Lib/anydbm.py

   1 """Generic interface to all dbm clones.
   2
   3 Instead of
   4
   5         import dbm
   6         d = dbm.open(file, 'w', 0666)
   7
   8 use
   9
  10         import anydbm
  11         d = anydbm.open(file)
  12
  13 The returned object is a dbhash, gdbm, dbm or dumbdbm object,
  14 dependent on availability of the modules (tested in this order).
  15
  16 It has the following interface (key and data are strings):
  17
  18         d[key] = data   # store data at key (may override data at
  19                         # existing key)
  20         data = d[key]   # retrieve data at key (raise KeyError if no
  21                         # such key)
  22         del d[key]      # delete data stored at key (raises KeyError
  23                         # if no such key)
  24         flag = d.has_key(key)   # true if the key exists
  25         list = d.keys() # return a list of all existing keys (slow!)
  26
  27 Future versions may change the order in which implementations are
  28 tested for existence, add interfaces to other dbm-like
  29 implementations, and (in the presence of multiple implementations)
  30 decide which module to use based upon the extension or contents of an
  31 existing database file.
  32
  33 The open function has an optional second argument.  This can be set to
  34 'r' to open the database for reading only.  The default is 'r', like
  35 the dbm default.
  36
  37 """
  38
  39 _names = ['dbhash', 'gdbm', 'dbm', 'dumbdbm']
  40
  41 for _name in _names:
  42         try:
  43                 exec "import %s; _mod = %s" % (_name, _name)
  44         except ImportError:
  45                 continue
  46         else:
  47                 break
  48 else:
  49         raise ImportError, "no dbm clone found; tried %s" % _names
  50
  51 error = _mod.error
  52
  53 def open(file, flag = 'r', mode = 0666):
  54         return _mod.open(file, flag, mode)