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abc.rst.txt	11805	0644	editdlrm
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asyncio.rst.txt	2272	0644	editdlrm
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atexit.rst.txt	3669	0644	editdlrm
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dbm.rst.txt	14293	0644	editdlrm
debug.rst.txt	471	0644	editdlrm
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faulthandler.rst.txt	6136	0644	editdlrm
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fpectl.rst.txt	4180	0644	editdlrm
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ftplib.rst.txt	17552	0644	editdlrm
functional.rst.txt	365	0644	editdlrm
functions.rst.txt	71621	0644	editdlrm
functools.rst.txt	18503	0644	editdlrm
gc.rst.txt	9694	0644	editdlrm
getopt.rst.txt	6557	0644	editdlrm
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html.entities.rst.txt	1319	0644	editdlrm
html.parser.rst.txt	11275	0644	editdlrm
html.rst.txt	1304	0644	editdlrm
http.client.rst.txt	18870	0644	editdlrm
http.cookiejar.rst.txt	27832	0644	editdlrm
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keyword.rst.txt	617	0644	editdlrm
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logging.config.rst.txt	33886	0644	editdlrm
logging.handlers.rst.txt	42497	0644	editdlrm
logging.rst.txt	60479	0644	editdlrm
lzma.rst.txt	17361	0644	editdlrm
macpath.rst.txt	707	0644	editdlrm
mailbox.rst.txt	63055	0644	editdlrm
mailcap.rst.txt	3691	0644	editdlrm
markup.rst.txt	679	0644	editdlrm
marshal.rst.txt	4855	0644	editdlrm
math.rst.txt	14375	0644	editdlrm
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modulefinder.rst.txt	3240	0644	editdlrm
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msilib.rst.txt	18612	0644	editdlrm
msvcrt.rst.txt	4392	0644	editdlrm
multiprocessing.rst.txt	104494	0644	editdlrm
netdata.rst.txt	339	0644	editdlrm
netrc.rst.txt	3007	0644	editdlrm
nis.rst.txt	1993	0644	editdlrm
nntplib.rst.txt	21821	0644	editdlrm
numbers.rst.txt	8089	0644	editdlrm
numeric.rst.txt	696	0644	editdlrm
operator.rst.txt	18989	0644	editdlrm
optparse.rst.txt	76996	0644	editdlrm
os.path.rst.txt	16419	0644	editdlrm
os.rst.txt	137534	0644	editdlrm
ossaudiodev.rst.txt	17845	0644	editdlrm
othergui.rst.txt	2822	0644	editdlrm
parser.rst.txt	15148	0644	editdlrm
pathlib.rst.txt	30045	0644	editdlrm
pdb.rst.txt	19454	0644	editdlrm
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pickle.rst.txt	37440	0644	editdlrm
pickletools.rst.txt	3729	0644	editdlrm
pipes.rst.txt	2557	0644	editdlrm
pkgutil.rst.txt	8730	0644	editdlrm
platform.rst.txt	9624	0644	editdlrm
plistlib.rst.txt	7398	0644	editdlrm
poplib.rst.txt	8197	0644	editdlrm
posix.rst.txt	3694	0644	editdlrm
pprint.rst.txt	14274	0644	editdlrm
profile.rst.txt	27969	0644	editdlrm
pty.rst.txt	3123	0644	editdlrm
pwd.rst.txt	2739	0644	editdlrm
pyclbr.rst.txt	3297	0644	editdlrm
pydoc.rst.txt	4688	0644	editdlrm
pyexpat.rst.txt	28620	0644	editdlrm
python.rst.txt	475	0644	editdlrm
py_compile.rst.txt	3851	0644	editdlrm
queue.rst.txt	7268	0644	editdlrm
quopri.rst.txt	2571	0644	editdlrm
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re.rst.txt	64936	0644	editdlrm
readline.rst.txt	11943	0644	editdlrm
reprlib.rst.txt	5162	0644	editdlrm
resource.rst.txt	12291	0644	editdlrm
rlcompleter.rst.txt	2294	0644	editdlrm
runpy.rst.txt	8285	0644	editdlrm
sched.rst.txt	4842	0644	editdlrm
secrets.rst.txt	5930	0644	editdlrm
select.rst.txt	28175	0644	editdlrm
selectors.rst.txt	8925	0644	editdlrm
shelve.rst.txt	8390	0644	editdlrm
shlex.rst.txt	16441	0644	editdlrm
shutil.rst.txt	26014	0644	editdlrm
signal.rst.txt	17218	0644	editdlrm
site.rst.txt	9628	0644	editdlrm
smtpd.rst.txt	10806	0644	editdlrm
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stdtypes.rst.txt	179240	0644	editdlrm
string.rst.txt	35374	0644	editdlrm
stringprep.rst.txt	4279	0644	editdlrm
struct.rst.txt	19581	0644	editdlrm
subprocess.rst.txt	45793	0644	editdlrm
sunau.rst.txt	7390	0644	editdlrm
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symbol.rst.txt	975	0644	editdlrm
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sys.rst.txt	58273	0644	editdlrm
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telnetlib.rst.txt	7899	0644	editdlrm
tempfile.rst.txt	13857	0644	editdlrm
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__future__.rst.txt	5245	0644	editdlrm
