Use cPickle and cStringIO when available.

diff --git a/Lib/shelve.py b/Lib/shelve.py
index 8f709a233a0c08bfc6718cda9d9621d82393b89c..b159e61380794a82db2cdd60d6c8c26f577f278f 100644 (file)
--- a/Lib/shelve.py
+++ b/Lib/shelve.py
@@ -28,8 +28,17 @@ Dependent on the implementation, closing a persistent dictionary may
 or may not be necessary to flush changes to disk.
 """
 
-import pickle
-import StringIO
+# Try using cPickle and cStringIO if available.
+
+try:
+    from cPickle import Pickler, Unpickler
+except ImportError:
+    from pickle import Pickler, Unpickler
+
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
 
 
 class Shelf:
@@ -52,12 +61,12 @@ class Shelf:
                return self.dict.has_key(key)
        
        def __getitem__(self, key):
-               f = StringIO.StringIO(self.dict[key])
-               return pickle.Unpickler(f).load()
+               f = StringIO(self.dict[key])
+               return Unpickler(f).load()
        
        def __setitem__(self, key, value):
-               f = StringIO.StringIO()
-               p = pickle.Pickler(f)
+               f = StringIO()
+               p = Pickler(f)
                p.dump(value)
                self.dict[key] = f.getvalue()
        
@@ -80,11 +89,12 @@ class Shelf:
 class BsdDbShelf(Shelf):
        """Shelf implementation using the "BSD" db interface.
 
-       The actual database is opened using one of thethe "bsddb" modules
-       "open" routines (i.e. bsddb.hashopen, bsddb.btopen or bsddb.rnopen.)
+       This adds methods first(), next(), previous(), last() and
+       set_location() that have no counterpart in [g]dbm databases.
 
-       This class is initialized with the the database object
-       returned from one of the bsddb open functions.
+       The actual database must be opened using one of the "bsddb"
+       modules "open" routines (i.e. bsddb.hashopen, bsddb.btopen or
+       bsddb.rnopen) and passed to the constructor.
 
        See the module's __doc__ string for an overview of the interface.
        """
@@ -94,28 +104,28 @@ class BsdDbShelf(Shelf):
 
        def set_location(self, key):
             (key, value) = self.dict.set_location(key)
-            f = StringIO.StringIO(value)
-            return (key, pickle.Unpickler(f).load())
+            f = StringIO(value)
+            return (key, Unpickler(f).load())
 
        def next(self):
             (key, value) = self.dict.next()
-            f = StringIO.StringIO(value)
-            return (key, pickle.Unpickler(f).load())
+            f = StringIO(value)
+            return (key, Unpickler(f).load())
 
        def previous(self):
             (key, value) = self.dict.previous()
-            f = StringIO.StringIO(value)
-            return (key, pickle.Unpickler(f).load())
+            f = StringIO(value)
+            return (key, Unpickler(f).load())
 
        def first(self):
             (key, value) = self.dict.first()
-            f = StringIO.StringIO(value)
-            return (key, pickle.Unpickler(f).load())
+            f = StringIO(value)
+            return (key, Unpickler(f).load())
 
        def last(self):
             (key, value) = self.dict.last()
-            f = StringIO.StringIO(value)
-            return (key, pickle.Unpickler(f).load())
+            f = StringIO(value)
+            return (key, Unpickler(f).load())
 
 
 class DbfilenameShelf(Shelf):