Issue 5754: tweak shelve doc wording to make it clearer that even when
writeback=True values are written to the backing store when assigned to
the shelf. Add test to confirm that this happens. Doc patch and added
test by Robert Lehmann. I also fixed the cross references to the sync
and close methods.
diff --git a/Doc/library/shelve.rst b/Doc/library/shelve.rst
index 5d82dc4..c0bcb80 100644
--- a/Doc/library/shelve.rst
+++ b/Doc/library/shelve.rst
@@ -30,14 +30,15 @@
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 3b20281..df56625 100644
--- a/Lib/test/test_shelve.py
+++ b/Lib/test/test_shelve.py
@@ -90,6 +90,17 @@
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 0ce586e..b389f77 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -444,6 +444,7 @@
Vincent Legoll
Kip Lehman
Joerg Lehmann
+Robert Lehmann
Luke Kenneth Casson Leighton
Marc-Andre Lemburg
John Lenton