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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>13.5. xdrlib — Encode and decode XDR data — Python 2.7.5 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.7.5', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 2.7.5 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python 2.7.5 documentation" href="../index.html" /> <link rel="up" title="13. 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File Formats</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-xdrlib"> <span id="xdrlib-encode-and-decode-xdr-data"></span><h1>13.5. <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR)."><tt class="xref py py-mod docutils literal"><span class="pre">xdrlib</span></tt></a> — Encode and decode XDR data<a class="headerlink" href="#module-xdrlib" title="Permalink to this headline">¶</a></h1> <p id="index-0"><strong>Source code:</strong> <a class="reference external" href="http://hg.python.org/cpython/file/2.7/Lib/xdrlib.py">Lib/xdrlib.py</a></p> <hr class="docutils" /> <p>The <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR)."><tt class="xref py py-mod docutils literal"><span class="pre">xdrlib</span></tt></a> module supports the External Data Representation Standard as described in <span class="target" id="index-1"></span><a class="rfc reference external" href="http://tools.ietf.org/html/rfc1014.html"><strong>RFC 1014</strong></a>, written by Sun Microsystems, Inc. June 1987. It supports most of the data types described in the RFC.</p> <p>The <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR)."><tt class="xref py py-mod docutils literal"><span class="pre">xdrlib</span></tt></a> module defines two classes, one for packing variables into XDR representation, and another for unpacking from XDR representation. There are also two exception classes.</p> <dl class="class"> <dt id="xdrlib.Packer"> <em class="property">class </em><tt class="descclassname">xdrlib.</tt><tt class="descname">Packer</tt><a class="headerlink" href="#xdrlib.Packer" title="Permalink to this definition">¶</a></dt> <dd><p><a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><tt class="xref py py-class docutils literal"><span class="pre">Packer</span></tt></a> is the class for packing data into XDR representation. The <a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><tt class="xref py py-class docutils literal"><span class="pre">Packer</span></tt></a> class is instantiated with no arguments.</p> </dd></dl> <dl class="class"> <dt id="xdrlib.Unpacker"> <em class="property">class </em><tt class="descclassname">xdrlib.</tt><tt class="descname">Unpacker</tt><big>(</big><em>data</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker" title="Permalink to this definition">¶</a></dt> <dd><p><tt class="docutils literal"><span class="pre">Unpacker</span></tt> is the complementary class which unpacks XDR data values from a string buffer. The input buffer is given as <em>data</em>.</p> </dd></dl> <div class="admonition-see-also admonition seealso"> <p class="first admonition-title">See also</p> <dl class="last docutils"> <dt><span class="target" id="index-2"></span><a class="rfc reference external" href="http://tools.ietf.org/html/rfc1014.html"><strong>RFC 1014</strong></a> - XDR: External Data Representation Standard</dt> <dd>This RFC defined the encoding of data which was XDR at the time this module was originally written. It has apparently been obsoleted by <span class="target" id="index-3"></span><a class="rfc reference external" href="http://tools.ietf.org/html/rfc1832.html"><strong>RFC 1832</strong></a>.</dd> <dt><span class="target" id="index-4"></span><a class="rfc reference external" href="http://tools.ietf.org/html/rfc1832.html"><strong>RFC 1832</strong></a> - XDR: External Data Representation Standard</dt> <dd>Newer RFC that provides a revised definition of XDR.</dd> </dl> </div> <div class="section" id="packer-objects"> <span id="xdr-packer-objects"></span><h2>13.5.1. Packer Objects<a class="headerlink" href="#packer-objects" title="Permalink to this headline">¶</a></h2> <p><a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><tt class="xref py py-class docutils literal"><span class="pre">Packer</span></tt></a> instances have the following methods:</p> <dl class="method"> <dt id="xdrlib.Packer.get_buffer"> <tt class="descclassname">Packer.</tt><tt class="descname">get_buffer</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Packer.get_buffer" title="Permalink to this definition">¶</a></dt> <dd><p>Returns the current pack buffer as a string.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.reset"> <tt class="descclassname">Packer.</tt><tt class="descname">reset</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Packer.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Resets the pack buffer to the empty string.</p> </dd></dl> <p>In general, you can pack any of the most common XDR data types by calling the appropriate <tt class="docutils literal"><span class="pre">pack_type()</span></tt> method. Each method takes a single argument, the value to pack. The following simple data type packing methods are supported: <tt class="xref py py-meth docutils literal"><span class="pre">pack_uint()</span></tt>, <tt class="xref py py-meth docutils literal"><span class="pre">pack_int()</span></tt>, <tt class="xref py py-meth docutils literal"><span class="pre">pack_enum()</span></tt>, <tt class="xref py py-meth docutils literal"><span class="pre">pack_bool()</span></tt>, <tt class="xref py py-meth docutils literal"><span class="pre">pack_uhyper()</span></tt>, and <tt class="xref py py-meth docutils literal"><span class="pre">pack_hyper()</span></tt>.