From: Raymond Hettinger <python@rcn.com>
Date: Sat, 16 Apr 2011 00:43:19 +0000 (-0700)
Subject: Add another example to the collections module docs.
X-Git-Tag: v3.2.1b1~118^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7bba683d27a82856f93f72370f273025579d3a13;p=thirdparty%2FPython%2Fcpython.git

Add another example to the collections module docs.
---

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 02415f77353e..68a79f12d097 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -783,6 +783,9 @@ semantics pass-in keyword arguments using a regular unordered dictionary.
    `Equivalent OrderedDict recipe <http://code.activestate.com/recipes/576693/>`_
    that runs on Python 2.4 or later.
 
+:class:`OrderedDict` Examples and Recipes
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Since an ordered dictionary remembers its insertion order, it can be used
 in conjuction with sorting to make a sorted dictionary::
 
@@ -812,11 +815,28 @@ original insertion position is changed and moved to the end::
 
     class LastUpdatedOrderedDict(OrderedDict):
         'Store items in the order the keys were last added'
+
         def __setitem__(self, key, value):
             if key in self:
                 del self[key]
             OrderedDict.__setitem__(self, key, value)
 
+An ordered dictionary can combined with the :class:`Counter` class
+so that the counter remembers the order elements are first encountered::
+
+   class OrderedCounter(Counter, OrderedDict):
+        'Counter that remembers the order elements are first encountered'
+
+        def __init__(self, iterable=None, **kwds):
+            OrderedDict.__init__(self)
+            Counter.__init__(self, iterable, **kwds)
+
+        def __repr__(self):
+            return '%s(%r)' % (self.__class__.__name__, OrderedDict(self))
+
+        def __reduce__(self):
+            return self.__class__, (OrderedDict(self),)
+
 
 :class:`UserDict` objects
 -------------------------