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Issue #24254: Preserve class attribute definition order.

This commit is contained in:
Eric Snow 2016-09-05 14:50:11 -07:00
parent 4565986138
commit 92a6c170e6
18 changed files with 568 additions and 189 deletions
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367
Doc/library/inspect.rst
View File

@ -34,185 +34,190 @@ provided as convenient choices for the second argument to :func:`getmembers`.
They also help you determine when you can expect to find the following special
attributes:
+-----------+-----------------+---------------------------+
| Type | Attribute | Description |
+===========+=================+===========================+
| module | __doc__ | documentation string |
+-----------+-----------------+---------------------------+
| | __file__ | filename (missing for |
| | | built-in modules) |
+-----------+-----------------+---------------------------+
| class | __doc__ | documentation string |
+-----------+-----------------+---------------------------+
| | __name__ | name with which this |
| | | class was defined |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | __module__ | name of module in which |
| | | this class was defined |
+-----------+-----------------+---------------------------+
| method | __doc__ | documentation string |
+-----------+-----------------+---------------------------+
| | __name__ | name with which this |
| | | method was defined |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | __func__ | function object |
| | | containing implementation |
| | | of method |
+-----------+-----------------+---------------------------+
| | __self__ | instance to which this |
| | | method is bound, or |
| | | ``None`` |
+-----------+-----------------+---------------------------+
| function | __doc__ | documentation string |
+-----------+-----------------+---------------------------+
| | __name__ | name with which this |
| | | function was defined |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | __code__ | code object containing |
| | | compiled function |
| | | :term:`bytecode` |
+-----------+-----------------+---------------------------+
| | __defaults__ | tuple of any default |
| | | values for positional or |
| | | keyword parameters |
+-----------+-----------------+---------------------------+
| | __kwdefaults__ | mapping of any default |
| | | values for keyword-only |
| | | parameters |
+-----------+-----------------+---------------------------+
| | __globals__ | global namespace in which |
| | | this function was defined |
+-----------+-----------------+---------------------------+
| | __annotations__ | mapping of parameters |
| | | names to annotations; |
| | | ``"return"`` key is |
| | | reserved for return |
| | | annotations. |
+-----------+-----------------+---------------------------+
| traceback | tb_frame | frame object at this |
| | | level |
+-----------+-----------------+---------------------------+
| | tb_lasti | index of last attempted |
| | | instruction in bytecode |
+-----------+-----------------+---------------------------+
| | tb_lineno | current line number in |
| | | Python source code |
+-----------+-----------------+---------------------------+
| | tb_next | next inner traceback |
| | | object (called by this |
| | | level) |
+-----------+-----------------+---------------------------+
| frame | f_back | next outer frame object |
| | | (this frame's caller) |
+-----------+-----------------+---------------------------+
| | f_builtins | builtins namespace seen |
| | | by this frame |
+-----------+-----------------+---------------------------+
| | f_code | code object being |
| | | executed in this frame |
+-----------+-----------------+---------------------------+
| | f_globals | global namespace seen by |
| | | this frame |
+-----------+-----------------+---------------------------+
| | f_lasti | index of last attempted |
| | | instruction in bytecode |
+-----------+-----------------+---------------------------+
| | f_lineno | current line number in |
| | | Python source code |
+-----------+-----------------+---------------------------+
| | f_locals | local namespace seen by |
| | | this frame |
+-----------+-----------------+---------------------------+
| | f_restricted | 0 or 1 if frame is in |
| | | restricted execution mode |
+-----------+-----------------+---------------------------+
| | f_trace | tracing function for this |
| | | frame, or ``None`` |
+-----------+-----------------+---------------------------+
| code | co_argcount | number of arguments (not |
| | | including \* or \*\* |
| | | args) |
+-----------+-----------------+---------------------------+
| | co_code | string of raw compiled |
| | | bytecode |
+-----------+-----------------+---------------------------+
| | co_consts | tuple of constants used |
| | | in the bytecode |
+-----------+-----------------+---------------------------+
| | co_filename | name of file in which |
| | | this code object was |
| | | created |
+-----------+-----------------+---------------------------+
| | co_firstlineno | number of first line in |
| | | Python source code |
+-----------+-----------------+---------------------------+
| | co_flags | bitmap: 1=optimized ``|`` |
| | | 2=newlocals ``|`` 4=\*arg |
| | | ``|`` 8=\*\*arg |
+-----------+-----------------+---------------------------+
| | co_lnotab | encoded mapping of line |
| | | numbers to bytecode |
| | | indices |
+-----------+-----------------+---------------------------+
| | co_name | name with which this code |
| | | object was defined |
+-----------+-----------------+---------------------------+
| | co_names | tuple of names of local |
| | | variables |
+-----------+-----------------+---------------------------+
| | co_nlocals | number of local variables |
+-----------+-----------------+---------------------------+
| | co_stacksize | virtual machine stack |
| | | space required |
+-----------+-----------------+---------------------------+
| | co_varnames | tuple of names of |
| | | arguments and local |
| | | variables |
+-----------+-----------------+---------------------------+
| generator | __name__ | name |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | gi_frame | frame |
+-----------+-----------------+---------------------------+
| | gi_running | is the generator running? |
+-----------+-----------------+---------------------------+
| | gi_code | code |
+-----------+-----------------+---------------------------+
| | gi_yieldfrom | object being iterated by |
| | | ``yield from``, or |
| | | ``None`` |
+-----------+-----------------+---------------------------+
| coroutine | __name__ | name |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | cr_await | object being awaited on, |
| | | or ``None`` |
+-----------+-----------------+---------------------------+
| | cr_frame | frame |
+-----------+-----------------+---------------------------+
| | cr_running | is the coroutine running? |
+-----------+-----------------+---------------------------+
| | cr_code | code |
+-----------+-----------------+---------------------------+
| builtin | __doc__ | documentation string |
+-----------+-----------------+---------------------------+
| | __name__ | original name of this |
| | | function or method |
+-----------+-----------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+-----------------+---------------------------+
| | __self__ | instance to which a |
| | | method is bound, or |
| | | ``None`` |
+-----------+-----------------+---------------------------+
+-----------+----------------------+---------------------------+
| Type | Attribute | Description |
