*** Python-2.2.1/Lib/shelve.py	Tue May  7 10:03:58 2002
--- patched/shelve.py	Tue May  7 10:04:34 2002
***************
*** 26,31 ****
--- 26,43 ----
  
  Dependent on the implementation, closing a persistent dictionary may
  or may not be necessary to flush changes to disk.
+ 
+ If optional flag smart=1 is passed in the .open call, the resulting
+ object 'd' keeps an in-memory 'cache' of all data retrieved from it
+ or stored to it since it was opened.  Apart from speed issues, which
+ may cut either way, this ensures that a modifiable item may indeed
+ be modified *and have the modifications KNOWN to the shelf object it
+ comes from*.  WITHOUT smart=1:
+         d['spam'] = [1,2,3]   # ok
+         d['spam'].append(4)   # doesn't "take"!
+ the value at d['spam'] remains [1,2,3]: the .append modification is
+ done on a temporary object, NOT on the actual stored value!  WITH
+ smart=1, this behaves in a less surprising way.
  """
  
  # Try using cPickle and cStringIO if available.
***************
*** 49,56 ****
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, dict):
          self.dict = dict
  
      def keys(self):
          return self.dict.keys()
--- 61,70 ----
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, dict, smart=0):
          self.dict = dict
+         if smart:
+             self.cache = {}
  
      def keys(self):
          return self.dict.keys()
***************
*** 67,85 ****
          return default
  
      def __getitem__(self, key):
          f = StringIO(self.dict[key])
!         return Unpickler(f).load()
  
      def __setitem__(self, key, value):
          f = StringIO()
          p = Pickler(f)
          p.dump(value)
!         self.dict[key] = f.getvalue()
  
      def __delitem__(self, key):
          del self.dict[key]
  
      def close(self):
          try:
              self.dict.close()
          except:
--- 81,110 ----
          return default
  
      def __getitem__(self, key):
+         try: return self.cache[key]
+         except: pass
          f = StringIO(self.dict[key])
!         result = Unpickler(f).load()
!         try: self.cache[key] = result
!         except: pass
!         return result
  
      def __setitem__(self, key, value):
          f = StringIO()
          p = Pickler(f)
          p.dump(value)
!         result = f.getvalue()
!         self.dict[key] = result
!         try: self.cache[key] = result
!         except: pass
  
      def __delitem__(self, key):
          del self.dict[key]
+         try: del self.cache[key]
+         except: pass
  
      def close(self):
+         self.sync()
          try:
              self.dict.close()
          except:
***************
*** 90,95 ****
--- 115,127 ----
          self.close()
  
      def sync(self):
+         try: c=self.cache
+         except: pass
+         else:
+             del self.cache
+             for k in c:
+                 self[k] = c[k]
+             self.cache = {}
          if hasattr(self.dict, 'sync'):
              self.dict.sync()
  
***************
*** 107,114 ****
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, dict):
!         Shelf.__init__(self, dict)
  
      def set_location(self, key):
          (key, value) = self.dict.set_location(key)
--- 139,146 ----
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, dict, smart=0):
!         Shelf.__init__(self, dict, smart)
  
      def set_location(self, key):
          (key, value) = self.dict.set_location(key)
***************
*** 143,158 ****
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, filename, flag='c'):
          import anydbm
!         Shelf.__init__(self, anydbm.open(filename, flag))
  
  
! def open(filename, flag='c'):
      """Open a persistent dictionary for reading and writing.
  
      Argument is the filename for the dbm database.
      See the module's __doc__ string for an overview of the interface.
      """
  
!     return DbfilenameShelf(filename, flag)
--- 175,190 ----
      See the module's __doc__ string for an overview of the interface.
      """
  
!     def __init__(self, filename, flag='c', smart=0):
          import anydbm
!         Shelf.__init__(self, anydbm.open(filename, flag), smart)
  
  
! def open(filename, flag='c', smart=0):
      """Open a persistent dictionary for reading and writing.
  
      Argument is the filename for the dbm database.
      See the module's __doc__ string for an overview of the interface.
      """
  
!     return DbfilenameShelf(filename, flag, smart)