Issue #24254: Drop cls.__definition_order__.

Doc/library/types.rst

@@ -53,19 +53,13 @@ Dynamic Type Creation
    in *kwds* argument with any ``'metaclass'`` entry removed. If no *kwds*
    argument is passed in, this will be an empty dict.
 
-   .. impl-detail::
-
-      CPython uses :class:`collections.OrderedDict` for the default
-      namespace.
-
    .. versionadded:: 3.3
 
    .. versionchanged:: 3.6
 
       The default value for the ``namespace`` element of the returned
-      tuple has changed from :func:`dict`.  Now an insertion-order-
-      preserving mapping is used when the metaclass does not have a
-      ``__prepare__`` method,
+      tuple has changed.  Now an insertion-order-preserving mapping is
+      used when the metaclass does not have a ``__prepare__`` method,
 
 .. seealso::
 

Doc/reference/compound_stmts.rst

@@ -634,15 +634,9 @@ dictionary.  The class name is bound to this class object in the original local
 namespace.
 
 The order in which attributes are defined in the class body is preserved
-in the ``__definition_order__`` attribute on the new class.  If that order
-is not known then the attribute is set to :const:`None`.  The class body
-may include a ``__definition_order__`` attribute.  In that case it is used
-directly.  The value must be a tuple of identifiers or ``None``, otherwise
-:exc:`TypeError` will be raised when the class statement is executed.
-
-.. versionchanged:: 3.6
-
-   Add ``__definition_order__`` to classes.
+in the new class's ``__dict__``.  Note that this is reliable only right
+after the class is created and only for classes that were defined using
+the definition syntax.
 
 Class creation can be customized heavily using :ref:`metaclasses <metaclasses>`.
 

Doc/reference/datamodel.rst

@@ -1752,13 +1752,6 @@ additional keyword arguments, if any, come from the class definition).
 If the metaclass has no ``__prepare__`` attribute, then the class namespace
 is initialised as an empty ordered mapping.
 
-.. impl-detail::
-
-   In CPython the default is :class:`collections.OrderedDict`.
-
-.. versionchanged:: 3.6
-   Defaults to :class:`collections.OrderedDict` instead of :func:`dict`.
-
 .. seealso::
 
    :pep:`3115` - Metaclasses in Python 3000

Include/object.h

@@ -421,8 +421,6 @@ typedef struct _typeobject {
 
     destructor tp_finalize;
 
-    PyObject *tp_deforder;
-
 #ifdef COUNT_ALLOCS
     /* these must be last and never explicitly initialized */
     Py_ssize_t tp_allocs;

Include/odictobject.h

@@ -28,10 +28,6 @@ PyAPI_FUNC(PyObject *) PyODict_New(void);
 PyAPI_FUNC(int) PyODict_SetItem(PyObject *od, PyObject *key, PyObject *item);
 PyAPI_FUNC(int) PyODict_DelItem(PyObject *od, PyObject *key);
 
-#ifndef Py_LIMITED_API
-PyAPI_FUNC(PyObject *) _PyODict_KeysAsTuple(PyObject *od);
-#endif
-
 /* wrappers around PyDict* functions */
 #define PyODict_GetItem(od, key) PyDict_GetItem((PyObject *)od, key)
 #define PyODict_GetItemWithError(od, key) \

Lib/test/test_builtin.py

@@ -16,10 +16,8 @@ import traceback
 import types
 import unittest
 import warnings
-from collections import OrderedDict
 from operator import neg
-from test.support import (TESTFN, unlink,  run_unittest, check_warnings,
-                          cpython_only)
+from test.support import TESTFN, unlink,  run_unittest, check_warnings
 from test.support.script_helper import assert_python_ok
 try:
     import pty, signal
@@ -1780,194 +1778,6 @@ class TestType(unittest.TestCase):
             A.__doc__ = doc
             self.assertEqual(A.__doc__, doc)
 
