Close #19282: Native context management in dbm
diff --git a/Doc/library/dbm.rst b/Doc/library/dbm.rst
index 81a05c7..f5496d5 100644
--- a/Doc/library/dbm.rst
+++ b/Doc/library/dbm.rst
@@ -73,33 +73,39 @@
strings are used they are implicitly converted to the default encoding before
being stored.
+These objects also support being used in a :keyword:`with` statement, which
+will automatically close them when done.
+
+.. versionchanged:: 3.4
+ Added native support for the context management protocol to the objects
+ returned by :func:`.open`.
+
The following example records some hostnames and a corresponding title, and
then prints out the contents of the database::
import dbm
# Open database, creating it if necessary.
- db = dbm.open('cache', 'c')
+ with dbm.open('cache', 'c') as db:
- # Record some values
- db[b'hello'] = b'there'
- db['www.python.org'] = 'Python Website'
- db['www.cnn.com'] = 'Cable News Network'
+ # Record some values
+ db[b'hello'] = b'there'
+ db['www.python.org'] = 'Python Website'
+ db['www.cnn.com'] = 'Cable News Network'
- # Note that the keys are considered bytes now.
- assert db[b'www.python.org'] == b'Python Website'
- # Notice how the value is now in bytes.
- assert db['www.cnn.com'] == b'Cable News Network'
+ # Note that the keys are considered bytes now.
+ assert db[b'www.python.org'] == b'Python Website'
+ # Notice how the value is now in bytes.
+ assert db['www.cnn.com'] == b'Cable News Network'
- # Often-used methods of the dict interface work too.
- print(db.get('python.org', b'not present'))
+ # Often-used methods of the dict interface work too.
+ print(db.get('python.org', b'not present'))
- # Storing a non-string key or value will raise an exception (most
- # likely a TypeError).
- db['www.yahoo.com'] = 4
+ # Storing a non-string key or value will raise an exception (most
+ # likely a TypeError).
+ db['www.yahoo.com'] = 4
- # Close when done.
- db.close()
+ # db is automatically closed when leaving the with statement.
.. seealso::
diff --git a/Lib/dbm/dumb.py b/Lib/dbm/dumb.py
index 9ac7852..ba6a20d 100644
--- a/Lib/dbm/dumb.py
+++ b/Lib/dbm/dumb.py
@@ -236,6 +236,12 @@
if hasattr(self._os, 'chmod'):
self._os.chmod(file, self._mode)
+ def __enter__(self):
+ return self
+
+ def __exit__(self, *args):
+ self.close()
+
def open(file, flag=None, mode=0o666):
"""Open the database file, filename, and return corresponding object.
diff --git a/Lib/test/test_dbm_dumb.py b/Lib/test/test_dbm_dumb.py
index 208bc4c..9fd8cde 100644
--- a/Lib/test/test_dbm_dumb.py
+++ b/Lib/test/test_dbm_dumb.py
@@ -184,6 +184,19 @@
self.assertEqual(expected, got)
f.close()
+ def test_context_manager(self):
+ with dumbdbm.open(_fname, 'c') as db:
+ db["dumbdbm context manager"] = "context manager"
+
+ with dumbdbm.open(_fname, 'r') as db:
+ self.assertEqual(list(db.keys()), [b"dumbdbm context manager"])
+
+ # This currently just raises AttributeError rather than a specific
+ # exception like the GNU or NDBM based implementations. See
+ # http://bugs.python.org/issue19385 for details.
