[Python-checkins] bpo-35864: Replace OrderedDict with regular dict in namedtuple() (#11708)
Raymond Hettinger
webhook-mailer at python.org
Thu Jan 31 03:59:56 EST 2019
https://github.com/python/cpython/commit/0bb4bdf0d93b301407774c4ffd6df54cff947df8
commit: 0bb4bdf0d93b301407774c4ffd6df54cff947df8
branch: master
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-01-31T00:59:50-08:00
summary:
bpo-35864: Replace OrderedDict with regular dict in namedtuple() (#11708)
* Change from OrderedDict to a regular dict
* Add blurb
files:
A Misc/NEWS.d/next/Library/2019-01-30-20-22-36.bpo-35864.ig9KnG.rst
M Doc/library/collections.rst
M Doc/whatsnew/3.8.rst
M Lib/collections/__init__.py
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index bfbf8a7ecc07..3fa8b32ff006 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -894,11 +894,18 @@ field names, the method and attribute names start with an underscore.
>>> p = Point(x=11, y=22)
>>> p._asdict()
- OrderedDict([('x', 11), ('y', 22)])
+ {'x': 11, 'y': 22}
.. versionchanged:: 3.1
Returns an :class:`OrderedDict` instead of a regular :class:`dict`.
+ .. versionchanged:: 3.8
+ Returns a regular :class:`dict` instead of an :class:`OrderedDict`.
+ As of Python 3.7, regular dicts are guaranteed to be ordered. If the
+ extra features of :class:`OrderedDict` are required, the suggested
+ remediation is to cast the result to the desired type:
+ ``OrderedDict(nt._asdict())``.
+
.. method:: somenamedtuple._replace(**kwargs)
Return a new instance of the named tuple replacing specified fields with new
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index fb25ce2f7669..09c43b1f30a5 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -125,6 +125,14 @@ New Modules
Improved Modules
================
+* The :meth:`_asdict()` method for :func:`collections.namedtuple` now returns
+ a :class:`dict` instead of a :class:`collections.OrderedDict`. This works because
+ regular dicts have guaranteed ordering in since Python 3.7. If the extra
+ features of :class:`OrderedDict` are required, the suggested remediation is
+ to cast the result to the desired type: ``OrderedDict(nt._asdict())``.
+ (Contributed by Raymond Hettinger in :issue:`35864`.)
+
+
asyncio
-------
diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index c31d7b79185d..835cc363d10a 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -426,9 +426,11 @@ def __repr__(self):
'Return a nicely formatted representation string'
return self.__class__.__name__ + repr_fmt % self
+ _dict, _zip = dict, zip
+
def _asdict(self):
'Return a new OrderedDict which maps field names to their values.'
- return OrderedDict(zip(self._fields, self))
+ return _dict(_zip(self._fields, self))
def __getnewargs__(self):
'Return self as a plain tuple. Used by copy and pickle.'
diff --git a/Misc/NEWS.d/next/Library/2019-01-30-20-22-36.bpo-35864.ig9KnG.rst b/Misc/NEWS.d/next/Library/2019-01-30-20-22-36.bpo-35864.ig9KnG.rst
new file mode 100644
index 000000000000..e3b41b700e6b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-01-30-20-22-36.bpo-35864.ig9KnG.rst
@@ -0,0 +1,2 @@
+The _asdict() method for collections.namedtuple now returns a regular dict
+instead of an OrderedDict.
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