-    def test_type_definition_order_nonempty(self):
-        class Spam:
-            b = 1
-            c = 3
-            a = 2
-            d = 4
-            eggs = 2
-            e = 5
-            b = 42
-
-        self.assertEqual(Spam.__definition_order__,
-                         ('__module__', '__qualname__',
-                          'b', 'c', 'a', 'd', 'eggs', 'e'))
-
-    def test_type_definition_order_empty(self):
-        class Empty:
-            pass
-
-        self.assertEqual(Empty.__definition_order__,
-                         ('__module__', '__qualname__'))
-
-    def test_type_definition_order_on_instance(self):
-        class Spam:
-            a = 2
-            b = 1
-            c = 3
-        with self.assertRaises(AttributeError):
-            Spam().__definition_order__
-
-    def test_type_definition_order_set_to_None(self):
-        class Spam:
-            a = 2
-            b = 1
-            c = 3
-        Spam.__definition_order__ = None
-        self.assertEqual(Spam.__definition_order__, None)
-
-    def test_type_definition_order_set_to_tuple(self):
-        class Spam:
-            a = 2
-            b = 1
-            c = 3
-        Spam.__definition_order__ = ('x', 'y', 'z')
-        self.assertEqual(Spam.__definition_order__, ('x', 'y', 'z'))
-
-    def test_type_definition_order_deleted(self):
-        class Spam:
-            a = 2
-            b = 1
-            c = 3
-        del Spam.__definition_order__
-        self.assertEqual(Spam.__definition_order__, None)
-
-    def test_type_definition_order_set_to_bad_type(self):
-        class Spam:
-            a = 2
-            b = 1
-            c = 3
-        Spam.__definition_order__ = 42
-        self.assertEqual(Spam.__definition_order__, 42)
-
-    def test_type_definition_order_builtins(self):
-        self.assertEqual(object.__definition_order__, None)
-        self.assertEqual(type.__definition_order__, None)
-        self.assertEqual(dict.__definition_order__, None)
-        self.assertEqual(type(None).__definition_order__, None)
-
-    def test_type_definition_order_dunder_names_included(self):
-        class Dunder:
-            VAR = 3
-            def __init__(self):
-                pass
-
-        self.assertEqual(Dunder.__definition_order__,
-                         ('__module__', '__qualname__',
-                          'VAR', '__init__'))
-
-    def test_type_definition_order_only_dunder_names(self):
-        class DunderOnly:
-            __xyz__ = None
-            def __init__(self):
-                pass
-
-        self.assertEqual(DunderOnly.__definition_order__,
-                         ('__module__', '__qualname__',
-                          '__xyz__', '__init__'))
-
-    def test_type_definition_order_underscore_names(self):
-        class HalfDunder:
-            __whether_to_be = True
-            or_not_to_be__ = False
-
-        self.assertEqual(HalfDunder.__definition_order__,
-                         ('__module__', '__qualname__',
-                          '_HalfDunder__whether_to_be', 'or_not_to_be__'))
-
-    def test_type_definition_order_with_slots(self):
-        class Slots:
-            __slots__ = ('x', 'y')
-            a = 1
-            b = 2
-
-        self.assertEqual(Slots.__definition_order__,
-                         ('__module__', '__qualname__',
-                          '__slots__', 'a', 'b'))
-
-    def test_type_definition_order_overwritten_None(self):
-        class OverwrittenNone:
-            __definition_order__ = None
-            a = 1
-            b = 2
-            c = 3
-
-        self.assertEqual(OverwrittenNone.__definition_order__, None)
-
-    def test_type_definition_order_overwritten_tuple(self):
-        class OverwrittenTuple:
-            __definition_order__ = ('x', 'y', 'z')
-            a = 1
-            b = 2
-            c = 3
-
-        self.assertEqual(OverwrittenTuple.__definition_order__,
-                         ('x', 'y', 'z'))
-
-    def test_type_definition_order_overwritten_bad_item(self):
-        with self.assertRaises(TypeError):
-            class PoorlyOverwritten:
-                __definition_order__ = ('a', 2, 'c')
-                a = 1
-                b = 2
-                c = 3
-
-    def test_type_definition_order_overwritten_bad_type(self):
-        with self.assertRaises(TypeError):
-            class PoorlyOverwritten:
-                __definition_order__ = ['a', 2, 'c']
-                a = 1
-                b = 2
-                c = 3
-
-    def test_type_definition_order_metaclass(self):
-        class Meta(type):
-            SPAM = 42
-
-            def __init__(self, *args, **kwargs):
-                super().__init__(*args, **kwargs)
-
-        self.assertEqual(Meta.__definition_order__,
-                         ('__module__', '__qualname__',
-                          'SPAM', '__init__'))
-
-    def test_type_definition_order_OrderedDict(self):
-        class Meta(type):
-            def __prepare__(self, *args, **kwargs):
-                return OrderedDict()
-
-        class WithODict(metaclass=Meta):
-            x='y'
-
-        self.assertEqual(WithODict.__definition_order__,
-                         ('__module__', '__qualname__', 'x'))
-
-        class Meta(type):
-            def __prepare__(self, *args, **kwargs):
-                class ODictSub(OrderedDict):
-                    pass
-                return ODictSub()
-
-        class WithODictSub(metaclass=Meta):
-            x='y'
-
-        self.assertEqual(WithODictSub.__definition_order__,
-                         ('__module__', '__qualname__', 'x'))
-
-    @cpython_only
-    def test_type_definition_order_cpython(self):
-        # some implementations will have an ordered-by-default dict.
-
-        class Meta(type):
-            def __prepare__(self, *args, **kwargs):
-                return {}
-
-        class NotOrdered(metaclass=Meta):
-            x='y'
-
-        self.assertEqual(NotOrdered.__definition_order__, None)
-
     def test_bad_args(self):
         with self.assertRaises(TypeError):
             type()