__main__.rst.txt	904	0644	editdlrm

:mod:`dbm` --- Interfaces to Unix "databases" ============================================= .. module:: dbm :synopsis: Interfaces to various Unix "database" formats. **Source code:** :source:`Lib/dbm/__init__.py` -------------- :mod:`dbm` is a generic interface to variants of the DBM database --- :mod:`dbm.gnu` or :mod:`dbm.ndbm`. If none of these modules is installed, the slow-but-simple implementation in module :mod:`dbm.dumb` will be used. There is a `third party interface `_ to the Oracle Berkeley DB. .. exception:: error A tuple containing the exceptions that can be raised by each of the supported modules, with a unique exception also named :exc:`dbm.error` as the first item --- the latter is used when :exc:`dbm.error` is raised. .. function:: whichdb(filename) This function attempts to guess which of the several simple database modules available --- :mod:`dbm.gnu`, :mod:`dbm.ndbm` or :mod:`dbm.dumb` --- should be used to open a given file. Returns one of the following values: ``None`` if the file can't be opened because it's unreadable or doesn't exist; the empty string (``''``) if the file's format can't be guessed; or a string containing the required module name, such as ``'dbm.ndbm'`` or ``'dbm.gnu'``. .. function:: open(file, flag='r', mode=0o666) Open the database file *file* and return a corresponding object. If the database file already exists, the :func:`whichdb` function 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 can be: +---------+-------------------------------------------+ | 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 | +---------+-------------------------------------------+ The optional *mode* argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal ``0o666`` (and will be modified by the prevailing umask). The object returned by :func:`.open` supports the same basic functionality as dictionaries; keys and their corresponding values can be stored, retrieved, and deleted, and the :keyword:`in` operator and the :meth:`keys` method are available, as well as :meth:`get` and :meth:`setdefault`. .. versionchanged:: 3.2 :meth:`get` and :meth:`setdefault` are now available in all database modules. Key and values are always stored as bytes. This means that when strings are used they are implicitly converted to the default encoding before being stored. These objects also support being used in a :keyword:`with` statement, which will automatically close them when done. .. versionchanged:: 3.4 Added native support for the context management protocol to the objects returned by :func:`.open`. The following example records some hostnames and a corresponding title, and then prints out the contents of the database:: import dbm # Open database, creating it if necessary. with dbm.open('cache', 'c') as db: # Record some values db[b'hello'] = b'there' db['www.python.org'] = 'Python Website' db['www.cnn.com'] = 'Cable News Network' # Note that the keys are considered bytes now. assert db[b'www.python.org'] == b'Python Website' # Notice how the value is now in bytes. assert db['www.cnn.com'] == b'Cable News Network' # Often-used methods of the dict interface work too. print(db.get('python.org', b'not present')) # Storing a non-string key or value will raise an exception (most # likely a TypeError). db['www.yahoo.com'] = 4 # db is automatically closed when leaving the with statement. .. seealso:: Module :mod:`shelve` Persistence module which stores non-string data. The individual submodules are described in the following sections. :mod:`dbm.gnu` --- GNU's reinterpretation of dbm ------------------------------------------------ .. module:: dbm.gnu :platform: Unix :synopsis: GNU's reinterpretation of dbm. **Source code:** :source:`Lib/dbm/gnu.py` -------------- This module is quite similar to the :mod:`dbm` module, but uses the GNU library ``gdbm`` instead to provide some additional functionality. Please note that the file formats created by :mod:`dbm.gnu` and :mod:`dbm.ndbm` are incompatible. The :mod:`dbm.gnu` module provides an interface to the GNU DBM library. ``dbm.gnu.gdbm`` objects behave like mappings (dictionaries), except that keys and values are always converted to bytes before storing. Printing a ``gdbm`` object doesn't print the keys and values, and the :meth:`items` and :meth:`values` methods are not supported. .. exception:: error Raised on :mod:`dbm.gnu`-specific errors, such as I/O errors. :exc:`KeyError` is raised for general mapping errors like specifying an incorrect key. .. function:: open(filename[, flag[, mode]]) Open a ``gdbm`` database and return a :class:`gdbm` object. The *filename* argument is the name of the database file. The optional *flag* argument can be: +---------+-------------------------------------------+ | 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 | +---------+-------------------------------------------+ The following additional characters may be appended to the flag to control how the database is opened: +---------+--------------------------------------------+ | Value | Meaning | +=========+============================================+ | ``'f'`` | Open the database in fast mode. Writes | | | to the database will not be synchronized. | +---------+--------------------------------------------+ | ``'s'`` | Synchronized mode. This will cause changes | | | to the database to be immediately written | | | to the file. | +---------+--------------------------------------------+ | ``'u'`` | Do not lock database. | +---------+--------------------------------------------+ Not all flags are valid for all versions of ``gdbm``. The module constant :const:`open_flags` is a string of supported flag characters. The exception :exc:`error` is raised if an invalid flag is specified. The optional *mode* argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal ``0o666``. In addition to the dictionary-like methods, ``gdbm`` objects have the following methods: .. method:: gdbm.firstkey() It's possible to loop over every key in the database using this method and the :meth:`nextkey` method. The traversal is ordered by ``gdbm``'s internal hash values, and won't be sorted by the key values. This method returns the starting key. .. method:: gdbm.nextkey(key) Returns the key that follows *key* in the traversal. The following code prints every key in the database ``db``, without having to create a list in memory that contains them all:: k = db.firstkey() while k != None: print(k) k = db.nextkey(k) .. method:: gdbm.reorganize() If you have carried out a lot of deletions and would like to shrink the space used by the ``gdbm`` file, this routine will reorganize the database. ``gdbm`` objects will not shorten the length of a database file except by using this reorganization; otherwise, deleted file space will be kept and reused as new (key, value) pairs are added. .. method:: gdbm.sync() When the database has been opened in fast mode, this method forces any unwritten data to be written to the disk. .. method:: gdbm.close() Close the ``gdbm`` database. :mod:`dbm.ndbm` --- Interface based on ndbm ------------------------------------------- .. module:: dbm.ndbm :platform: Unix :synopsis: The standard "database" interface, based on ndbm. **Source code:** :source:`Lib/dbm/ndbm.py` -------------- The :mod:`dbm.ndbm` module provides an interface to the Unix "(n)dbm" library. Dbm objects behave like mappings (dictionaries), except that keys and values are always stored as bytes. Printing a ``dbm`` object doesn't print the keys and values, and the :meth:`items` and :meth:`values` methods are not supported. This module can be used with the "classic" ndbm interface or the GNU GDBM compatibility interface. On Unix, the :program:`configure` script will attempt to locate the appropriate header file to simplify building this module. .. exception:: error Raised on :mod:`dbm.ndbm`-specific errors, such as I/O errors. :exc:`KeyError` is raised for general mapping errors like specifying an incorrect key. .. data:: library Name of the ``ndbm`` implementation library used. .. function:: open(filename[, flag[, mode]]) Open a dbm database and return a ``ndbm`` object. The *filename* argument is the name of the database file (without the :file:`.dir` or :file:`.pag` extensions). 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 | +---------+-------------------------------------------+ The optional *mode* argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal ``0o666`` (and will be modified by the prevailing umask). In addition to the dictionary-like methods, ``ndbm`` objects provide the following method: .. method:: ndbm.close() Close the ``ndbm`` database. :mod:`dbm.dumb` --- Portable DBM implementation ----------------------------------------------- .. module:: dbm.dumb :synopsis: Portable implementation of the simple DBM interface. **Source code:** :source:`Lib/dbm/dumb.py` .. index:: single: databases .. note:: The :mod:`dbm.dumb` module is intended as a last resort fallback for the :mod:`dbm` module when a more robust module is not available. The :mod:`dbm.dumb` module is not written for speed and is not nearly as heavily used as the other database modules. -------------- The :mod:`dbm.dumb` module provides a persistent dictionary-like interface which is written entirely in Python. Unlike other modules such as :mod:`dbm.gnu` no external library is required. As with other persistent mappings, the keys and values are always stored as bytes. The module defines the following: .. exception:: error Raised on :mod:`dbm.dumb`-specific errors, such as I/O errors. :exc:`KeyError` is raised for general mapping errors like specifying an incorrect key. .. function:: open(filename[, flag[, mode]]) Open a ``dumbdbm`` database and return a dumbdbm object. The *filename* argument is the basename of the database file (without any specific extensions). When a dumbdbm database is created, files with :file:`.dat` and :file:`.dir` extensions are created. The optional *flag* argument supports only the semantics of ``'c'`` and ``'n'`` values. Other values will default to database being always opened for update, and will be created if it does not exist. The optional *mode* argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal ``0o666`` (and will be modified by the prevailing umask). .. versionchanged:: 3.5 :func:`.open` always creates a new database when the flag has the value ``'n'``. .. deprecated-removed:: 3.6 3.8 Creating database in ``'r'`` and ``'w'`` modes. Modifying database in ``'r'`` mode. In addition to the methods provided by the :class:`collections.abc.MutableMapping` class, :class:`dumbdbm` objects provide the following methods: .. method:: dumbdbm.sync() Synchronize the on-disk directory and data files. This method is called by the :meth:`Shelve.sync` method. .. method:: dumbdbm.close() Close the ``dumbdbm`` database.