+===========+======================+===========================+
| module | __doc__ | documentation string |
+-----------+----------------------+---------------------------+
| | __file__ | filename (missing for |
| | | built-in modules) |
+-----------+----------------------+---------------------------+
| class | __doc__ | documentation string |
+-----------+----------------------+---------------------------+
| | __name__ | name with which this |
| | | class was defined |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | __module__ | name of module in which |
| | | this class was defined |
+-----------+----------------------+---------------------------+
| | __definition_order__ | the names of the class's |
| | | attributes, in the order |
| | | in which they were |
| | | defined (if known) |
+-----------+----------------------+---------------------------+
| method | __doc__ | documentation string |
+-----------+----------------------+---------------------------+
| | __name__ | name with which this |
| | | method was defined |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | __func__ | function object |
| | | containing implementation |
| | | of method |
+-----------+----------------------+---------------------------+
| | __self__ | instance to which this |
| | | method is bound, or |
| | | ``None`` |
+-----------+----------------------+---------------------------+
| function | __doc__ | documentation string |
+-----------+----------------------+---------------------------+
| | __name__ | name with which this |
| | | function was defined |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | __code__ | code object containing |
| | | compiled function |
| | | :term:`bytecode` |
+-----------+----------------------+---------------------------+
| | __defaults__ | tuple of any default |
| | | values for positional or |
| | | keyword parameters |
+-----------+----------------------+---------------------------+
| | __kwdefaults__ | mapping of any default |
| | | values for keyword-only |
| | | parameters |
+-----------+----------------------+---------------------------+
| | __globals__ | global namespace in which |
| | | this function was defined |
+-----------+----------------------+---------------------------+
| | __annotations__ | mapping of parameters |
| | | names to annotations; |
| | | ``"return"`` key is |
| | | reserved for return |
| | | annotations. |
+-----------+----------------------+---------------------------+
| traceback | tb_frame | frame object at this |
| | | level |
+-----------+----------------------+---------------------------+
| | tb_lasti | index of last attempted |
| | | instruction in bytecode |
+-----------+----------------------+---------------------------+
| | tb_lineno | current line number in |
| | | Python source code |
+-----------+----------------------+---------------------------+
| | tb_next | next inner traceback |
| | | object (called by this |
| | | level) |
+-----------+----------------------+---------------------------+
| frame | f_back | next outer frame object |
| | | (this frame's caller) |
+-----------+----------------------+---------------------------+
| | f_builtins | builtins namespace seen |
| | | by this frame |
+-----------+----------------------+---------------------------+
| | f_code | code object being |
| | | executed in this frame |
+-----------+----------------------+---------------------------+
| | f_globals | global namespace seen by |
| | | this frame |
+-----------+----------------------+---------------------------+
| | f_lasti | index of last attempted |
| | | instruction in bytecode |
+-----------+----------------------+---------------------------+
| | f_lineno | current line number in |
| | | Python source code |
+-----------+----------------------+---------------------------+
| | f_locals | local namespace seen by |
| | | this frame |
+-----------+----------------------+---------------------------+
| | f_restricted | 0 or 1 if frame is in |
| | | restricted execution mode |
+-----------+----------------------+---------------------------+
| | f_trace | tracing function for this |
| | | frame, or ``None`` |
+-----------+----------------------+---------------------------+
| code | co_argcount | number of arguments (not |
| | | including \* or \*\* |
| | | args) |
+-----------+----------------------+---------------------------+
| | co_code | string of raw compiled |
| | | bytecode |
+-----------+----------------------+---------------------------+
| | co_consts | tuple of constants used |
| | | in the bytecode |
+-----------+----------------------+---------------------------+
| | co_filename | name of file in which |
| | | this code object was |
| | | created |
+-----------+----------------------+---------------------------+
| | co_firstlineno | number of first line in |
| | | Python source code |
+-----------+----------------------+---------------------------+
| | co_flags | bitmap: 1=optimized ``|`` |
| | | 2=newlocals ``|`` 4=\*arg |
| | | ``|`` 8=\*\*arg |
+-----------+----------------------+---------------------------+
| | co_lnotab | encoded mapping of line |
| | | numbers to bytecode |
| | | indices |
+-----------+----------------------+---------------------------+
| | co_name | name with which this code |
| | | object was defined |
+-----------+----------------------+---------------------------+
| | co_names | tuple of names of local |
| | | variables |
+-----------+----------------------+---------------------------+
| | co_nlocals | number of local variables |
+-----------+----------------------+---------------------------+
| | co_stacksize | virtual machine stack |
| | | space required |
+-----------+----------------------+---------------------------+
| | co_varnames | tuple of names of |
| | | arguments and local |
| | | variables |
+-----------+----------------------+---------------------------+
| generator | __name__ | name |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | gi_frame | frame |
+-----------+----------------------+---------------------------+
| | gi_running | is the generator running? |
+-----------+----------------------+---------------------------+
| | gi_code | code |
+-----------+----------------------+---------------------------+
| | gi_yieldfrom | object being iterated by |
| | | ``yield from``, or |
| | | ``None`` |
+-----------+----------------------+---------------------------+
| coroutine | __name__ | name |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | cr_await | object being awaited on, |
| | | or ``None`` |
+-----------+----------------------+---------------------------+
| | cr_frame | frame |
+-----------+----------------------+---------------------------+
| | cr_running | is the coroutine running? |
+-----------+----------------------+---------------------------+
| | cr_code | code |
+-----------+----------------------+---------------------------+
| builtin | __doc__ | documentation string |
+-----------+----------------------+---------------------------+
| | __name__ | original name of this |
| | | function or method |
+-----------+----------------------+---------------------------+
| | __qualname__ | qualified name |
+-----------+----------------------+---------------------------+
| | __self__ | instance to which a |
| | | method is bound, or |
| | | ``None`` |
+-----------+----------------------+---------------------------+
.. versionchanged:: 3.5
@ -221,6 +226,10 @@ attributes:
The ``__name__`` attribute of generators is now set from the function
name, instead of the code name, and it can now be modified.
.. versionchanged:: 3.6
Add ``__definition_order__`` to classes.
.. function:: getmembers(object[, predicate])

