1:mod:`anydbm` --- Generic access to DBM-style databases 2======================================================= 3 4.. module:: anydbm 5 :synopsis: Generic interface to DBM-style database modules. 6 7 8.. note:: 9 The :mod:`anydbm` module has been renamed to :mod:`dbm` in Python 3. The 10 :term:`2to3` tool will automatically adapt imports when converting your 11 sources to Python 3. 12 13.. index:: 14 module: dbhash 15 module: bsddb 16 module: gdbm 17 module: dbm 18 module: dumbdbm 19 20:mod:`anydbm` is a generic interface to variants of the DBM database --- 21:mod:`dbhash` (requires :mod:`bsddb`), :mod:`gdbm`, or :mod:`dbm`. If none of 22these modules is installed, the slow-but-simple implementation in module 23:mod:`dumbdbm` will be used. 24 25 26.. function:: open(filename[, flag[, mode]]) 27 28 Open the database file *filename* and return a corresponding object. 29 30 If the database file already exists, the :mod:`whichdb` module is used to 31 determine its type and the appropriate module is used; if it does not exist, 32 the first module listed above that can be imported is used. 33 34 The optional *flag* argument must be one of these values: 35 36 +---------+-------------------------------------------+ 37 | Value | Meaning | 38 +=========+===========================================+ 39 | ``'r'`` | Open existing database for reading only | 40 | | (default) | 41 +---------+-------------------------------------------+ 42 | ``'w'`` | Open existing database for reading and | 43 | | writing | 44 +---------+-------------------------------------------+ 45 | ``'c'`` | Open database for reading and writing, | 46 | | creating it if it doesn't exist | 47 +---------+-------------------------------------------+ 48 | ``'n'`` | Always create a new, empty database, open | 49 | | for reading and writing | 50 +---------+-------------------------------------------+ 51 52 If not specified, the default value is ``'r'``. 53 54 The optional *mode* argument is the Unix mode of the file, used only when the 55 database has to be created. It defaults to octal ``0666`` (and will be 56 modified by the prevailing umask). 57 58 59.. exception:: error 60 61 A tuple containing the exceptions that can be raised by each of the supported 62 modules, with a unique exception also named :exc:`anydbm.error` as the first 63 item --- the latter is used when :exc:`anydbm.error` is raised. 64 65The object returned by :func:`.open` supports most of the same functionality as 66dictionaries; keys and their corresponding values can be stored, retrieved, and 67deleted, and the :meth:`has_key` and :meth:`keys` methods are available. Keys 68and values must always be strings. 69 70The following example records some hostnames and a corresponding title, and 71then prints out the contents of the database:: 72 73 import anydbm 74 75 # Open database, creating it if necessary. 76 db = anydbm.open('cache', 'c') 77 78 # Record some values 79 db['www.python.org'] = 'Python Website' 80 db['www.cnn.com'] = 'Cable News Network' 81 82 # Loop through contents. Other dictionary methods 83 # such as .keys(), .values() also work. 84 for k, v in db.iteritems(): 85 print k, '\t', v 86 87 # Storing a non-string key or value will raise an exception (most 88 # likely a TypeError). 89 db['www.yahoo.com'] = 4 90 91 # Close when done. 92 db.close() 93 94 95In addition to the dictionary-like methods, ``anydbm`` objects 96provide the following method: 97 98.. function:: close() 99 100 Close the ``anydbm`` database. 101 102 103.. seealso:: 104 105 Module :mod:`dbhash` 106 BSD ``db`` database interface. 107 108 Module :mod:`dbm` 109 Standard Unix database interface. 110 111 Module :mod:`dumbdbm` 112 Portable implementation of the ``dbm`` interface. 113 114 Module :mod:`gdbm` 115 GNU database interface, based on the ``dbm`` interface. 116 117 Module :mod:`shelve` 118 General object persistence built on top of the Python ``dbm`` interface. 119 120 Module :mod:`whichdb` 121 Utility module used to determine the type of an existing database. 122 123