#17040: document that shelve.open() and the Shelf object can be used as context…

#17040: document that shelve.open() and the Shelf object can be used as context managers.  Initial patch by Berker Peksag.

Doc/library/shelve.rst

@@ -44,8 +44,11 @@ lots of shared  sub-objects.  The keys are ordinary strings.
    .. note::
 
       Do not rely on the shelf being closed automatically; always call
-      :meth:`close` explicitly when you don't need it any more, or use a
-      :keyword:`with` statement with :func:`contextlib.closing`.
+      :meth:`~Shelf.close` explicitly when you don't need it any more, or
+      use :func:`shelve.open` as a context manager::
+
+          with shelve.open('spam') as db:
+              db['eggs'] = 'eggs'
 
 .. warning::
 
@@ -118,10 +121,15 @@ Restrictions
    The *keyencoding* parameter is the encoding used to encode keys before they
    are used with the underlying dict.
 
-   .. versionadded:: 3.2
-      The *keyencoding* parameter; previously, keys were always encoded in
+   :class:`Shelf` objects can also be used as context managers.
+
+   .. versionchanged:: 3.2
+      Added the *keyencoding* parameter; previously, keys were always encoded in
       UTF-8.
 
+   .. versionchanged:: 3.4
+      Added context manager support.
+
 
 .. class:: BsdDbShelf(dict, protocol=None, writeback=False, keyencoding='utf-8')