</p> <dl class="method"> <dt id="xdrlib.Packer.pack_float"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_float</tt><big>(</big><em>value</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_float" title="Permalink to this definition">¶</a></dt> <dd><p>Packs the single-precision floating point number <em>value</em>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_double"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_double</tt><big>(</big><em>value</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_double" title="Permalink to this definition">¶</a></dt> <dd><p>Packs the double-precision floating point number <em>value</em>.</p> </dd></dl> <p>The following methods support packing strings, bytes, and opaque data:</p> <dl class="method"> <dt id="xdrlib.Packer.pack_fstring"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_fstring</tt><big>(</big><em>n</em>, <em>s</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_fstring" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a fixed length string, <em>s</em>. <em>n</em> is the length of the string but it is <em>not</em> packed into the data buffer. The string is padded with null bytes if necessary to guaranteed 4 byte alignment.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_fopaque"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_fopaque</tt><big>(</big><em>n</em>, <em>data</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_fopaque" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a fixed length opaque data stream, similarly to <a class="reference internal" href="#xdrlib.Packer.pack_fstring" title="xdrlib.Packer.pack_fstring"><tt class="xref py py-meth docutils literal"><span class="pre">pack_fstring()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_string"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_string</tt><big>(</big><em>s</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_string" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a variable length string, <em>s</em>. The length of the string is first packed as an unsigned integer, then the string data is packed with <a class="reference internal" href="#xdrlib.Packer.pack_fstring" title="xdrlib.Packer.pack_fstring"><tt class="xref py py-meth docutils literal"><span class="pre">pack_fstring()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_opaque"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_opaque</tt><big>(</big><em>data</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_opaque" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a variable length opaque data string, similarly to <a class="reference internal" href="#xdrlib.Packer.pack_string" title="xdrlib.Packer.pack_string"><tt class="xref py py-meth docutils literal"><span class="pre">pack_string()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_bytes"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_bytes</tt><big>(</big><em>bytes</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_bytes" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a variable length byte stream, similarly to <a class="reference internal" href="#xdrlib.Packer.pack_string" title="xdrlib.Packer.pack_string"><tt class="xref py py-meth docutils literal"><span class="pre">pack_string()</span></tt></a>.</p> </dd></dl> <p>The following methods support packing arrays and lists:</p> <dl class="method"> <dt id="xdrlib.Packer.pack_list"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_list</tt><big>(</big><em>list</em>, <em>pack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_list" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a <em>list</em> of homogeneous items. This method is useful for lists with an indeterminate size; i.e. the size is not available until the entire list has been walked. For each item in the list, an unsigned integer <tt class="docutils literal"><span class="pre">1</span></tt> is packed first, followed by the data value from the list. <em>pack_item</em> is the function that is called to pack the individual item. At the end of the list, an unsigned integer <tt class="docutils literal"><span class="pre">0</span></tt> is packed.</p> <p>For example, to pack a list of integers, the code might appear like this:</p> <div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">xdrlib</span> <span class="n">p</span> <span class="o">=</span> <span class="n">xdrlib</span><span class="o">.</span><span class="n">Packer</span><span class="p">()</span> <span class="n">p</span><span class="o">.</span><span class="n">pack_list</span><span class="p">([</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">],</span> <span class="n">p</span><span class="o">.</span><span class="n">pack_int</span><span class="p">)</span> </pre></div> </div> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_farray"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_farray</tt><big>(</big><em>n</em>, <em>array</em>, <em>pack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_farray" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a fixed length list (<em>array</em>) of homogeneous items. <em>n</em> is the length of the list; it is <em>not</em> packed into the buffer, but a <a class="reference internal" href="exceptions.html#exceptions.ValueError" title="exceptions.ValueError"><tt class="xref py py-exc docutils literal"><span class="pre">ValueError</span></tt></a> exception is raised if <tt class="docutils literal"><span class="pre">len(array)</span></tt> is not equal to <em>n</em>. As above, <em>pack_item</em> is the function used to pack each element.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Packer.pack_array"> <tt class="descclassname">Packer.</tt><tt class="descname">pack_array</tt><big>(</big><em>list</em>, <em>pack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Packer.pack_array" title="Permalink to this definition">¶</a></dt> <dd><p>Packs a variable length <em>list</em> of homogeneous items. First, the length of the list is packed as an unsigned integer, then each element is packed as in <a class="reference internal" href="#xdrlib.Packer.pack_farray" title="xdrlib.Packer.pack_farray"><tt class="xref py py-meth docutils literal"><span class="pre">pack_farray()</span></tt></a> above.