@@ -19,12 +19,12 @@ Sentinel objects
 
    .. versionadded:: 3.15
 
-.. c:function:: PyObject* PySentinel_New(const char *name, const char *module_name)
+.. c:function:: PyObject* PySentinel_New(const char *name, const char *module_name, const char *repr)
 
    Return a new :class:`sentinel` object with :attr:`~sentinel.__name__` set to
    *name* and :attr:`~sentinel.__module__` set to *module_name*.
    *name* must not be ``NULL``. If *module_name* is ``NULL``, :attr:`~sentinel.__module__`
-   is set to ``None``.
+   is set to ``None``. If *repr* is ``NULL``, ``repr()`` returns :attr:`~sentinel.__name__`.
    Return ``NULL`` with an exception set on failure.
 
    For pickling to work, *module_name* must be the name of an importable
 
@@ -2040,6 +2040,7 @@ PySeqIter_New:PyObject*:seq:0:
 PySentinel_New:PyObject*::+1:
 PySentinel_New:const char*:name::
 PySentinel_New:const char*:module_name::
+PySentinel_New:const char*:repr::
 
 PySequence_Check:int:::
 PySequence_Check:PyObject*:o:0:
 
@@ -1827,15 +1827,21 @@ are always available.  They are listed here in alphabetical order.
       :func:`setattr`.
 
 
-.. class:: sentinel(name, /)
+.. class:: sentinel(name, /, *, repr=None)
 
    Return a new unique sentinel object.  *name* must be a :class:`str`, and is
-   used as the returned object's representation::
+   used by default as the returned object's representation::
 
       >>> MISSING = sentinel("MISSING")
       >>> MISSING
       MISSING
 
+   The optional *repr* argument can be used to specify a different representation::
+
+      >>> MISSING = sentinel("MISSING", repr="<MISSING>")
+      >>> MISSING
+      <MISSING>
+
    Sentinel objects are truthy and compare equal only to themselves.  They are
    intended to be compared with the :keyword:`is` operator.
 
@@ -1879,7 +1885,7 @@ are always available.  They are listed here in alphabetical order.
 
    .. attribute:: __module__
 
-      The name of the module where the sentinel was created.
+      The name of the module where the sentinel was created. This attribute is writable.
 
    .. versionadded:: 3.15
 
 
@@ -13,7 +13,8 @@ PyAPI_DATA(PyTypeObject) PySentinel_Type;
 
 PyAPI_FUNC(PyObject *) PySentinel_New(
     const char *name,
-    const char *module_name);
+    const char *module_name,
+    const char *repr);
 
 #ifdef __cplusplus
 }
 
@@ -754,6 +754,7 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(repeat)
         STRUCT_FOR_ID(repl)
         STRUCT_FOR_ID(replace)
+        STRUCT_FOR_ID(repr)
         STRUCT_FOR_ID(reqrefs)
         STRUCT_FOR_ID(require_ready)
         STRUCT_FOR_ID(reserved)
 
@@ -1956,16 +1956,33 @@ def test_sentinel(self):
         with self.assertRaises(TypeError):
             class SubSentinel(sentinel):
                 pass
+
+    def test_sentinel_attributes(self):
+        missing = sentinel("MISSING")
         with self.assertRaises(TypeError):
             sentinel.attribute = "value"
         with self.assertRaises(AttributeError):
-            missing.__name__ = "CHANGED"
+            missing.attribute = "value"
         with self.assertRaises(AttributeError):
-            missing.__module__ = "changed"
+            missing.__name__ = "CHANGED"
+        missing.__module__ = "changed"
+        self.assertEqual(missing.__module__, "changed")
         with self.assertRaises(AttributeError):
             del missing.__name__
+        del missing.__module__
         with self.assertRaises(AttributeError):
-            del missing.__module__
+            missing.__module__
+
+    def test_sentinel_repr(self):
+        with_repr = sentinel("WITH_REPR", repr="custom")
+        without_repr = sentinel("WITHOUT_REPR", repr=None)
+        self.assertEqual(repr(with_repr), "custom")
+        self.assertEqual(repr(without_repr), "WITHOUT_REPR")
+        self.assertEqual(str(with_repr), "custom")
+        self.assertEqual(str(without_repr), "WITHOUT_REPR")
+
+        with self.assertRaisesRegex(TypeError, "repr.*str or None"):
+            sentinel("BAD_REPR", repr=42)
 
     def test_sentinel_pickle(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
 
@@ -80,6 +80,12 @@ def test_pysentinel_new(self):
         self.assertEqual(no_module.__name__, "NO_MODULE")
         self.assertIs(no_module.__module__, None)
 
+        with_repr = _testcapi.pysentinel_new("WITH_REPR", __name__, "custom repr")
+        self.assertIs(type(with_repr), sentinel)
+        self.assertEqual(with_repr.__name__, "WITH_REPR")
+        self.assertEqual(with_repr.__module__, __name__)
+        self.assertEqual(repr(with_repr), "custom repr")
+
         globals()["CAPI_SENTINEL"] = marker
         self.addCleanup(globals().pop, "CAPI_SENTINEL", None)
         self.assertIs(pickle.loads(pickle.dumps(marker)), marker)
Original file line number	Diff line number	Diff line change
@@ -13,7 +13,8 @@ PyAPI_DATA(PyTypeObject) PySentinel_Type;
13	13
14	14	PyAPI_FUNC(PyObject *) PySentinel_New(
15	15	const char *name,
16		- const char *module_name);
	16	+ const char *module_name,
	17	+ const char *repr);
17	18
18	19	#ifdef __cplusplus
19	20	}