more tweaks

Author: JelleZijlstra

Doc/library/functions.rst

@@ -1841,10 +1841,6 @@ are always available.  They are listed here in alphabetical order.
 
    Shallow and deep copies of a sentinel object return the object itself.
 
-   Sentinels importable from their defining module by name preserve their
-   identity when pickled and unpickled.  Sentinels that are not importable by
-   module and name are not picklable.
-
    Sentinels are conventionally assigned to a variable with a matching name.
    Sentinels defined in this way can be used in :term:`type hints <type hint>`::
 
@@ -1858,7 +1854,8 @@ are always available.  They are listed here in alphabetical order.
    :mod:`Pickling <pickle>` is supported for sentinel objects that are
    placed in the global scope of a module under a name matching the sentinel's
    name, and for sentinels placed in class scopes with a name matching the
-   :term:`qualified name` of the sentinel. The identity of the sentinel is preserved
+   :term:`qualified name` of the sentinel. Other sentinels, such as those
+   defined in a function scope, are not picklable. The identity of the sentinel is preserved
    after pickling::
 
       import pickle
@@ -1872,6 +1869,8 @@ are always available.  They are listed here in alphabetical order.
 
       assert pickle.loads(pickle.dumps(Cls.PICKLABLE)) is Cls.PICKLABLE
 
+   Sentinel objects have the following attributes:
+
    .. attribute:: __name__
 
       The sentinel's name.

Lib/test/test_builtin.py

@@ -1941,6 +1941,10 @@ class SubSentinel(sentinel):
             missing.__name__ = "CHANGED"
         with self.assertRaises(AttributeError):
             missing.__module__ = "changed"
+        with self.assertRaises(AttributeError):
+            del missing.__name__
+        with self.assertRaises(AttributeError):
+            del missing.__module__
 
     def test_sentinel_pickle(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
@@ -1977,10 +1981,25 @@ class Name(str):
     def test_sentinel_union(self):
         missing = sentinel("MISSING")
 
+        self.assertIsInstance(missing | int, typing.Union)
         self.assertEqual((missing | int).__args__, (missing, int))
+        self.assertIsInstance(int | missing, typing.Union)
         self.assertEqual((int | missing).__args__, (int, missing))
         self.assertIs(missing | missing, missing)
         self.assertEqual(repr(int | missing), "int | MISSING")
+        self.assertIsInstance(missing | None, typing.Union)
+        self.assertEqual((missing | None).__args__, (missing, type(None)))
+        self.assertIsInstance(None | missing, typing.Union)
+        self.assertEqual((None | missing).__args__, (type(None), missing))
+        self.assertIsInstance(missing | list[int], typing.Union)
+        self.assertEqual((missing | list[int]).__args__, (missing, list[int]))
+        self.assertIsInstance(missing | (int | str), typing.Union)
+        self.assertEqual((missing | (int | str)).__args__, (missing, int, str))
+
+        with self.assertRaises(TypeError):
+            missing | 1
+        with self.assertRaises(TypeError):
+            1 | missing
 
     def test_round(self):
         self.assertEqual(round(0.0), 0.0)

Lib/test/test_capi/test_object.py

@@ -1,5 +1,6 @@
 import enum
 import os
+import pickle
 import sys
 import textwrap
 import unittest
@@ -66,8 +67,6 @@ def test_get_constant_borrowed(self):
 class SentinelTest(unittest.TestCase):
 
     def test_pysentinel_new(self):
-        import pickle
-
         marker = _testcapi.pysentinel_new("CAPI_SENTINEL", __name__)
         self.assertIs(type(marker), sentinel)
         self.assertTrue(_testcapi.pysentinel_check(marker))

Objects/sentinelobject.c

@@ -8,7 +8,7 @@
 #include "pycore_stackref.h"      // PyStackRef_AsPyObjectBorrow()
 #include "pycore_tuple.h"         // _PyTuple_FromPair
 #include "pycore_typeobject.h"    // _Py_BaseObject_RichCompare()
-#include "pycore_unionobject.h"   // _Py_union_from_tuple()
+#include "pycore_unionobject.h"   // _Py_union_type_or()
 
 typedef struct {
     PyObject_HEAD
@@ -152,18 +152,6 @@ sentinel_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))
     return Py_NewRef(self->name);
 }
 
-static PyObject *
-sentinel_or(PyObject *self, PyObject *other)
-{
-    PyObject *args = _PyTuple_FromPair(self, other);
-    if (args == NULL) {
-        return NULL;
-    }
-    PyObject *result = _Py_union_from_tuple(args);
-    Py_DECREF(args);
-    return result;
-}
-
 static PyMethodDef sentinel_methods[] = {
     {"__copy__", sentinel_copy, METH_NOARGS, NULL},
     {"__deepcopy__", sentinel_deepcopy, METH_O, NULL},
@@ -178,7 +166,7 @@ static PyMemberDef sentinel_members[] = {
 };
 
 static PyNumberMethods sentinel_as_number = {
-    .nb_or = sentinel_or,
+    .nb_or = _Py_union_type_or,
 };
 
 PyDoc_STRVAR(sentinel_doc,