Lib/test/test_metaclass.py

@@ -180,7 +180,7 @@ Use a metaclass that doesn't derive from type.
     meta: C ()
     ns: [('__module__', 'test.test_metaclass'), ('__qualname__', 'C'), ('a', 42), ('b', 24)]
     kw: []
-    >>> type(C) is types._DefaultClassNamespaceType
+    >>> type(C) is dict
     True
     >>> print(sorted(C.items()))
     [('__module__', 'test.test_metaclass'), ('__qualname__', 'C'), ('a', 42), ('b', 24)]
@@ -211,11 +211,8 @@ And again, with a __prepare__ attribute.
 
 The default metaclass must define a __prepare__() method.
 
-    >>> ns = type.__prepare__()
-    >>> type(ns) is types._DefaultClassNamespaceType
-    True
-    >>> list(ns) == []
-    True
+    >>> type.__prepare__()
+    {}
     >>>
 
 Make sure it works with subclassing.
@@ -251,9 +248,7 @@ Test failures in looking up the __prepare__ method work.
 
 """
 
-from collections import OrderedDict
 import sys
-import types
 
 # Trace function introduces __locals__ which causes various tests to fail.
 if hasattr(sys, 'gettrace') and sys.gettrace():

Lib/test/test_pydoc.py

@@ -427,7 +427,6 @@ class PydocDocTest(unittest.TestCase):
         expected_html = expected_html_pattern % (
                         (mod_url, mod_file, doc_loc) +
                         expected_html_data_docstrings)
-        self.maxDiff = None
         self.assertEqual(result, expected_html)
 
     @unittest.skipIf(sys.flags.optimize >= 2,
@@ -474,18 +473,13 @@ class PydocDocTest(unittest.TestCase):
     def test_non_str_name(self):
         # issue14638
         # Treat illegal (non-str) name like no name
-        # Definition order is set to None so it looks the same in both
-        # cases.
         class A:
-            __definition_order__ = None
             __name__ = 42
         class B:
             pass
         adoc = pydoc.render_doc(A())
         bdoc = pydoc.render_doc(B())
-        self.maxDiff = None
-        expected = adoc.replace("A", "B")
-        self.assertEqual(bdoc, expected)
+        self.assertEqual(adoc.replace("A", "B"), bdoc)
 
     def test_not_here(self):
         missing_module = "test.i_am_not_here"

Lib/test/test_sys.py

@@ -1085,7 +1085,7 @@ class SizeofTest(unittest.TestCase):
         check((1,2,3), vsize('') + 3*self.P)
         # type
         # static type: PyTypeObject
-        fmt = 'P2n15Pl4Pn9Pn11PIPP'
+        fmt = 'P2n15Pl4Pn9Pn11PIP'
         if hasattr(sys, 'getcounts'):
             fmt += '3n2P'
         s = vsize(fmt)

