diff options
| -rw-r--r-- | Doc/library/collections.rst | 12 | ||||
| -rw-r--r-- | Lib/collections.py | 6 | ||||
| -rw-r--r-- | Lib/test/test_collections.py | 7 |
3 files changed, 20 insertions, 5 deletions
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst index d6d1b68..32375a2 100644 --- a/Doc/library/collections.rst +++ b/Doc/library/collections.rst @@ -858,8 +858,11 @@ the items are returned in the order their keys were first added. .. versionadded:: 2.7 -The :meth:`popitem` method for ordered dictionaries returns and removes the -last added entry. The key/value pairs are returned in LIFO order. +.. method:: OrderedDict.popitem(last=True) + + The :meth:`popitem` method for ordered dictionaries returns and removes + a (key, value) pair. The pairs are returned in LIFO order if *last* is + true or FIFO order if false. Equality tests between :class:`OrderedDict` objects are order-sensitive and are implemented as ``list(od1.items())==list(od2.items())``. @@ -867,3 +870,8 @@ Equality tests between :class:`OrderedDict` objects and other :class:`Mapping` objects are order-insensitive like regular dictionaries. This allows :class:`OrderedDict` objects to be substituted anywhere a regular dictionary is used. + +.. seealso:: + + `Equivalent OrderedDict recipe <http://code.activestate.com/recipes/576693/>`_ + that runs on Python 2.4 or later. diff --git a/Lib/collections.py b/Lib/collections.py index 1193ebf..8c0b426 100644 --- a/Lib/collections.py +++ b/Lib/collections.py @@ -30,7 +30,7 @@ class OrderedDict(dict, MutableMapping): def clear(self): self.__end = end = [] - end += [None, end, end] # null entry + end += [None, end, end] # sentinel node for doubly linked list self.__map = {} # key --> [key, prev, next] dict.clear(self) @@ -61,10 +61,10 @@ class OrderedDict(dict, MutableMapping): yield curr[0] curr = curr[1] - def popitem(self): + def popitem(self, last=True): if not self: raise KeyError('dictionary is empty') - key = next(reversed(self)) + key = next(reversed(self)) if last else next(iter(self)) value = self.pop(key) return key, value diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py index f232df4..9e984ba 100644 --- a/Lib/test/test_collections.py +++ b/Lib/test/test_collections.py @@ -768,12 +768,19 @@ class TestOrderedDict(unittest.TestCase): class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol): type2test = OrderedDict + def test_popitem(self): + d = self._empty_mapping() + self.assertRaises(KeyError, d.popitem) + class MyOrderedDict(OrderedDict): pass class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol): type2test = MyOrderedDict + def test_popitem(self): + d = self._empty_mapping() + self.assertRaises(KeyError, d.popitem) import doctest, collections |