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<div class="section" id="module-anydbm">
<h1>12.6. <tt class="xref docutils literal"><span class="pre">anydbm</span></tt> — Generic access to DBM-style databases<a class="headerlink" href="#module-anydbm" title="Permalink to this headline">¶</a></h1>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The <tt class="xref docutils literal"><span class="pre">anydbm</span></tt> module has been renamed to <a title="(Unix) The standard "database" interface, based on ndbm." class="reference external" href="dbm.html#module-dbm"><tt class="xref docutils literal"><span class="pre">dbm</span></tt></a> in Python 3.0. The
<a class="reference external" href="../glossary.html#term-to3"><em class="xref">2to3</em></a> tool will automatically adapt imports when converting your
sources to 3.0.</p>
</div>
<p id="index-215"><tt class="xref docutils literal"><span class="pre">anydbm</span></tt> is a generic interface to variants of the DBM database —
<a title="DBM-style interface to the BSD database library." class="reference external" href="dbhash.html#module-dbhash"><tt class="xref docutils literal"><span class="pre">dbhash</span></tt></a> (requires <a title="Interface to Berkeley DB database library" class="reference external" href="bsddb.html#module-bsddb"><tt class="xref docutils literal"><span class="pre">bsddb</span></tt></a>), <a title="(Unix) GNU's reinterpretation of dbm." class="reference external" href="gdbm.html#module-gdbm"><tt class="xref docutils literal"><span class="pre">gdbm</span></tt></a>, or <a title="(Unix) The standard "database" interface, based on ndbm." class="reference external" href="dbm.html#module-dbm"><tt class="xref docutils literal"><span class="pre">dbm</span></tt></a>. If none of
these modules is installed, the slow-but-simple implementation in module
<a title="Portable implementation of the simple DBM interface." class="reference external" href="dumbdbm.html#module-dumbdbm"><tt class="xref docutils literal"><span class="pre">dumbdbm</span></tt></a> will be used.</p>
<dl class="function">
<dt id="anydbm.open">
<tt class="descclassname">anydbm.</tt><tt class="descname">open</tt><big>(</big><em>filename</em><span class="optional">[</span>, <em>flag</em><span class="optional">[</span>, <em>mode</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#anydbm.open" title="Permalink to this definition">¶</a></dt>
<dd><p>Open the database file <em>filename</em> and return a corresponding object.</p>
<p>If the database file already exists, the <a title="Guess which DBM-style module created a given database." class="reference external" href="whichdb.html#module-whichdb"><tt class="xref docutils literal"><span class="pre">whichdb</span></tt></a> 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.</p>
<p>The optional <em>flag</em> argument must be one of these values:</p>
<table border="1" class="docutils">
<colgroup>
<col width="17%" />
<col width="83%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Value</th>
<th class="head">Meaning</th>
</tr>
</thead>
<tbody valign="top">
<tr><td><tt class="docutils literal"><span class="pre">'r'</span></tt></td>
<td>Open existing database for reading only
(default)</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">'w'</span></tt></td>
<td>Open existing database for reading and
writing</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">'c'</span></tt></td>
<td>Open database for reading and writing,
creating it if it doesn’t exist</td>
</tr>
<tr><td><tt class="docutils literal"><span class="pre">'n'</span></tt></td>
<td>Always create a new, empty database, open
for reading and writing</td>
</tr>
</tbody>
</table>
<p>If not specified, the default value is <tt class="docutils literal"><span class="pre">'r'</span></tt>.</p>
<p>The optional <em>mode</em> argument is the Unix mode of the file, used only when the
database has to be created. It defaults to octal <tt class="docutils literal"><span class="pre">0666</span></tt> (and will be
modified by the prevailing umask).</p>
</dd></dl>
<dl class="exception">
<dt id="anydbm.error">
<em class="property">exception </em><tt class="descclassname">anydbm.</tt><tt class="descname">error</tt><a class="headerlink" href="#anydbm.error" title="Permalink to this definition">¶</a></dt>
<dd>A tuple containing the exceptions that can be raised by each of the supported
modules, with a unique exception also named <a title="anydbm.error" class="reference internal" href="#anydbm.error"><tt class="xref docutils literal"><span class="pre">anydbm.error</span></tt></a> as the first
