[Python-checkins] cpython: Issue #13896: Make shelf instances work with 'with' as context managers.

[andrew.svetlov]

http://hg.python.org/cpython/rev/3c1df1ede882
changeset:   79507:3c1df1ede882
user:        Andrew Svetlov <andrew.svetlov at gmail.com>
date:        Sat Oct 06 13:52:19 2012 +0300
summary:
  Issue #13896: Make shelf instances work with 'with' as context managers.

Original patch by Filip Gruszczyński.

files:
  Lib/shelve.py           |   7 +++++++
  Lib/test/test_shelve.py |  13 +++++++++++++
  Misc/NEWS               |   3 +++
  3 files changed, 23 insertions(+), 0 deletions(-)


diff --git a/Lib/shelve.py b/Lib/shelve.py
--- a/Lib/shelve.py
+++ b/Lib/shelve.py
@@ -131,6 +131,12 @@
         except KeyError:
             pass
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.close()
+
     def close(self):
         self.sync()
         try:
@@ -147,6 +153,7 @@
     def __del__(self):
         if not hasattr(self, 'writeback'):
             # __init__ didn't succeed, so don't bother closing
+            # see http://bugs.python.org/issue1339007 for details
             return
         self.close()
 
diff --git a/Lib/test/test_shelve.py b/Lib/test/test_shelve.py
--- a/Lib/test/test_shelve.py
+++ b/Lib/test/test_shelve.py
@@ -148,6 +148,19 @@
         p2 = d[encodedkey]
         self.assertNotEqual(p1, p2)  # Write creates new object in store
 
+    def test_with(self):
+        d1 = {}
+        with shelve.Shelf(d1, protocol=2, writeback=False) as s:
+            s['key1'] = [1,2,3,4]
+            self.assertEqual(s['key1'], [1,2,3,4])
+            self.assertEqual(len(s), 1)
+        self.assertRaises(ValueError, len, s)
+        try:
+            s['key1']
+        except ValueError:
+            pass
+        else:
+            self.fail('Closed shelf should not find a key')
 
 from test import mapping_tests
 
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -39,6 +39,9 @@
 Library
 -------
 
+- Issue #13896: Make shelf instances work with 'with' as context managers.
+  Original patch by Filip Gruszczyński.
+
 - Issue #15417: Add support for csh and fish in venv activation scripts.
 
 - Issue #16123: IDLE - deprecate running without a subprocess.

-- 
Repository URL: http://hg.python.org/cpython