</p> </dd></dl> </div> <div class="section" id="unpacker-objects"> <span id="xdr-unpacker-objects"></span><h2>13.5.2. Unpacker Objects<a class="headerlink" href="#unpacker-objects" title="Permalink to this headline">¶</a></h2> <p>The <a class="reference internal" href="#xdrlib.Unpacker" title="xdrlib.Unpacker"><tt class="xref py py-class docutils literal"><span class="pre">Unpacker</span></tt></a> class offers the following methods:</p> <dl class="method"> <dt id="xdrlib.Unpacker.reset"> <tt class="descclassname">Unpacker.</tt><tt class="descname">reset</tt><big>(</big><em>data</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Resets the string buffer with the given <em>data</em>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.get_position"> <tt class="descclassname">Unpacker.</tt><tt class="descname">get_position</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.get_position" title="Permalink to this definition">¶</a></dt> <dd><p>Returns the current unpack position in the data buffer.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.set_position"> <tt class="descclassname">Unpacker.</tt><tt class="descname">set_position</tt><big>(</big><em>position</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.set_position" title="Permalink to this definition">¶</a></dt> <dd><p>Sets the data buffer unpack position to <em>position</em>. You should be careful about using <a class="reference internal" href="#xdrlib.Unpacker.get_position" title="xdrlib.Unpacker.get_position"><tt class="xref py py-meth docutils literal"><span class="pre">get_position()</span></tt></a> and <a class="reference internal" href="#xdrlib.Unpacker.set_position" title="xdrlib.Unpacker.set_position"><tt class="xref py py-meth docutils literal"><span class="pre">set_position()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.get_buffer"> <tt class="descclassname">Unpacker.</tt><tt class="descname">get_buffer</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.get_buffer" title="Permalink to this definition">¶</a></dt> <dd><p>Returns the current unpack data buffer as a string.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.done"> <tt class="descclassname">Unpacker.</tt><tt class="descname">done</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.done" title="Permalink to this definition">¶</a></dt> <dd><p>Indicates unpack completion. Raises an <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><tt class="xref py py-exc docutils literal"><span class="pre">Error</span></tt></a> exception if all of the data has not been unpacked.</p> </dd></dl> <p>In addition, every data type that can be packed with a <a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><tt class="xref py py-class docutils literal"><span class="pre">Packer</span></tt></a>, can be unpacked with an <a class="reference internal" href="#xdrlib.Unpacker" title="xdrlib.Unpacker"><tt class="xref py py-class docutils literal"><span class="pre">Unpacker</span></tt></a>. Unpacking methods are of the form <tt class="docutils literal"><span class="pre">unpack_type()</span></tt>, and take no arguments. They return the unpacked object.</p> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_float"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_float</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_float" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks a single-precision floating point number.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_double"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_double</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_double" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks a double-precision floating point number, similarly to <a class="reference internal" href="#xdrlib.Unpacker.unpack_float" title="xdrlib.Unpacker.unpack_float"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_float()</span></tt></a>.</p> </dd></dl> <p>In addition, the following methods unpack strings, bytes, and opaque data:</p> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_fstring"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_fstring</tt><big>(</big><em>n</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_fstring" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a fixed length string. <em>n</em> is the number of characters expected. Padding with null bytes to guaranteed 4 byte alignment is assumed.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_fopaque"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_fopaque</tt><big>(</big><em>n</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_fopaque" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a fixed length opaque data stream, similarly to <a class="reference internal" href="#xdrlib.Unpacker.unpack_fstring" title="xdrlib.Unpacker.unpack_fstring"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_fstring()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_string"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_string</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_string" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a variable length string. The length of the string is first unpacked as an unsigned integer, then the string data is unpacked with <a class="reference internal" href="#xdrlib.Unpacker.unpack_fstring" title="xdrlib.Unpacker.unpack_fstring"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_fstring()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_opaque"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_opaque</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_opaque" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a variable length opaque data string, similarly to <a class="reference internal" href="#xdrlib.Unpacker.unpack_string" title="xdrlib.Unpacker.unpack_string"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_string()</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_bytes"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_bytes</tt><big>(</big><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_bytes" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a variable length byte stream, similarly to <a class="reference internal" href="#xdrlib.Unpacker.unpack_string" title="xdrlib.Unpacker.unpack_string"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_string()</span></tt></a>.