mirror of https://github.com/python/cpython
115 lines
3.9 KiB
ReStructuredText
115 lines
3.9 KiB
ReStructuredText
: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()
|
|
|
|
|
|
.. 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.
|
|
|