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<title>7.14 dumbdbm -- Portable DBM implementation
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<H1><A NAME=
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7.14 <tt class=
"module">dumbdbm
</tt> --
Portable DBM implementation
</A>
<A NAME=
"module-dumbdbm"></A>
<a id='l2h-
2812' xml:id='l2h-
2812'
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<div class=
"note"><b class=
"label">Note:
</b>
The
<tt class=
"module">dumbdbm
</tt> module is intended as a last resort fallback for
the
<tt class=
"module"><a href=
"module-anydbm.html">anydbm
</a></tt> module when no more robust module is available.
The
<tt class=
"module">dumbdbm
</tt> module is not written for speed and is not nearly as
heavily used as the other database modules.
The
<tt class=
"module">dumbdbm
</tt> module provides a persistent dictionary-like interface
which is written entirely in Python. Unlike other modules such as
<tt class=
"module"><a href=
"module-gdbm.html">gdbm
</a></tt> and
<tt class=
"module"><a href=
"module-bsddb.html">bsddb
</a></tt>, no external library is required. As
with other persistent mappings, the keys and values must always be strings.
The module defines the following:
<dl><dt><b><span class=
"typelabel">exception
</span> <tt id='l2h-
2810' xml:id='l2h-
2810'
class=
"exception">error
</tt></b></dt>
Raised on dumbdbm-specific errors, such as I/O errors.
<tt class=
"exception">KeyError
</tt>
is raised for general mapping errors like specifying an incorrect key.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
2811' xml:id='l2h-
2811'
class=
"function">open
</tt></b>(
</nobr></td>
<td><var>filename
</var><big>[
</big><var>, flag
</var><big>[
</big><var>, mode
</var><big>]
</big><var></var><big>]
</big><var></var>)
</td></tr></table></dt>
Open a dumbdbm database and return a dumbdbm object. The
<var>filename
</var>
argument is the basename of the database file (without any specific
extensions). When a dumbdbm database is created, files with
<span class=
"file">.dat
</span> and
<span class=
"file">.dir
</span> extensions are created.
The optional
<var>flag
</var> argument is currently ignored; the database is
always opened for update, and will be created if it does not exist.
The optional
<var>mode
</var> argument is the
<span class=
"Unix">Unix
</span> mode of the file, used
only when the database has to be created. It defaults to octal
<code>0666</code> (and will be modified by the prevailing umask).
<span class=
"versionnote">Changed in version
2.2:
The
<var>mode
</var> argument was ignored in earlier
<p class=
"heading">See Also:
</p>
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-anydbm.html">anydbm
</a></tt>:
</b>
<dd>Generic interface to
<code>dbm
</code>-style databases.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-dbm.html">dbm
</a></tt>:
</b>
<dd>Similar interface to the DBM/NDBM library.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-gdbm.html">gdbm
</a></tt>:
</b>
<dd>Similar interface to the GNU GDBM library.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-shelve.html">shelve
</a></tt>:
</b>
<dd>Persistence module which stores non-string data.
<dl compact=
"compact" class=
"seemodule">
<dt>Module
<b><tt class=
"module"><a href=
"module-whichdb.html">whichdb
</a></tt>:
</b>
<dd>Utility module used to determine the type of an
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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