12
Doc/library/types.rst
View File

@ -53,8 +53,20 @@ 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,
.. seealso::
:ref:`metaclasses`

11
Doc/reference/compound_stmts.rst
View File

@ -632,6 +632,17 @@ list for the base classes and the saved local namespace for the attribute
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.
Class creation can be customized heavily using :ref:`metaclasses <metaclasses>`.
Classes can also be decorated: just like when decorating functions, ::

9
Doc/reference/datamodel.rst
View File

@ -1750,7 +1750,14 @@ as ``namespace = metaclass.__prepare__(name, bases, **kwds)`` (where the
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 :func:`dict` instance.
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::

26
Doc/whatsnew/3.6.rst
View File

@ -92,6 +92,7 @@ Windows improvements:
:pep:`4XX` - Python Virtual Environments
PEP written by Carl Meyer
.. XXX PEP 520: :ref:`Preserving Class Attribute Definition Order<whatsnew-deforder>`
New Features
============
@ -271,6 +272,31 @@ Example of fatal error on buffer overflow using
(Contributed by Victor Stinner in :issue:`26516` and :issue:`26564`.)
.. _whatsnew-deforder:
PEP 520: Preserving Class Attribute Definition Order
----------------------------------------------------
Attributes in a class definition body have a natural ordering: the same
order in which the names appear in the source. This order is now
preserved in the new class's ``__definition_order__`` attribute. It is
a tuple of the attribute names, in the order in which they appear in
the class definition body.
For types that don't have a definition (e.g. builtins), or the attribute
order could not be determined, ``__definition_order__`` is ``None``.
Also, the effective default class *execution* namespace (returned from
``type.__prepare__()``) is now an insertion-order-preserving mapping.
For CPython, it is now ``collections.OrderedDict``. Note that the
class namespace, ``cls.__dict__``, is unchanged.
.. seealso::
:pep:`520` - Preserving Class Attribute Definition Order
PEP written and implemented by Eric Snow.
Other Language Changes
======================

