Lib/anydbm.py

   1 """A generic interface to all dbm clones.
   2
   3 Instead of
   4
   5         import dbm
   6         d = dbm.open(file, 'rw', 0666)
   7
   8 use
   9
  10         import anydbm
  11         d = anydbm.open(file)
  12
  13 The returned object is a dbm, gdbm or (on the Mac) dbmac 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 db-like implementations
  29 (e.g. BSD Hash), 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.  Don't pas an explicit 'w'
  35 or 'rw' to open it for writing, as the different interfaces have
  36 different interpretation of their mode argument if it isn't 'r'.
  37 """
  38
  39 try:
  40         import dbm
  41         def open(filename, mode = 'rw'):
  42                 return dbm.open(filename, mode, 0666)
  43 except ImportError:
  44         try:
  45                 import gdbm
  46                 def open(filename, mode = 'w'):
  47                         return gdbm.open(filename, mode, 0666)
  48         except ImportError:
  49                 import dbmac
  50                 open = dbmac.open