Demo/classes/Dbm.py

   1 # A wrapper around the (optional) built-in class dbm, supporting keys
   2 # and values of almost any type instead of just string.
   3 # (Actually, this works only for keys and values that can be read back
   4 # correctly after being converted to a string.)
   5
   6
   7 class Dbm:
   8
   9     def __init__(self, filename, mode, perm):
  10         import dbm
  11         self.db = dbm.open(filename, mode, perm)
  12
  13     def __repr__(self):
  14         s = ''
  15         for key in self.keys():
  16             t = repr(key) + ': ' + repr(self[key])
  17             if s: t = ', ' + t
  18             s = s + t
  19         return '{' + s + '}'
  20
  21     def __len__(self):
  22         return len(self.db)
  23
  24     def __getitem__(self, key):
  25         return eval(self.db[repr(key)])
  26
  27     def __setitem__(self, key, value):
  28         self.db[repr(key)] = repr(value)
  29
  30     def __delitem__(self, key):
  31         del self.db[repr(key)]
  32
  33     def keys(self):
  34         res = []
  35         for key in self.db.keys():
  36             res.append(eval(key))
  37         return res
  38
  39     def has_key(self, key):
  40         return self.db.has_key(repr(key))
  41
  42
  43 def test():
  44     d = Dbm('@dbm', 'rw', 0600)
  45     print d
  46     while 1:
  47         try:
  48             key = input('key: ')
  49             if d.has_key(key):
  50                 value = d[key]
  51                 print 'currently:', value
  52             value = input('value: ')
  53             if value == None:
  54                 del d[key]
  55             else:
  56                 d[key] = value
  57         except KeyboardInterrupt:
  58             print ''
  59             print d
  60         except EOFError:
  61             print '[eof]'
  62             break
  63     print d
  64
  65
  66 test()