</p> </dd></dl> <p>The following methods support unpacking arrays and lists:</p> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_list"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_list</tt><big>(</big><em>unpack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_list" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a list of homogeneous items. The list is unpacked one element at a time by first unpacking an unsigned integer flag. If the flag is <tt class="docutils literal"><span class="pre">1</span></tt>, then the item is unpacked and appended to the list. A flag of <tt class="docutils literal"><span class="pre">0</span></tt> indicates the end of the list. <em>unpack_item</em> is the function that is called to unpack the items.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_farray"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_farray</tt><big>(</big><em>n</em>, <em>unpack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_farray" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns (as a list) a fixed length array of homogeneous items. <em>n</em> is number of list elements to expect in the buffer. As above, <em>unpack_item</em> is the function used to unpack each element.</p> </dd></dl> <dl class="method"> <dt id="xdrlib.Unpacker.unpack_array"> <tt class="descclassname">Unpacker.</tt><tt class="descname">unpack_array</tt><big>(</big><em>unpack_item</em><big>)</big><a class="headerlink" href="#xdrlib.Unpacker.unpack_array" title="Permalink to this definition">¶</a></dt> <dd><p>Unpacks and returns a variable length <em>list</em> of homogeneous items. First, the length of the list is unpacked as an unsigned integer, then each element is unpacked as in <a class="reference internal" href="#xdrlib.Unpacker.unpack_farray" title="xdrlib.Unpacker.unpack_farray"><tt class="xref py py-meth docutils literal"><span class="pre">unpack_farray()</span></tt></a> above.</p> </dd></dl> </div> <div class="section" id="exceptions"> <span id="xdr-exceptions"></span><h2>13.5.3. Exceptions<a class="headerlink" href="#exceptions" title="Permalink to this headline">¶</a></h2> <p>Exceptions in this module are coded as class instances:</p> <dl class="exception"> <dt id="xdrlib.Error"> <em class="property">exception </em><tt class="descclassname">xdrlib.</tt><tt class="descname">Error</tt><a class="headerlink" href="#xdrlib.Error" title="Permalink to this definition">¶</a></dt> <dd><p>The base exception class. <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><tt class="xref py py-exc docutils literal"><span class="pre">Error</span></tt></a> has a single public attribute <tt class="xref py py-attr docutils literal"><span class="pre">msg</span></tt> containing the description of the error.</p> </dd></dl> <dl class="exception"> <dt id="xdrlib.ConversionError"> <em class="property">exception </em><tt class="descclassname">xdrlib.</tt><tt class="descname">ConversionError</tt><a class="headerlink" href="#xdrlib.ConversionError" title="Permalink to this definition">¶</a></dt> <dd><p>Class derived from <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><tt class="xref py py-exc docutils literal"><span class="pre">Error</span></tt></a>. Contains no additional instance variables.</p> </dd></dl> <p>Here is an example of how you would catch one of these exceptions:</p> <div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">xdrlib</span> <span class="n">p</span> <span class="o">=</span> <span class="n">xdrlib</span><span class="o">.</span><span class="n">Packer</span><span class="p">()</span> <span class="k">try</span><span class="p">:</span> <span class="n">p</span><span class="o">.</span><span class="n">pack_double</span><span class="p">(</span><span class="mf">8.01</span><span class="p">)</span> <span class="k">except</span> <span class="n">xdrlib</span><span class="o">.</span><span class="n">ConversionError</span> <span class="k">as</span> <span class="n">instance</span><span class="p">:</span> <span class="k">print</span> <span class="s">'packing the double failed:'</span><span class="p">,</span> <span class="n">instance</span><span class="o">.</span><span class="n">msg</span> </pre></div> </div> </div> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">13.5. <tt class="docutils literal"><span class="pre">xdrlib</span></tt> — Encode and decode XDR data</a><ul> <li><a class="reference internal" href="#packer-objects">13.5.1. Packer Objects</a></li> <li><a class="reference internal" href="#unpacker-objects">13.5.2. Unpacker Objects</a></li> <li><a class="reference internal" href="#exceptions">13.5.3. Exceptions</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="netrc.html" title="previous chapter">13.4. <tt class="docutils literal"><span class="pre">netrc</span></tt> — netrc file processing</a></p> <h4>Next topic</h4> <p class="topless"><a href="plistlib.html" title="next chapter">13.6. <tt class="docutils literal"><span class="pre">plistlib</span></tt> — Generate and parse Mac OS X <tt class="docutils literal"><span class="pre">.plist</span></tt> files</a></p> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/library/xdrlib.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="plistlib.html" title="13.6. plistlib — Generate and parse Mac OS X .plist files" >next</a> |</li> <li class="right" > <a href="netrc.html" title="13.4. netrc — netrc file processing" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.5 documentation</a> » </li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="fileformats.html" >13. 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