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<H1><A NAME="SECTION0091400000000000000000">
7.14 <tt class="module">dumbdbm</tt> --
         Portable DBM implementation</A>
</H1>

<P>
<A NAME="module-dumbdbm"></A>

<P>
<a id='l2h-2812' xml:id='l2h-2812'></a>

<P>
<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.
</div>

<P>
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.

<P>
The module defines the following:

<P>
<dl><dt><b><span class="typelabel">exception</span>&nbsp;<tt id='l2h-2810' xml:id='l2h-2810' class="exception">error</tt></b></dt>
<dd>
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.
</dd></dl>

<P>
<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>
<dd>
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.

<P>
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.

<P>
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
                versions.</span>

</dl>

<P>
<div class="seealso">
  <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>
  <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>
  <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>
  <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>
  <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
                      existing database.
  </dl>
</div>

<P>

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	54
	55	<H1><A NAME="SECTION0091400000000000000000">
	56	7.14 <tt class="module">dumbdbm</tt> --
	57	Portable DBM implementation</A>
	58	</H1>
	59
	60	<P>
	61	<A NAME="module-dumbdbm"></A>
	62
	63	<P>
	64	<a id='l2h-2812' xml:id='l2h-2812'></a>
65
66	<P>
67	<div class="note"><b class="label">Note:</b>
68	The <tt class="module">dumbdbm</tt> module is intended as a last resort fallback for
69	the <tt class="module"><a href="module-anydbm.html">anydbm</a></tt> module when no more robust module is available.
70	The <tt class="module">dumbdbm</tt> module is not written for speed and is not nearly as
71	heavily used as the other database modules.
72	</div>
73
74	<P>
75	The <tt class="module">dumbdbm</tt> module provides a persistent dictionary-like interface
76	which is written entirely in Python. Unlike other modules such as
77	<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
78	with other persistent mappings, the keys and values must always be strings.
79
80	<P>
81	The module defines the following:
82
83	<P>
84	<dl><dt><b><span class="typelabel">exception</span> <tt id='l2h-2810' xml:id='l2h-2810' class="exception">error</tt></b></dt>
85	<dd>
86	Raised on dumbdbm-specific errors, such as I/O errors. <tt class="exception">KeyError</tt>
87	is raised for general mapping errors like specifying an incorrect key.
88	</dd></dl>
89
90	<P>
91	<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
92	<td><nobr><b><tt id='l2h-2811' xml:id='l2h-2811' class="function">open</tt></b>(</nobr></td>
93	<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>
94	<dd>
95	Open a dumbdbm database and return a dumbdbm object. The <var>filename</var>
96	argument is the basename of the database file (without any specific
97	extensions). When a dumbdbm database is created, files with <span class="file">.dat</span> and
98	<span class="file">.dir</span> extensions are created.
99
100	<P>
101	The optional <var>flag</var> argument is currently ignored; the database is
102	always opened for update, and will be created if it does not exist.
103
104	<P>
105	The optional <var>mode</var> argument is the <span class="Unix">Unix</span> mode of the file, used
106	only when the database has to be created. It defaults to octal
107	<code>0666</code> (and will be modified by the prevailing umask).
108
109	<span class="versionnote">Changed in version 2.2:
110	The <var>mode</var> argument was ignored in earlier
111	versions.</span>
112
113	</dl>
114
115	<P>
116	<div class="seealso">
117	<p class="heading">See Also:</p>
118
119	<dl compact="compact" class="seemodule">
120	<dt>Module <b><tt class="module"><a href="module-anydbm.html">anydbm</a></tt>:</b>
121	<dd>Generic interface to <code>dbm</code>-style databases.
122	</dl>
123	<dl compact="compact" class="seemodule">
124	<dt>Module <b><tt class="module"><a href="module-dbm.html">dbm</a></tt>:</b>
125	<dd>Similar interface to the DBM/NDBM library.
126	</dl>
127	<dl compact="compact" class="seemodule">
128	<dt>Module <b><tt class="module"><a href="module-gdbm.html">gdbm</a></tt>:</b>
129	<dd>Similar interface to the GNU GDBM library.
130	</dl>
131	<dl compact="compact" class="seemodule">
132	<dt>Module <b><tt class="module"><a href="module-shelve.html">shelve</a></tt>:</b>
133	<dd>Persistence module which stores non-string data.
134	</dl>
135	<dl compact="compact" class="seemodule">
136	<dt>Module <b><tt class="module"><a href="module-whichdb.html">whichdb</a></tt>:</b>
137	<dd>Utility module used to determine the type of an
138	existing database.
139	</dl>
140	</div>
141
142	<P>
143
144	<p><br /></p><hr class='online-navigation' />
145	<div class='online-navigation'>
146	<!--Table of Child-Links-->
147	<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a>
148
149	<UL CLASS="ChildLinks">
150	<LI><A href="dumbdbm-objects.html">7.14.1 Dumbdbm Objects</a>
151	</ul>
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