/Doc/library/dumbdbm.rst
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1:mod:`dumbdbm` --- Portable DBM implementation 2============================================== 3 4.. module:: dumbdbm 5 :synopsis: Portable implementation of the simple DBM interface. 6 7.. note:: 8 The :mod:`dumbdbm` module has been renamed to :mod:`dbm.dumb` in Python 3.0. 9 The :term:`2to3` tool will automatically adapt imports when converting your 10 sources to 3.0. 11 12.. index:: single: databases 13 14.. note:: 15 16 The :mod:`dumbdbm` module is intended as a last resort fallback for the 17 :mod:`anydbm` module when no more robust module is available. The :mod:`dumbdbm` 18 module is not written for speed and is not nearly as heavily used as the other 19 database modules. 20 21The :mod:`dumbdbm` module provides a persistent dictionary-like interface which 22is written entirely in Python. Unlike other modules such as :mod:`gdbm` and 23:mod:`bsddb`, no external library is required. As with other persistent 24mappings, the keys and values must always be strings. 25 26The module defines the following: 27 28 29.. exception:: error 30 31 Raised on dumbdbm-specific errors, such as I/O errors. :exc:`KeyError` is 32 raised for general mapping errors like specifying an incorrect key. 33 34 35.. function:: open(filename[, flag[, mode]]) 36 37 Open a dumbdbm database and return a dumbdbm object. The *filename* argument is 38 the basename of the database file (without any specific extensions). When a 39 dumbdbm database is created, files with :file:`.dat` and :file:`.dir` extensions 40 are created. 41 42 The optional *flag* argument is currently ignored; the database is always opened 43 for update, and will be created if it does not exist. 44 45 The optional *mode* argument is the Unix mode of the file, used only when the 46 database has to be created. It defaults to octal ``0666`` (and will be modified 47 by the prevailing umask). 48 49 .. versionchanged:: 2.2 50 The *mode* argument was ignored in earlier versions. 51 52 53.. seealso:: 54 55 Module :mod:`anydbm` 56 Generic interface to ``dbm``\ -style databases. 57 58 Module :mod:`dbm` 59 Similar interface to the DBM/NDBM library. 60 61 Module :mod:`gdbm` 62 Similar interface to the GNU GDBM library. 63 64 Module :mod:`shelve` 65 Persistence module which stores non-string data. 66 67 Module :mod:`whichdb` 68 Utility module used to determine the type of an existing database. 69 70 71.. _dumbdbm-objects: 72 73Dumbdbm Objects 74--------------- 75 76In addition to the methods provided by the :class:`UserDict.DictMixin` class, 77:class:`dumbdbm` objects provide the following methods. 78 79 80.. method:: dumbdbm.sync() 81 82 Synchronize the on-disk directory and data files. This method is called by the 83 :meth:`sync` method of :class:`Shelve` objects. 84