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  194.   <section id="module-xdrlib">

  195. <span id="xdrlib-encode-and-decode-xdr-data"></span><h1><a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR). (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code></a> — Encode and decode XDR data<a class="headerlink" href="#module-xdrlib" title="Link to this heading">¶</a></h1>

  196. <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/xdrlib.py">Lib/xdrlib.py</a></p>

  197. <div class="deprecated-removed" id="index-0">

  198. <p><span class="versionmodified">Deprecated since version 3.11, will be removed in version 3.13: </span>The <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR). (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code></a> module is deprecated

  199. (see <span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0594/#xdrlib"><strong>PEP 594</strong></a> for details).</p>

  200. </div>

  201. <hr class="docutils" />

  202. <p>The <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR). (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code></a> module supports the External Data Representation Standard as

  203. described in <span class="target" id="index-2"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1014.html"><strong>RFC 1014</strong></a>, written by Sun Microsystems, Inc. June 1987.  It

  204. supports most of the data types described in the RFC.</p>

  205. <p>The <a class="reference internal" href="#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR). (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code></a> module defines two classes, one for packing variables into XDR

  206. representation, and another for unpacking from XDR representation.  There are

  207. also two exception classes.</p>

  208. <dl class="py class">

  209. <dt class="sig sig-object py" id="xdrlib.Packer">

  210. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">xdrlib.</span></span><span class="sig-name descname"><span class="pre">Packer</span></span><a class="headerlink" href="#xdrlib.Packer" title="Link to this definition">¶</a></dt>

  211. <dd><p><a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Packer</span></code></a> is the class for packing data into XDR representation. The

  212. <a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Packer</span></code></a> class is instantiated with no arguments.</p>

  213. </dd></dl>

  214. 

  215. <dl class="py class">

  216. <dt class="sig sig-object py" id="xdrlib.Unpacker">

  217. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">xdrlib.</span></span><span class="sig-name descname"><span class="pre">Unpacker</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker" title="Link to this definition">¶</a></dt>

  218. <dd><p><code class="docutils literal notranslate"><span class="pre">Unpacker</span></code> is the complementary class which unpacks XDR data values from a

  219. string buffer.  The input buffer is given as <em>data</em>.</p>

  220. </dd></dl>

  221. 

  222. <div class="admonition seealso">

  223. <p class="admonition-title">See also</p>

  224. <dl class="simple">

  225. <dt><span class="target" id="index-3"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1014.html"><strong>RFC 1014</strong></a> - XDR: External Data Representation Standard</dt><dd><p>This RFC defined the encoding of data which was XDR at the time this module was

  226. originally written.  It has apparently been obsoleted by <span class="target" id="index-4"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1832.html"><strong>RFC 1832</strong></a>.</p>

  227. </dd>

  228. <dt><span class="target" id="index-5"></span><a class="rfc reference external" href="https://datatracker.ietf.org/doc/html/rfc1832.html"><strong>RFC 1832</strong></a> - XDR: External Data Representation Standard</dt><dd><p>Newer RFC that provides a revised definition of XDR.</p>

  229. </dd>

  230. </dl>

  231. </div>

  232. <section id="packer-objects">

  233. <span id="xdr-packer-objects"></span><h2>Packer Objects<a class="headerlink" href="#packer-objects" title="Link to this heading">¶</a></h2>

  234. <p><a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Packer</span></code></a> instances have the following methods:</p>

  235. <dl class="py method">

  236. <dt class="sig sig-object py" id="xdrlib.Packer.get_buffer">

  237. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">get_buffer</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.get_buffer" title="Link to this definition">¶</a></dt>

  238. <dd><p>Returns the current pack buffer as a string.</p>

  239. </dd></dl>

  240. 

  241. <dl class="py method">

  242. <dt class="sig sig-object py" id="xdrlib.Packer.reset">

  243. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">reset</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.reset" title="Link to this definition">¶</a></dt>

  244. <dd><p>Resets the pack buffer to the empty string.</p>

  245. </dd></dl>

  246. 

  247. <p>In general, you can pack any of the most common XDR data types by calling the

  248. appropriate <code class="docutils literal notranslate"><span class="pre">pack_type()</span></code> method.  Each method takes a single argument, the

  249. value to pack.  The following simple data type packing methods are supported:

  250. <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_uint()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_int()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_enum()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_bool()</span></code>,

  251. <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_uhyper()</span></code>, and <code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_hyper()</span></code>.</p>

  252. <dl class="py method">

  253. <dt class="sig sig-object py" id="xdrlib.Packer.pack_float">

  254. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_float</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">value</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_float" title="Link to this definition">¶</a></dt>

  255. <dd><p>Packs the single-precision floating point number <em>value</em>.</p>

  256. </dd></dl>

  257. 

