From 4e0172fd9acf7c5e8f30905fc997f904adbe562f Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Fri, 17 May 2013 17:14:27 -0700
Subject: [PATCH] Deprecate nametuple._asdict()

---
 Doc/library/collections.rst  | 7 +++++--
 Lib/collections/__init__.py  | 3 +++
 Lib/test/test_collections.py | 7 +++++--
 Misc/NEWS                    | 3 +++
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 96c5aef0371..70637687d33 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -829,6 +829,9 @@ field names, the method and attribute names start with an underscore.
     .. versionchanged:: 3.1
         Returns an :class:`OrderedDict` instead of a regular :class:`dict`.
 
+    .. deprecated:: 3.4
+       Use ``vars(nt)`` or ``nt.__dict__`` instead.
+
 .. method:: somenamedtuple._replace(kwargs)
 
     Return a new instance of the named tuple replacing specified fields with new
@@ -845,8 +848,8 @@ field names, the method and attribute names start with an underscore.
 
     A string with the pure Python source code used to create the named
     tuple class.  The source makes the named tuple self-documenting.
-    It can be printed, executed using :func:`exec`, or saved to a file
-    and imported.
+    It can be printed, executed using :func:`exec`, customized, or saved
+    to a file and imported.
 
     .. versionadded:: 3.3
 
diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index 5fd54e8d4cb..24daa34b4c2 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -280,6 +280,9 @@ class {typename}(tuple):
         '''Return a new OrderedDict which maps field names to their values.
            This method is obsolete.  Use vars(nt) or nt.__dict__ instead.
         '''
+        import warnings
+        warnings.warn('_asdict() is deprecated.  Use vars(nt) instead.',
+                      DeprecationWarning, stacklevel=2)
         return self.__dict__
 
     def __getnewargs__(self):
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 80330312594..12bd952e3f9 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -217,8 +217,11 @@ class TestNamedTuple(unittest.TestCase):
         self.assertEqual(p, Point._make([11, 22]))                          # test _make classmethod
         self.assertEqual(p._fields, ('x', 'y'))                             # test _fields attribute
         self.assertEqual(p._replace(x=1), (1, 22))                          # test _replace method
-        self.assertEqual(p._asdict(), dict(x=11, y=22))                     # test _asdict method
-        self.assertEqual(vars(p), p._asdict())                              # verify that vars() works
+        self.assertEqual(p.__dict__,
+                         OrderedDict([('x', 11), ('y', 22)]))               # test __dict__ attribute
+        self.assertEqual(vars(p), p.__dict__)                               # verify that vars() works
+        with self.assertWarns(DeprecationWarning):                          # check deprecate of _asdict
+            p._asdict()
 
         try:
             p._replace(x=1, error=2)
diff --git a/Misc/NEWS b/Misc/NEWS
index 68902e5c1fe..20bf8b11c2e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -96,6 +96,9 @@ Library
 
 - Issue #15758: Fix FileIO.readall() so it no longer has O(n**2) complexity.
 
+- Deprecated the _asdict() method on named tuples.  Use __dict__ or vars(nt)
+  instead.
+
 - Issue #14596: The struct.Struct() objects now use more compact implementation.
 
 - Issue #17981: Closed socket on error in SysLogHandler.