[Python-checkins] cpython: Issue #24254: Preserve class attribute definition order.
eric.snow
python-checkins at python.org
Mon Sep 5 17:53:50 EDT 2016
https://hg.python.org/cpython/rev/635fd3912d4d
changeset: 103071:635fd3912d4d
user: Eric Snow <ericsnowcurrently at gmail.com>
date: Mon Sep 05 14:50:11 2016 -0700
summary:
Issue #24254: Preserve class attribute definition order.
files:
Doc/library/inspect.rst | 367 +++++++++---------
Doc/library/types.rst | 12 +
Doc/reference/compound_stmts.rst | 11 +
Doc/reference/datamodel.rst | 9 +-
Doc/whatsnew/3.6.rst | 26 +
Include/object.h | 2 +
Include/odictobject.h | 4 +
Lib/test/test_builtin.py | 192 +++++++++-
Lib/test/test_metaclass.py | 11 +-
Lib/test/test_pydoc.py | 8 +-
Lib/test/test_sys.py | 2 +-
Lib/test/test_types.py | 22 +
Lib/types.py | 5 +-
Lib/typing.py | 1 +
Misc/NEWS | 2 +
Objects/odictobject.c | 15 +
Objects/typeobject.c | 66 +++-
Python/bltinmodule.c | 2 +-
18 files changed, 568 insertions(+), 189 deletions(-)
diff --git a/Doc/library/inspect.rst b/Doc/library/inspect.rst
--- a/Doc/library/inspect.rst
+++ b/Doc/library/inspect.rst
@@ -34,185 +34,190 @@
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 @@
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])
diff --git a/Doc/library/types.rst b/Doc/library/types.rst
--- a/Doc/library/types.rst
+++ b/Doc/library/types.rst
@@ -53,8 +53,20 @@
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`
diff --git a/Doc/reference/compound_stmts.rst b/Doc/reference/compound_stmts.rst
--- a/Doc/reference/compound_stmts.rst
+++ b/Doc/reference/compound_stmts.rst
@@ -632,6 +632,17 @@
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, ::
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1750,7 +1750,14 @@
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::
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -92,6 +92,7 @@
: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 @@
(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
======================
diff --git a/Include/object.h b/Include/object.h
--- a/Include/object.h
+++ b/Include/object.h
@@ -421,6 +421,8 @@
destructor tp_finalize;
+ PyObject *tp_deforder;
+
#ifdef COUNT_ALLOCS
/* these must be last and never explicitly initialized */
Py_ssize_t tp_allocs;
diff --git a/Include/odictobject.h b/Include/odictobject.h
--- a/Include/odictobject.h
+++ b/Include/odictobject.h
@@ -28,6 +28,10 @@
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) \
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -16,8 +16,10 @@
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 @@
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()
diff --git a/Lib/test/test_metaclass.py b/Lib/test/test_metaclass.py
--- a/Lib/test/test_metaclass.py
+++ b/Lib/test/test_metaclass.py
@@ -180,7 +180,7 @@
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 @@
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 @@
"""
+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():
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -427,6 +427,7 @@
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 @@
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"
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1084,7 +1084,7 @@
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)
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -825,6 +825,28 @@
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
diff --git a/Lib/types.py b/Lib/types.py
--- a/Lib/types.py
+++ b/Lib/types.py
@@ -25,8 +25,11 @@
_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 @@
if hasattr(meta, '__prepare__'):
ns = meta.__prepare__(name, bases, **kwds)
else:
- ns = {}
+ ns = _DefaultClassNamespaceType()
return meta, ns, kwds
def _calculate_meta(meta, bases):
diff --git a/Lib/typing.py b/Lib/typing.py
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1301,6 +1301,7 @@
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
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -49,6 +49,8 @@
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.
diff --git a/Objects/odictobject.c b/Objects/odictobject.c
--- a/Objects/odictobject.c
+++ b/Objects/odictobject.c
@@ -1762,6 +1762,21 @@
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)
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -48,6 +48,7 @@
_Py_IDENTIFIER(__abstractmethods__);
_Py_IDENTIFIER(__class__);
_Py_IDENTIFIER(__delitem__);
+_Py_IDENTIFIER(__definition_order__);
_Py_IDENTIFIER(__dict__);
_Py_IDENTIFIER(__doc__);
_Py_IDENTIFIER(__getattribute__);
@@ -489,6 +490,23 @@
}
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)
{
PyObject *mod = NULL;
@@ -834,6 +852,8 @@
{"__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 @@
goto error;
}
+ /* Copy the definition namespace into a new dict. */
dict = PyDict_Copy(orig_dict);
if (dict == NULL)
goto error;
@@ -2559,6 +2580,48 @@
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 @@
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 @@
static PyObject *
type_prepare(PyObject *self, PyObject *args, PyObject *kwds)
{
- return PyDict_New();
+ return PyODict_New();
}
/*
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -145,7 +145,7 @@
if (prep == NULL) {
if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
PyErr_Clear();
- ns = PyDict_New();
+ ns = PyODict_New();
}
else {
Py_DECREF(meta);
--
Repository URL: https://hg.python.org/cpython
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