  258. <dl class="py method">

  259. <dt class="sig sig-object py" id="xdrlib.Packer.pack_double">

  260. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_double</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">value</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_double" title="Link to this definition">¶</a></dt>

  261. <dd><p>Packs the double-precision floating point number <em>value</em>.</p>

  262. </dd></dl>

  263. 

  264. <p>The following methods support packing strings, bytes, and opaque data:</p>

  265. <dl class="py method">

  266. <dt class="sig sig-object py" id="xdrlib.Packer.pack_fstring">

  267. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_fstring</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">s</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_fstring" title="Link to this definition">¶</a></dt>

  268. <dd><p>Packs a fixed length string, <em>s</em>.  <em>n</em> is the length of the string but it is

  269. <em>not</em> packed into the data buffer.  The string is padded with null bytes if

  270. necessary to guaranteed 4 byte alignment.</p>

  271. </dd></dl>

  272. 

  273. <dl class="py method">

  274. <dt class="sig sig-object py" id="xdrlib.Packer.pack_fopaque">

  275. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_fopaque</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_fopaque" title="Link to this definition">¶</a></dt>

  276. <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"><code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_fstring()</span></code></a>.</p>

  277. </dd></dl>

  278. 

  279. <dl class="py method">

  280. <dt class="sig sig-object py" id="xdrlib.Packer.pack_string">

  281. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_string</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">s</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_string" title="Link to this definition">¶</a></dt>

  282. <dd><p>Packs a variable length string, <em>s</em>.  The length of the string is first packed

  283. as an unsigned integer, then the string data is packed with

  284. <a class="reference internal" href="#xdrlib.Packer.pack_fstring" title="xdrlib.Packer.pack_fstring"><code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_fstring()</span></code></a>.</p>

  285. </dd></dl>

  286. 

  287. <dl class="py method">

  288. <dt class="sig sig-object py" id="xdrlib.Packer.pack_opaque">

  289. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_opaque</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_opaque" title="Link to this definition">¶</a></dt>

  290. <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"><code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_string()</span></code></a>.</p>

  291. </dd></dl>

  292. 

  293. <dl class="py method">

  294. <dt class="sig sig-object py" id="xdrlib.Packer.pack_bytes">

  295. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_bytes</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">bytes</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_bytes" title="Link to this definition">¶</a></dt>

  296. <dd><p>Packs a variable length byte stream, similarly to <a class="reference internal" href="#xdrlib.Packer.pack_string" title="xdrlib.Packer.pack_string"><code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_string()</span></code></a>.</p>

  297. </dd></dl>

  298. 

  299. <p>The following methods support packing arrays and lists:</p>

  300. <dl class="py method">

  301. <dt class="sig sig-object py" id="xdrlib.Packer.pack_list">

  302. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_list</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">list</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">pack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_list" title="Link to this definition">¶</a></dt>

  303. <dd><p>Packs a <em>list</em> of homogeneous items.  This method is useful for lists with an

  304. indeterminate size; i.e. the size is not available until the entire list has

  305. been walked.  For each item in the list, an unsigned integer <code class="docutils literal notranslate"><span class="pre">1</span></code> is packed

  306. first, followed by the data value from the list.  <em>pack_item</em> is the function

  307. that is called to pack the individual item.  At the end of the list, an unsigned

  308. integer <code class="docutils literal notranslate"><span class="pre">0</span></code> is packed.</p>

  309. <p>For example, to pack a list of integers, the code might appear like this:</p>

  310. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">xdrlib</span>

  311. <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>

  312. <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>

  313. </pre></div>

  314. </div>

  315. </dd></dl>

  316. 

  317. <dl class="py method">

  318. <dt class="sig sig-object py" id="xdrlib.Packer.pack_farray">

  319. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_farray</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">array</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">pack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_farray" title="Link to this definition">¶</a></dt>

  320. <dd><p>Packs a fixed length list (<em>array</em>) of homogeneous items.  <em>n</em> is the length of

  321. the list; it is <em>not</em> packed into the buffer, but a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> exception

  322. is raised if <code class="docutils literal notranslate"><span class="pre">len(array)</span></code> is not equal to <em>n</em>.  As above, <em>pack_item</em> is the

  323. function used to pack each element.</p>

  324. </dd></dl>

  325. 

