/Doc/library/anydbm.rst
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- :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 3.0. The
- :term:`2to3` tool will automatically adapt imports when converting your
- sources to 3.0.
- .. 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()
- .. 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.