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Generic access to DBM-style databases</TITLE>
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<H1><A NAME="SECTION009700000000000000000">
7.7 <tt class=module>anydbm</tt> --
         Generic access to DBM-style databases</A>
</H1>

<P>


<P>
<tt class=module>anydbm</tt> is a generic interface to variants of the DBM
database -- <tt class=module><a href="module-dbhash.html">dbhash</a></tt><a name="l2h-1389"></a> (requires
<tt class=module><a href="module-bsddb.html">bsddb</a></tt><a name="l2h-1390"></a>),
<tt class=module><a href="module-gdbm.html">gdbm</a></tt><a name="l2h-1391"></a>, or
<tt class=module><a href="module-dbm.html">dbm</a></tt><a name="l2h-1392"></a>.  If none of these modules is
installed, the slow-but-simple implementation in module
<tt class=module><a href="module-dumbdbm.html">dumbdbm</a></tt><a name="l2h-1393"></a> will be used.

<P>
<dl><dt><b><a name="l2h-1387"><tt class=function>open</tt></a></b> (<var>filename</var><big>[</big><var>, flag</var><big>[</big><var>, mode</var><big>]</big><big>]</big>)
<dd>
Open the database file <var>filename</var> and return a corresponding object.

<P>
If the database file already exists, the <tt class=module><a href="module-whichdb.html">whichdb</a></tt> 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>
The optional <var>flag</var> argument can be
<tt>'r'</tt> to open an existing database for reading only,
<tt>'w'</tt> to open an existing database for reading and writing,
<tt>'c'</tt> to create the database if it doesn't exist, or
<tt>'n'</tt>, which will always create a new empty database.  If not
specified, the default value is <tt>'r'</tt>.

<P>
The optional <var>mode</var> argument is the Unix mode of the file, used
only when the database has to be created.  It defaults to octal
<tt>0666</tt> (and will be modified by the prevailing umask).
</dl>

<P>
<dl><dt><b><a name="l2h-1388"><tt class=exception>error</tt></a></b>
<dd>
A tuple containing the exceptions that can be raised by each of the
supported modules, with a unique exception <tt class=exception>anydbm.error</tt> as
the first item -- the latter is used when <tt class=exception>anydbm.error</tt> is
raised.
</dl>

<P>
The object returned by <tt class=function>open()</tt> supports most of the same
functionality as dictionaries; keys and their corresponding values can
be stored, retrieved, and deleted, and the <tt class=method>has_key()</tt> and
<tt class=method>keys()</tt> methods are available.  Keys and values must always be
strings.

<P>
<div class=seealso>
  <p class=heading><b>See Also:</b></p>

  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-anydbm.html">anydbm</a></tt></b>&nbsp;&nbsp;&nbsp;(Generic interface to <tt>dbm</tt>-style databases.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-dbhash.html">dbhash</a></tt></b>&nbsp;&nbsp;&nbsp;(BSD <tt>db</tt> database interface.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-dbm.html">dbm</a></tt></b>&nbsp;&nbsp;&nbsp;(Standard Unix database interface.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-dumbdbm.html">dumbdbm</a></tt></b>&nbsp;&nbsp;&nbsp;(Portable implementation of the <tt>dbm</tt> interface.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-gdbm.html">gdbm</a></tt></b>&nbsp;&nbsp;&nbsp;(GNU database interface, based on the <tt>dbm</tt> interface.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-shelve.html">shelve</a></tt></b>&nbsp;&nbsp;&nbsp;(General object persistence built on top of 
                     the Python <tt>dbm</tt> interface.)</p>
</div>
  <div class=seemodule>
<p>Module <b><tt class=module><a href="module-whichdb.html">whichdb</a></tt></b>&nbsp;&nbsp;&nbsp;(Utility module used to determine the type of an
                      existing database.)</p>
</div>
</div>

<P>
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