+ with self.assertRaises(Exception):
+ db.keys()
+
def tearDown(self):
_delete_files()
diff --git a/Lib/test/test_dbm_gnu.py b/Lib/test/test_dbm_gnu.py
index 4fb66c5..a7808f5 100755
--- a/Lib/test/test_dbm_gnu.py
+++ b/Lib/test/test_dbm_gnu.py
@@ -81,6 +81,17 @@
size2 = os.path.getsize(filename)
self.assertTrue(size1 > size2 >= size0)
+ def test_context_manager(self):
+ with gdbm.open(filename, 'c') as db:
+ db["gdbm context manager"] = "context manager"
+
+ with gdbm.open(filename, 'r') as db:
+ self.assertEqual(list(db.keys()), [b"gdbm context manager"])
+
+ with self.assertRaises(gdbm.error) as cm:
+ db.keys()
+ self.assertEqual(str(cm.exception),
+ "GDBM object has already been closed")
if __name__ == '__main__':
unittest.main()
diff --git a/Lib/test/test_dbm_ndbm.py b/Lib/test/test_dbm_ndbm.py
index b57e1f0..2291561 100755
--- a/Lib/test/test_dbm_ndbm.py
+++ b/Lib/test/test_dbm_ndbm.py
@@ -37,5 +37,18 @@
except error:
self.fail()
+ def test_context_manager(self):
+ with dbm.ndbm.open(self.filename, 'c') as db:
+ db["ndbm context manager"] = "context manager"
+
+ with dbm.ndbm.open(self.filename, 'r') as db:
+ self.assertEqual(list(db.keys()), [b"ndbm context manager"])
+
+ with self.assertRaises(dbm.ndbm.error) as cm:
+ db.keys()
+ self.assertEqual(str(cm.exception),
+ "DBM object has already been closed")
+
+
if __name__ == '__main__':
unittest.main()
diff --git a/Misc/NEWS b/Misc/NEWS
index 89c37d9..9dedb6a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -50,6 +50,9 @@
Library
-------
+- Issue #19282: dbm.open now supports the context manager protocol. (Inital
+ patch by Claudiu Popa)
+
- Issue #8311: Added support for writing any bytes-like objects in the aifc,
sunau, and wave modules.
diff --git a/Modules/_dbmmodule.c b/Modules/_dbmmodule.c
index 60802b6..370f670 100644
--- a/Modules/_dbmmodule.c
+++ b/Modules/_dbmmodule.c
@@ -313,6 +313,21 @@
return defvalue;
}
+static PyObject *
+dbm__enter__(PyObject *self, PyObject *args)
+{
+ Py_INCREF(self);
+ return self;
+}
+
+static PyObject *
+dbm__exit__(PyObject *self, PyObject *args)
+{
+ _Py_IDENTIFIER(close);
+ return _PyObject_CallMethodId(self, &PyId_close, NULL);
+}
+
+
static PyMethodDef dbm_methods[] = {
{"close", (PyCFunction)dbm__close, METH_NOARGS,
"close()\nClose the database."},
@@ -325,6 +340,8 @@
"setdefault(key[, default]) -> value\n"
"Return the value for key if present, otherwise default. If key\n"
"is not in the database, it is inserted with default as the value."},
+ {"__enter__", dbm__enter__, METH_NOARGS, NULL},
+ {"__exit__", dbm__exit__, METH_VARARGS, NULL},
{NULL, NULL} /* sentinel */
};
diff --git a/Modules/_gdbmmodule.c b/Modules/_gdbmmodule.c
index 36c06d1..229e16e 100644
--- a/Modules/_gdbmmodule.c
+++ b/Modules/_gdbmmodule.c
@@ -425,6 +425,20 @@
return Py_None;
}
+static PyObject *
+dbm__enter__(PyObject *self, PyObject *args)
+{
+ Py_INCREF(self);
+ return self;
+}
+
+static PyObject *
+dbm__exit__(PyObject *self, PyObject *args)
+{
+ _Py_IDENTIFIER(close);
+ return _PyObject_CallMethodId(self, &PyId_close, NULL);
+}
+
static PyMethodDef dbm_methods[] = {
{"close", (PyCFunction)dbm_close, METH_NOARGS, dbm_close__doc__},
{"keys", (PyCFunction)dbm_keys, METH_NOARGS, dbm_keys__doc__},
@@ -434,6 +448,8 @@
{"sync", (PyCFunction)dbm_sync, METH_NOARGS, dbm_sync__doc__},
{"get", (PyCFunction)dbm_get, METH_VARARGS, dbm_get__doc__},
{"setdefault",(PyCFunction)dbm_setdefault,METH_VARARGS, dbm_setdefault__doc__},
+ {"__enter__", dbm__enter__, METH_NOARGS, NULL},
+ {"__exit__", dbm__exit__, METH_VARARGS, NULL},
{NULL, NULL} /* sentinel */
};