func:`PyLong_GetSign` function.  Patch by Sergey B Kirpichev.
diff --git a/Modules/_testcapi/long.c b/Modules/_testcapi/long.c
@@ -92,6 +92,19 @@ pylong_fromnativebytes(PyObject *module, PyObject *args)
     return res;
 }
 
+
+static PyObject *
+pylong_getsign(PyObject *module, PyObject *arg)
+{
+    NULLABLE(arg);
+    int sign;
+    if (PyLong_GetSign(arg, &sign) == -1) {
+        return NULL;
+    }
+    return PyLong_FromLong(sign);
+}
+
+
 static PyObject *
 pylong_aspid(PyObject *module, PyObject *arg)
 {
@@ -109,6 +122,7 @@ static PyMethodDef test_methods[] = {
     {"pylong_fromunicodeobject",    pylong_fromunicodeobject,   METH_VARARGS},
     {"pylong_asnativebytes",        pylong_asnativebytes,       METH_VARARGS},
     {"pylong_fromnativebytes",      pylong_fromnativebytes,     METH_VARARGS},
+    {"pylong_getsign",              pylong_getsign,             METH_O},
     {"pylong_aspid",                pylong_aspid,               METH_O},
     {NULL},
 };

diff --git a/Objects/longobject.c b/Objects/longobject.c
@@ -770,6 +770,22 @@ _PyLong_Sign(PyObject *vv)
     return _PyLong_NonCompactSign(v);
 }
 
+int
+PyLong_GetSign(PyObject *vv, int *sign)
+{
+    if (vv == NULL) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
+    if (!PyLong_Check(vv)) {
+        PyErr_Format(PyExc_TypeError, "expect int, got %T", vv);
+        return -1;
+    }
+
+    *sign = _PyLong_Sign(vv);
+    return 0;
+}
+
 static int
 bit_length_digit(digit x)
 {
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Add :c:func:`PyLong_GetSign` function. Patch by Sergey B Kirpichev.