  326. <dl class="py method">

  327. <dt class="sig sig-object py" id="xdrlib.Packer.pack_array">

  328. <span class="sig-prename descclassname"><span class="pre">Packer.</span></span><span class="sig-name descname"><span class="pre">pack_array</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">list</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">pack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Packer.pack_array" title="Link to this definition">¶</a></dt>

  329. <dd><p>Packs a variable length <em>list</em> of homogeneous items.  First, the length of the

  330. list is packed as an unsigned integer, then each element is packed as in

  331. <a class="reference internal" href="#xdrlib.Packer.pack_farray" title="xdrlib.Packer.pack_farray"><code class="xref py py-meth docutils literal notranslate"><span class="pre">pack_farray()</span></code></a> above.</p>

  332. </dd></dl>

  333. 

  334. </section>

  335. <section id="unpacker-objects">

  336. <span id="xdr-unpacker-objects"></span><h2>Unpacker Objects<a class="headerlink" href="#unpacker-objects" title="Link to this heading">¶</a></h2>

  337. <p>The <a class="reference internal" href="#xdrlib.Unpacker" title="xdrlib.Unpacker"><code class="xref py py-class docutils literal notranslate"><span class="pre">Unpacker</span></code></a> class offers the following methods:</p>

  338. <dl class="py method">

  339. <dt class="sig sig-object py" id="xdrlib.Unpacker.reset">

  340. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">reset</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.reset" title="Link to this definition">¶</a></dt>

  341. <dd><p>Resets the string buffer with the given <em>data</em>.</p>

  342. </dd></dl>

  343. 

  344. <dl class="py method">

  345. <dt class="sig sig-object py" id="xdrlib.Unpacker.get_position">

  346. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">get_position</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.get_position" title="Link to this definition">¶</a></dt>

  347. <dd><p>Returns the current unpack position in the data buffer.</p>

  348. </dd></dl>

  349. 

  350. <dl class="py method">

  351. <dt class="sig sig-object py" id="xdrlib.Unpacker.set_position">

  352. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">set_position</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">position</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.set_position" title="Link to this definition">¶</a></dt>

  353. <dd><p>Sets the data buffer unpack position to <em>position</em>.  You should be careful about

  354. using <a class="reference internal" href="#xdrlib.Unpacker.get_position" title="xdrlib.Unpacker.get_position"><code class="xref py py-meth docutils literal notranslate"><span class="pre">get_position()</span></code></a> and <a class="reference internal" href="#xdrlib.Unpacker.set_position" title="xdrlib.Unpacker.set_position"><code class="xref py py-meth docutils literal notranslate"><span class="pre">set_position()</span></code></a>.</p>

  355. </dd></dl>

  356. 

  357. <dl class="py method">

  358. <dt class="sig sig-object py" id="xdrlib.Unpacker.get_buffer">

  359. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">get_buffer</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.get_buffer" title="Link to this definition">¶</a></dt>

  360. <dd><p>Returns the current unpack data buffer as a string.</p>

  361. </dd></dl>

  362. 

  363. <dl class="py method">

  364. <dt class="sig sig-object py" id="xdrlib.Unpacker.done">

  365. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">done</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.done" title="Link to this definition">¶</a></dt>

  366. <dd><p>Indicates unpack completion.  Raises an <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> exception if all of the

  367. data has not been unpacked.</p>

  368. </dd></dl>

  369. 

  370. <p>In addition, every data type that can be packed with a <a class="reference internal" href="#xdrlib.Packer" title="xdrlib.Packer"><code class="xref py py-class docutils literal notranslate"><span class="pre">Packer</span></code></a>, can be

  371. unpacked with an <a class="reference internal" href="#xdrlib.Unpacker" title="xdrlib.Unpacker"><code class="xref py py-class docutils literal notranslate"><span class="pre">Unpacker</span></code></a>.  Unpacking methods are of the form

  372. <code class="docutils literal notranslate"><span class="pre">unpack_type()</span></code>, and take no arguments.  They return the unpacked object.</p>

  373. <dl class="py method">

  374. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_float">

  375. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_float</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_float" title="Link to this definition">¶</a></dt>

  376. <dd><p>Unpacks a single-precision floating point number.</p>

  377. </dd></dl>

  378. 

