diff --git a/Doc/library/shelve.rst b/Doc/library/shelve.rst index 5d82dc42d54..c0bcb80f190 100644 --- a/Doc/library/shelve.rst +++ b/Doc/library/shelve.rst @@ -30,14 +30,15 @@ lots of shared sub-objects. The keys are ordinary strings. Because of Python semantics, a shelf cannot know when a mutable persistent-dictionary entry is modified. By default modified objects are - written only when assigned to the shelf (see :ref:`shelve-example`). If the - optional *writeback* parameter is set to *True*, all entries accessed are - cached in memory, and written back on :meth:`sync` and :meth:`close`; this - can make it handier to mutate mutable entries in the persistent dictionary, - but, if many entries are accessed, it can consume vast amounts of memory for - the cache, and it can make the close operation very slow since all accessed - entries are written back (there is no way to determine which accessed entries - are mutable, nor which ones were actually mutated). + written *only* when assigned to the shelf (see :ref:`shelve-example`). If the + optional *writeback* parameter is set to *True*, all entries accessed are also + cached in memory, and written back on :meth:`~Shelf.sync` and + :meth:`~Shelf.close`; this can make it handier to mutate mutable entries in + the persistent dictionary, but, if many entries are accessed, it can consume + vast amounts of memory for the cache, and it can make the close operation + very slow since all accessed entries are written back (there is no way to + determine which accessed entries are mutable, nor which ones were actually + mutated). .. note:: diff --git a/Lib/test/test_shelve.py b/Lib/test/test_shelve.py index 3b20281a02b..df56625a599 100644 --- a/Lib/test/test_shelve.py +++ b/Lib/test/test_shelve.py @@ -90,6 +90,17 @@ class TestCase(unittest.TestCase): self.assertEqual(len(d1), 1) self.assertEqual(len(d2), 1) + def test_writeback_also_writes_immediately(self): + # Issue 5754 + d = {} + s = shelve.Shelf(d, writeback=True) + s['key'] = [1] + p1 = d['key'] # Will give a KeyError if backing store not updated + s['key'].append(2) + s.close() + p2 = d['key'] + self.assertNotEqual(p1, p2) # Write creates new object in store + from test import mapping_tests diff --git a/Misc/ACKS b/Misc/ACKS index 0ce586eb4e9..b389f775d9f 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -444,6 +444,7 @@ Luc Lefebvre Vincent Legoll Kip Lehman Joerg Lehmann +Robert Lehmann Luke Kenneth Casson Leighton Marc-Andre Lemburg John Lenton