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<div class="section" id="module-anydbm">
<span id="anydbm-generic-access-to-dbm-style-databases"></span><h1>11.6. <a class="reference internal" href="#module-anydbm" title="anydbm: Generic interface to DBM-style database modules."><code class="xref py py-mod docutils literal notranslate"><span class="pre">anydbm</span></code></a> — 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="admonition-title">Note</p>
<p>The <a class="reference internal" href="#module-anydbm" title="anydbm: Generic interface to DBM-style database modules."><code class="xref py py-mod docutils literal notranslate"><span class="pre">anydbm</span></code></a> module has been renamed to <a class="reference internal" href="dbm.html#module-dbm" title="dbm: The standard "database" interface, based on ndbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code></a> in Python 3. The
<a class="reference internal" href="../glossary.html#term-2to3"><span class="xref std std-term">2to3</span></a> tool will automatically adapt imports when converting your
sources to Python 3.</p>
</div>
<p id="index-0"><a class="reference internal" href="#module-anydbm" title="anydbm: Generic interface to DBM-style database modules."><code class="xref py py-mod docutils literal notranslate"><span class="pre">anydbm</span></code></a> is a generic interface to variants of the DBM database —
<a class="reference internal" href="dbhash.html#module-dbhash" title="dbhash: DBM-style interface to the BSD database library."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbhash</span></code></a> (requires <a class="reference internal" href="bsddb.html#module-bsddb" title="bsddb: Interface to Berkeley DB database library"><code class="xref py py-mod docutils literal notranslate"><span class="pre">bsddb</span></code></a>), <a class="reference internal" href="gdbm.html#module-gdbm" title="gdbm: GNU's reinterpretation of dbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gdbm</span></code></a>, or <a class="reference internal" href="dbm.html#module-dbm" title="dbm: The standard "database" interface, based on ndbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code></a>. If none of
these modules is installed, the slow-but-simple implementation in module
<a class="reference internal" href="dumbdbm.html#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> will be used.</p>
<dl class="function">
<dt id="anydbm.open">
<code class="descclassname">anydbm.</code><code class="descname">open</code><span class="sig-paren">(</span><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><span class="sig-paren">)</span><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 class="reference internal" href="whichdb.html#module-whichdb" title="whichdb: Guess which DBM-style module created a given database."><code class="xref py py-mod docutils literal notranslate"><span class="pre">whichdb</span></code></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 class="docutils align-center">
<colgroup>
<col style="width: 17%" />
<col style="width: 83%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Value</p></th>
<th class="head"><p>Meaning</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code></p></td>
<td><p>Open existing database for reading only
(default)</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code></p></td>
<td><p>Open existing database for reading and
writing</p></td>
</tr>
<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'c'</span></code></p></td>
<td><p>Open database for reading and writing,
creating it if it doesn’t exist</p></td>
</tr>
<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'n'</span></code></p></td>
<td><p>Always create a new, empty database, open
for reading and writing</p></td>
</tr>
</tbody>
</table>
<p>If not specified, the default value is <code class="docutils literal notranslate"><span class="pre">'r'</span></code>.</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 <code class="docutils literal notranslate"><span class="pre">0666</span></code> (and will be
modified by the prevailing umask).</p>
</dd></dl>
<dl class="exception">
<dt id="anydbm.error">
<em class="property">exception </em><code class="descclassname">anydbm.</code><code class="descname">error</code><a class="headerlink" href="#anydbm.error" title="Permalink to this definition">¶</a></dt>
<dd><p>A tuple containing the exceptions that can be raised by each of the supported
modules, with a unique exception also named <a class="reference internal" href="#anydbm.error" title="anydbm.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">anydbm.error</span></code></a> as the first
item — the latter is used when <a class="reference internal" href="#anydbm.error" title="anydbm.error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">anydbm.error</span></code></a> is raised.</p>
</dd></dl>
<p>The object returned by <a class="reference internal" href="#anydbm.open" title="anydbm.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> supports most of the same functionality as
dictionaries; keys and their corresponding values can be stored, retrieved, and
deleted, and the <code class="xref py py-meth docutils literal notranslate"><span class="pre">has_key()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">keys()</span></code> 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-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">anydbm</span>
<span class="c1"># 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="s1">'cache'</span><span class="p">,</span> <span class="s1">'c'</span><span class="p">)</span>
<span class="c1"># Record some values</span>
<span class="n">db</span><span class="p">[</span><span class="s1">'www.python.org'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'Python Website'</span>
<span class="n">db</span><span class="p">[</span><span class="s1">'www.cnn.com'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'Cable News Network'</span>
<span class="c1"># Loop through contents. Other dictionary methods</span>
<span class="c1"># 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="nb">print</span> <span class="n">k</span><span class="p">,</span> <span class="s1">'</span><span class="se">\t</span><span class="s1">'</span><span class="p">,</span> <span class="n">v</span>
<span class="c1"># Storing a non-string key or value will raise an exception (most</span>
<span class="c1"># likely a TypeError).</span>
<span class="n">db</span><span class="p">[</span><span class="s1">'www.yahoo.com'</span><span class="p">]</span> <span class="o">=</span> <span class="mi">4</span>
<span class="c1"># 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>
<p>In addition to the dictionary-like methods, <code class="docutils literal notranslate"><span class="pre">anydbm</span></code> objects
provide the following method:</p>
<dl class="function">
<dt id="anydbm.close">
<code class="descclassname">anydbm.</code><code class="descname">close</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#anydbm.close" title="Permalink to this definition">¶</a></dt>
<dd><p>Close the <code class="docutils literal notranslate"><span class="pre">anydbm</span></code> database.</p>
</dd></dl>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<dl class="simple">
<dt>Module <a class="reference internal" href="dbhash.html#module-dbhash" title="dbhash: DBM-style interface to the BSD database library."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbhash</span></code></a></dt><dd><p>BSD <code class="docutils literal notranslate"><span class="pre">db</span></code> database interface.</p>
</dd>
<dt>Module <a class="reference internal" href="dbm.html#module-dbm" title="dbm: The standard "database" interface, based on ndbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code></a></dt><dd><p>Standard Unix database interface.</p>
</dd>
<dt>Module <a class="reference internal" href="dumbdbm.html#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a></dt><dd><p>Portable implementation of the <code class="docutils literal notranslate"><span class="pre">dbm</span></code> interface.</p>
</dd>
<dt>Module <a class="reference internal" href="gdbm.html#module-gdbm" title="gdbm: GNU's reinterpretation of dbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gdbm</span></code></a></dt><dd><p>GNU database interface, based on the <code class="docutils literal notranslate"><span class="pre">dbm</span></code> interface.</p>
</dd>
<dt>Module <a class="reference internal" href="shelve.html#module-shelve" title="shelve: Python object persistence."><code class="xref py py-mod docutils literal notranslate"><span class="pre">shelve</span></code></a></dt><dd><p>General object persistence built on top of the Python <code class="docutils literal notranslate"><span class="pre">dbm</span></code> interface.</p>
</dd>
<dt>Module <a class="reference internal" href="whichdb.html#module-whichdb" title="whichdb: Guess which DBM-style module created a given database."><code class="xref py py-mod docutils literal notranslate"><span class="pre">whichdb</span></code></a></dt><dd><p>Utility module used to determine the type of an existing database.</p>
</dd>
</dl>
</div>
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