Lib/test/test_types.py

@@ -825,28 +825,6 @@ class ClassCreationTests(unittest.TestCase):
         self.assertEqual(C.y, 1)
         self.assertEqual(C.z, 2)
 
-    def test_new_class_deforder(self):
-        C = types.new_class("C")
-        self.assertEqual(C.__definition_order__, tuple())
-
-        Meta = self.Meta
-        def func(ns):
-            ns["x"] = 0
-        D = types.new_class("D", (), {"metaclass": Meta, "z": 2}, func)
-        self.assertEqual(D.__definition_order__, ('y', 'z', 'x'))
-
-        def func(ns):
-            ns["__definition_order__"] = None
-            ns["x"] = 0
-        D = types.new_class("D", (), {"metaclass": Meta, "z": 2}, func)
-        self.assertEqual(D.__definition_order__, None)
-
-        def func(ns):
-            ns["__definition_order__"] = ('a', 'b', 'c')
-            ns["x"] = 0
-        D = types.new_class("D", (), {"metaclass": Meta, "z": 2}, func)
-        self.assertEqual(D.__definition_order__, ('a', 'b', 'c'))
-
     # Many of the following tests are derived from test_descr.py
     def test_prepare_class(self):
         # Basic test of metaclass derivation

Lib/types.py

@@ -25,11 +25,8 @@ CoroutineType = type(_c)
 _c.close()  # Prevent ResourceWarning
 
 class _C:
-    _nsType = type(locals())
     def _m(self): pass
 MethodType = type(_C()._m)
-# In CPython, this should end up as OrderedDict.
-_DefaultClassNamespaceType = _C._nsType
 
 BuiltinFunctionType = type(len)
 BuiltinMethodType = type([].append)     # Same as BuiltinFunctionType
@@ -88,7 +85,7 @@ def prepare_class(name, bases=(), kwds=None):
     if hasattr(meta, '__prepare__'):
         ns = meta.__prepare__(name, bases, **kwds)
     else:
-        ns = _DefaultClassNamespaceType()
+        ns = {}
     return meta, ns, kwds
 
 def _calculate_meta(meta, bases):

Lib/typing.py

@@ -1301,7 +1301,6 @@ class _ProtocolMeta(GenericMeta):
                     if (not attr.startswith('_abc_') and
                             attr != '__abstractmethods__' and
                             attr != '_is_protocol' and
-                            attr != '__definition_order__' and
                             attr != '__dict__' and
                             attr != '__args__' and
                             attr != '__slots__' and

Objects/odictobject.c

@@ -1765,21 +1765,6 @@ PyODict_DelItem(PyObject *od, PyObject *key)
     return _PyDict_DelItem_KnownHash(od, key, hash);
 }
 
-PyObject *
-_PyODict_KeysAsTuple(PyObject *od) {
-    Py_ssize_t i = 0;
-    _ODictNode *node;
-    PyObject *keys = PyTuple_New(PyODict_Size(od));
-    if (keys == NULL)
-        return NULL;
-    _odict_FOREACH((PyODictObject *)od, node) {
-        Py_INCREF(_odictnode_KEY(node));
-        PyTuple_SET_ITEM(keys, i, _odictnode_KEY(node));
-        i++;
-    }
-    return keys;
-}
-
 
 /* -------------------------------------------
  * The OrderedDict views (keys/values/items)

Objects/typeobject.c

@@ -48,7 +48,6 @@ static size_t method_cache_collisions = 0;
 _Py_IDENTIFIER(__abstractmethods__);
 _Py_IDENTIFIER(__class__);
 _Py_IDENTIFIER(__delitem__);
-_Py_IDENTIFIER(__definition_order__);
 _Py_IDENTIFIER(__dict__);
 _Py_IDENTIFIER(__doc__);
 _Py_IDENTIFIER(__getattribute__);
@@ -489,23 +488,6 @@ type_set_module(PyTypeObject *type, PyObject *value, void *context)
     return _PyDict_SetItemId(type->tp_dict, &PyId___module__, value);
 }
 
