src/gpodder/dumbshelve.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 # gPodder - A media aggregator and podcast client
   4 # Copyright (c) 2005-2008 Thomas Perl and the gPodder Team
   5 #
   6 # gPodder is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # gPodder is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 #
  19
  20 # dumbshelve.py - Temporary implementation of a shelve replacement
  21 # 2008-02-27 Thomas Perl <thpinfo.com>
  22
  23 from gpodder.liblogger import log
  24
  25 import UserDict
  26 import cPickle
  27 import os.path
  28
  29 class DumbShelve(UserDict.UserDict):
  30     """
  31     Simply tries to act like a "shelve" object..
  32     """
  33     def __init__(self, filename=None):
  34         UserDict.UserDict.__init__(self)
  35         self.__filename = filename
  36         self.__dirty = False
  37
  38     def sync(self, filename=None):
  39         if not self.__dirty:
  40             return True
  41
  42         if filename is not None:
  43             self.__filename = filename
  44         try:
  45             self.__dirty = False
  46             cPickle.dump(self, open(self.__filename, 'w'))
  47             return True
  48         except:
  49             log('Cannot pickle me to %s', self.__filename, sender=self, traceback=True)
  50             return False
  51
  52     def __setitem__(self, key, item):
  53         self.__dirty = True
  54         UserDict.UserDict.__setitem__(self, key, item)
  55
  56     def __delitem__(self, key):
  57         self.__dirty = True
  58         UserDict.UserDict.__delitem__(self, key)
  59
  60 def open_shelve(filename):
  61     if not os.path.exists(filename):
  62         return DumbShelve(filename)
  63     else:
  64         try:
  65             return cPickle.load(open(filename, 'r'))
  66         except:
  67             log('Error loading %s. Creating new DumbShelve.', filename, traceback=True)
  68             return DumbShelve(filename)
  69