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