:mod:`anydbm` --- Generic access to DBM-style databases ======================================================= .. module:: anydbm :synopsis: Generic interface to DBM-style database modules. .. note:: The :mod:`anydbm` module has been renamed to :mod:`dbm` in Python 3. The :term:`2to3` tool will automatically adapt imports when converting your sources to Python 3. .. index:: module: dbhash module: bsddb module: gdbm module: dbm module: dumbdbm :mod:`anydbm` is a generic interface to variants of the DBM database --- :mod:`dbhash` (requires :mod:`bsddb`), :mod:`gdbm`, or :mod:`dbm`. If none of these modules is installed, the slow-but-simple implementation in module :mod:`dumbdbm` will be used. .. function:: open(filename[, flag[, mode]]) Open the database file *filename* and return a corresponding object. If the database file already exists, the :mod:`whichdb` module is used to determine its type and the appropriate module is used; if it does not exist, the first module listed above that can be imported is used. The optional *flag* argument must be one of these values: +---------+-------------------------------------------+ | Value | Meaning | +=========+===========================================+ | ``'r'`` | Open existing database for reading only | | | (default) | +---------+-------------------------------------------+ | ``'w'`` | Open existing database for reading and | | | writing | +---------+-------------------------------------------+ | ``'c'`` | Open database for reading and writing, | | | creating it if it doesn't exist | +---------+-------------------------------------------+ | ``'n'`` | Always create a new, empty database, open | | | for reading and writing | +---------+-------------------------------------------+ If not specified, the default value is ``'r'``. The optional *mode* argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal ``0666`` (and will be modified by the prevailing umask). .. exception:: error A tuple containing the exceptions that can be raised by each of the supported modules, with a unique exception also named :exc:`anydbm.error` as the first item --- the latter is used when :exc:`anydbm.error` is raised. The object returned by :func:`.open` supports most of the same functionality as dictionaries; keys and their corresponding values can be stored, retrieved, and deleted, and the :meth:`has_key` and :meth:`keys` methods are available. Keys and values must always be strings. The following example records some hostnames and a corresponding title, and then prints out the contents of the database:: import anydbm # Open database, creating it if necessary. db = anydbm.open('cache', 'c') # Record some values db['www.python.org'] = 'Python Website' db['www.cnn.com'] = 'Cable News Network' # Loop through contents. Other dictionary methods # such as .keys(), .values() also work. for k, v in db.iteritems(): print k, '\t', v # Storing a non-string key or value will raise an exception (most # likely a TypeError). db['www.yahoo.com'] = 4 # Close when done. db.close() In addition to the dictionary-like methods, ``anydbm`` objects provide the following method: .. function:: close() Close the ``anydbm`` database. .. seealso:: Module :mod:`dbhash` BSD ``db`` database interface. Module :mod:`dbm` Standard Unix database interface. Module :mod:`dumbdbm` Portable implementation of the ``dbm`` interface. Module :mod:`gdbm` GNU database interface, based on the ``dbm`` interface. Module :mod:`shelve` General object persistence built on top of the Python ``dbm`` interface. Module :mod:`whichdb` Utility module used to determine the type of an existing database.