2
Include/object.h
View File

@ -421,6 +421,8 @@ 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;

4
Include/odictobject.h
View File

@ -28,6 +28,10 @@ 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) \

192
Lib/test/test_builtin.py
View File

@ -16,8 +16,10 @@ 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
from test.support import (TESTFN, unlink, run_unittest, check_warnings,
cpython_only)
from test.support.script_helper import assert_python_ok
try:
import pty, signal
@ -1778,6 +1780,194 @@ 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()

11
Lib/test/test_metaclass.py
View File

@ -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 dict
>>> type(C) is types._DefaultClassNamespaceType
True
>>> print(sorted(C.items()))
[('__module__', 'test.test_metaclass'), ('__qualname__', 'C'), ('a', 42), ('b', 24)]
@ -211,8 +211,11 @@ And again, with a __prepare__ attribute.
The default metaclass must define a __prepare__() method.
>>> type.__prepare__()
{}
>>> ns = type.__prepare__()
>>> type(ns) is types._DefaultClassNamespaceType
True
>>> list(ns) == []
True
>>>
Make sure it works with subclassing.
@ -248,7 +251,9 @@ 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():

8
Lib/test/test_pydoc.py
View File

@ -427,6 +427,7 @@ 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,
@ -473,13 +474,18 @@ 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.assertEqual(adoc.replace("A", "B"), bdoc)
self.maxDiff = None
expected = adoc.replace("A", "B")
self.assertEqual(bdoc, expected)
def test_not_here(self):
missing_module = "test.i_am_not_here"

2
Lib/test/test_sys.py
View File

@ -1084,7 +1084,7 @@ class SizeofTest(unittest.TestCase):
check((1,2,3), vsize('') + 3*self.P)
# type
# static type: PyTypeObject
fmt = 'P2n15Pl4Pn9Pn11PIP'
fmt = 'P2n15Pl4Pn9Pn11PIPP'
if hasattr(sys, 'getcounts'):
fmt += '3n2P'
s = vsize(fmt)

22
Lib/test/test_types.py
View File

@ -825,6 +825,28 @@ 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

5
Lib/types.py
View File

@ -25,8 +25,11 @@ 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
@ -85,7 +88,7 @@ def prepare_class(name, bases=(), kwds=None):
if hasattr(meta, '__prepare__'):
ns = meta.__prepare__(name, bases, **kwds)
else:
ns = {}
ns = _DefaultClassNamespaceType()
return meta, ns, kwds
def _calculate_meta(meta, bases):

1
Lib/typing.py
View File

@ -1301,6 +1301,7 @@ 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

2
Misc/NEWS
View File

@ -49,6 +49,8 @@ Core and Builtins
potentially have caused off-by-one-ulp results on platforms with
unreliable ldexp implementations.
- Issue #24254: Make class definition namespace ordered by default.
- Issue #27662: Fix an overflow check in ``List_New``: the original code was
checking against ``Py_SIZE_MAX`` instead of the correct upper bound of
``Py_SSIZE_T_MAX``. Patch by Xiang Zhang.

15
Objects/odictobject.c
View File

@ -1762,6 +1762,21 @@ 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)

66
Objects/typeobject.c
View File

@ -48,6 +48,7 @@ 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__);
@ -488,6 +489,23 @@ 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)
{
@ -834,6 +852,8 @@ 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},
@ -2351,6 +2371,7 @@ 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;
@ -2559,6 +2580,48 @@ 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__.
@ -3073,6 +3136,7 @@ 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 *.
*/
@ -3115,7 +3179,7 @@ type_subclasses(PyTypeObject *type, PyObject *args_ignored)
static PyObject *
type_prepare(PyObject *self, PyObject *args, PyObject *kwds)
{
return PyDict_New();
return PyODict_New();
}
/*

2
Python/bltinmodule.c
View File

@ -145,7 +145,7 @@ builtin___build_class__(PyObject *self, PyObject *args, PyObject *kwds)
if (prep == NULL) {
if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
PyErr_Clear();
ns = PyDict_New();
ns = PyODict_New();
}
else {
Py_DECREF(meta);