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<H1><A NAME="SECTION0010500000000000000000">
8.5 <tt class="module">dl</tt> --
Call C functions in shared objects</A>
</H1>
<p class='availability'>Availability: <span
class='platform'>Unix</span>.</p>
<P>
The <tt class="module">dl</tt> module defines an interface to the
<tt class="cfunction">dlopen()</tt> function, which is the most common interface on
Unix platforms for handling dynamically linked libraries. It allows
the program to call arbitrary functions in such a library.
<P>
<b>Note:</b> This module will not work unless
<dl><dd><pre class="verbatim">
sizeof(int) == sizeof(long) == sizeof(char *)
</pre></dl>
If this is not the case, <tt class="exception">SystemError</tt> will be raised on
import.
<P>
The <tt class="module">dl</tt> module defines the following function:
<P>
<dl><dt><b><a name='l2h-1829'><tt class='function'>open</tt></a></b> (<var>name</var><big>[</big><var>, mode<code> = RTLD_LAZY</code></var><big>]</big>)
<dd>
Open a shared object file, and return a handle. Mode
signifies late binding (<tt class="constant">RTLD_LAZY</tt>) or immediate binding
(<tt class="constant">RTLD_NOW</tt>). Default is <tt class="constant">RTLD_LAZY</tt>. Note that some
systems do not support <tt class="constant">RTLD_NOW</tt>.
<P>
Return value is a dlobject.
</dl>
<P>
The <tt class="module">dl</tt> module defines the following constants:
<P>
<dl><dt><b><a name='l2h-1830'><tt>RTLD_LAZY</tt></a></b>
<dd>
Useful as an argument to <tt class="function">open()</tt>.
</dl>
<P>
<dl><dt><b><a name='l2h-1831'><tt>RTLD_NOW</tt></a></b>
<dd>
Useful as an argument to <tt class="function">open()</tt>. Note that on systems
which do not support immediate binding, this constant will not appear
in the module. For maximum portability, use <tt class="function">hasattr()</tt> to
determine if the system supports immediate binding.
</dl>
<P>
The <tt class="module">dl</tt> module defines the following exception:
<P>
<dl><dt><b><a name='l2h-1832'><tt class='exception'>error</tt></a></b>
<dd>
Exception raised when an error has occurred inside the dynamic loading
and linking routines.
</dl>
<P>
Example:
<P>
<dl><dd><pre class="verbatim">
>>> import dl, time
>>> a=dl.open('/lib/libc.so.6')
>>> a.call('time'), time.time()
(929723914, 929723914.498)
</pre></dl>
<P>
This example was tried on a Debian GNU/Linux system, and is a good
example of the fact that using this module is usually a bad alternative.
<P>
<p><hr>
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<LI><A NAME="tex2html3335"
href="dl-objects.html" tppabs="http://www.python.org/doc/current/lib/dl-objects.html">8.5.1 Dl Objects </A>
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