item — the latter is used when <a title="anydbm.error" class="reference internal" href="#anydbm.error"><tt class="xref docutils literal"><span class="pre">anydbm.error</span></tt></a> is raised.</dd></dl>
<p>The object returned by <a title="anydbm.open" class="reference internal" href="#anydbm.open"><tt class="xref docutils literal"><span class="pre">open()</span></tt></a> supports most of the same functionality as
dictionaries; keys and their corresponding values can be stored, retrieved, and
deleted, and the <tt class="xref docutils literal"><span class="pre">has_key()</span></tt> and <tt class="xref docutils literal"><span class="pre">keys()</span></tt> methods are available. Keys
and values must always be strings.</p>
<p>The following example records some hostnames and a corresponding title, and
then prints out the contents of the database:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">anydbm</span>
<span class="c"># Open database, creating it if necessary.</span>
<span class="n">db</span> <span class="o">=</span> <span class="n">anydbm</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="s">'cache'</span><span class="p">,</span> <span class="s">'c'</span><span class="p">)</span>
<span class="c"># Record some values</span>
<span class="n">db</span><span class="p">[</span><span class="s">'www.python.org'</span><span class="p">]</span> <span class="o">=</span> <span class="s">'Python Website'</span>
<span class="n">db</span><span class="p">[</span><span class="s">'www.cnn.com'</span><span class="p">]</span> <span class="o">=</span> <span class="s">'Cable News Network'</span>
<span class="c"># Loop through contents. Other dictionary methods</span>
<span class="c"># such as .keys(), .values() also work.</span>
<span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">db</span><span class="o">.</span><span class="n">iteritems</span><span class="p">():</span>
<span class="k">print</span> <span class="n">k</span><span class="p">,</span> <span class="s">'</span><span class="se">\t</span><span class="s">'</span><span class="p">,</span> <span class="n">v</span>
<span class="c"># Storing a non-string key or value will raise an exception (most</span>
<span class="c"># likely a TypeError).</span>
<span class="n">db</span><span class="p">[</span><span class="s">'www.yahoo.com'</span><span class="p">]</span> <span class="o">=</span> <span class="mi">4</span>
<span class="c"># Close when done.</span>
<span class="n">db</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
</pre></div>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt>Module <a title="DBM-style interface to the BSD database library." class="reference external" href="dbhash.html#module-dbhash"><tt class="xref docutils literal"><span class="pre">dbhash</span></tt></a></dt>
<dd>BSD <tt class="docutils literal"><span class="pre">db</span></tt> database interface.</dd>
<dt>Module <a title="(Unix) The standard "database" interface, based on ndbm." class="reference external" href="dbm.html#module-dbm"><tt class="xref docutils literal"><span class="pre">dbm</span></tt></a></dt>
<dd>Standard Unix database interface.</dd>
<dt>Module <a title="Portable implementation of the simple DBM interface." class="reference external" href="dumbdbm.html#module-dumbdbm"><tt class="xref docutils literal"><span class="pre">dumbdbm</span></tt></a></dt>
<dd>Portable implementation of the <tt class="docutils literal"><span class="pre">dbm</span></tt> interface.</dd>
<dt>Module <a title="(Unix) GNU's reinterpretation of dbm." class="reference external" href="gdbm.html#module-gdbm"><tt class="xref docutils literal"><span class="pre">gdbm</span></tt></a></dt>
<dd>GNU database interface, based on the <tt class="docutils literal"><span class="pre">dbm</span></tt> interface.</dd>
<dt>Module <a title="Python object persistence." class="reference external" href="shelve.html#module-shelve"><tt class="xref docutils literal"><span class="pre">shelve</span></tt></a></dt>
<dd>General object persistence built on top of the Python <tt class="docutils literal"><span class="pre">dbm</span></tt> interface.</dd>
<dt>Module <a title="Guess which DBM-style module created a given database." class="reference external" href="whichdb.html#module-whichdb"><tt class="xref docutils literal"><span class="pre">whichdb</span></tt></a></dt>
<dd>Utility module used to determine the type of an existing database.</dd>
</dl>
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