-static PyObject *
-type_deforder(PyTypeObject *type, void *context)
-{
-    if (type->tp_deforder == NULL)
-        Py_RETURN_NONE;
-    Py_INCREF(type->tp_deforder);
-    return type->tp_deforder;
-}
-
-static int
-type_set_deforder(PyTypeObject *type, PyObject *value, void *context)
-{
-    Py_XINCREF(value);
-    Py_XSETREF(type->tp_deforder, value);
-    return 0;
-}
-
 static PyObject *
 type_abstractmethods(PyTypeObject *type, void *context)
 {
@@ -852,8 +834,6 @@ static PyGetSetDef type_getsets[] = {
     {"__qualname__", (getter)type_qualname, (setter)type_set_qualname, NULL},
     {"__bases__", (getter)type_get_bases, (setter)type_set_bases, NULL},
     {"__module__", (getter)type_module, (setter)type_set_module, NULL},
-    {"__definition_order__", (getter)type_deforder,
-     (setter)type_set_deforder, NULL},
     {"__abstractmethods__", (getter)type_abstractmethods,
      (setter)type_set_abstractmethods, NULL},
     {"__dict__",  (getter)type_dict,  NULL, NULL},
@@ -2371,7 +2351,6 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
         goto error;
     }
 
-    /* Copy the definition namespace into a new dict. */
     dict = PyDict_Copy(orig_dict);
     if (dict == NULL)
         goto error;
@@ -2580,48 +2559,6 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
     if (qualname != NULL && PyDict_DelItem(dict, PyId___qualname__.object) < 0)
         goto error;
 
-    /* Set tp_deforder to the extracted definition order, if any. */
-    type->tp_deforder = _PyDict_GetItemId(dict, &PyId___definition_order__);
-    if (type->tp_deforder != NULL) {
-        Py_INCREF(type->tp_deforder);
-
-        // Due to subclass lookup, __definition_order__ can't be in __dict__.
-        if (_PyDict_DelItemId(dict, &PyId___definition_order__) != 0) {
-            goto error;
-        }
-
-        if (type->tp_deforder != Py_None) {
-            Py_ssize_t numnames;
-
-            if (!PyTuple_Check(type->tp_deforder)) {
-                PyErr_SetString(PyExc_TypeError,
-                                "__definition_order__ must be a tuple or None");
-                goto error;
-            }
-
-            // Make sure they are identifers.
-            numnames = PyTuple_Size(type->tp_deforder);
-            for (i = 0; i < numnames; i++) {
-                PyObject *name = PyTuple_GET_ITEM(type->tp_deforder, i);
-                if (name == NULL) {
-                    goto error;
-                }
-                if (!PyUnicode_Check(name) || !PyUnicode_IsIdentifier(name)) {
-                    PyErr_Format(PyExc_TypeError,
-                                 "__definition_order__ must "
-                                 "contain only identifiers, got '%s'",
-                                 name);
-                    goto error;
-                }
-            }
-        }
-    }
-    else if (PyODict_Check(orig_dict)) {
-        type->tp_deforder = _PyODict_KeysAsTuple(orig_dict);
-        if (type->tp_deforder == NULL)
-            goto error;
-    }
-
     /* Set tp_doc to a copy of dict['__doc__'], if the latter is there
        and is a string.  The __doc__ accessor will first look for tp_doc;
        if that fails, it will still look into __dict__.
@@ -3136,7 +3073,6 @@ type_dealloc(PyTypeObject *type)
     Py_XDECREF(type->tp_mro);
     Py_XDECREF(type->tp_cache);
     Py_XDECREF(type->tp_subclasses);
-    Py_XDECREF(type->tp_deforder);
     /* A type's tp_doc is heap allocated, unlike the tp_doc slots
      * of most other objects.  It's okay to cast it to char *.
      */
@@ -3179,7 +3115,7 @@ type_subclasses(PyTypeObject *type, PyObject *args_ignored)
 static PyObject *
 type_prepare(PyObject *self, PyObject *args, PyObject *kwds)
 {
-    return PyODict_New();
+    return PyDict_New();
 }
 
 /*

Python/bltinmodule.c

@@ -147,7 +147,7 @@ builtin___build_class__(PyObject *self, PyObject *args, PyObject *kwds)
     if (prep == NULL) {
         if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
             PyErr_Clear();
-            ns = PyODict_New();
+            ns = PyDict_New();
         }
         else {
             Py_DECREF(meta);