  379. <dl class="py method">

  380. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_double">

  381. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_double</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_double" title="Link to this definition">¶</a></dt>

  382. <dd><p>Unpacks a double-precision floating point number, similarly to

  383. <a class="reference internal" href="#xdrlib.Unpacker.unpack_float" title="xdrlib.Unpacker.unpack_float"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_float()</span></code></a>.</p>

  384. </dd></dl>

  385. 

  386. <p>In addition, the following methods unpack strings, bytes, and opaque data:</p>

  387. <dl class="py method">

  388. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_fstring">

  389. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_fstring</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_fstring" title="Link to this definition">¶</a></dt>

  390. <dd><p>Unpacks and returns a fixed length string.  <em>n</em> is the number of characters

  391. expected.  Padding with null bytes to guaranteed 4 byte alignment is assumed.</p>

  392. </dd></dl>

  393. 

  394. <dl class="py method">

  395. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_fopaque">

  396. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_fopaque</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_fopaque" title="Link to this definition">¶</a></dt>

  397. <dd><p>Unpacks and returns a fixed length opaque data stream, similarly to

  398. <a class="reference internal" href="#xdrlib.Unpacker.unpack_fstring" title="xdrlib.Unpacker.unpack_fstring"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_fstring()</span></code></a>.</p>

  399. </dd></dl>

  400. 

  401. <dl class="py method">

  402. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_string">

  403. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_string</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_string" title="Link to this definition">¶</a></dt>

  404. <dd><p>Unpacks and returns a variable length string.  The length of the string is first

  405. unpacked as an unsigned integer, then the string data is unpacked with

  406. <a class="reference internal" href="#xdrlib.Unpacker.unpack_fstring" title="xdrlib.Unpacker.unpack_fstring"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_fstring()</span></code></a>.</p>

  407. </dd></dl>

  408. 

  409. <dl class="py method">

  410. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_opaque">

  411. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_opaque</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_opaque" title="Link to this definition">¶</a></dt>

  412. <dd><p>Unpacks and returns a variable length opaque data string, similarly to

  413. <a class="reference internal" href="#xdrlib.Unpacker.unpack_string" title="xdrlib.Unpacker.unpack_string"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_string()</span></code></a>.</p>

  414. </dd></dl>

  415. 

  416. <dl class="py method">

  417. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_bytes">

  418. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_bytes</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_bytes" title="Link to this definition">¶</a></dt>

  419. <dd><p>Unpacks and returns a variable length byte stream, similarly to

  420. <a class="reference internal" href="#xdrlib.Unpacker.unpack_string" title="xdrlib.Unpacker.unpack_string"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_string()</span></code></a>.</p>

  421. </dd></dl>

  422. 

  423. <p>The following methods support unpacking arrays and lists:</p>

  424. <dl class="py method">

  425. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_list">

  426. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_list</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">unpack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_list" title="Link to this definition">¶</a></dt>

  427. <dd><p>Unpacks and returns a list of homogeneous items.  The list is unpacked one

  428. element at a time by first unpacking an unsigned integer flag.  If the flag is

  429. <code class="docutils literal notranslate"><span class="pre">1</span></code>, then the item is unpacked and appended to the list.  A flag of <code class="docutils literal notranslate"><span class="pre">0</span></code>

  430. indicates the end of the list.  <em>unpack_item</em> is the function that is called to

  431. unpack the items.</p>

  432. </dd></dl>

  433. 

  434. <dl class="py method">

  435. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_farray">

  436. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_farray</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">n</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">unpack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_farray" title="Link to this definition">¶</a></dt>

  437. <dd><p>Unpacks and returns (as a list) a fixed length array of homogeneous items.  <em>n</em>

  438. is number of list elements to expect in the buffer. As above, <em>unpack_item</em> is

  439. the function used to unpack each element.</p>

  440. </dd></dl>

  441. 

  442. <dl class="py method">

  443. <dt class="sig sig-object py" id="xdrlib.Unpacker.unpack_array">

  444. <span class="sig-prename descclassname"><span class="pre">Unpacker.</span></span><span class="sig-name descname"><span class="pre">unpack_array</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">unpack_item</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#xdrlib.Unpacker.unpack_array" title="Link to this definition">¶</a></dt>

  445. <dd><p>Unpacks and returns a variable length <em>list</em> of homogeneous items. First, the

  446. length of the list is unpacked as an unsigned integer, then each element is

  447. unpacked as in <a class="reference internal" href="#xdrlib.Unpacker.unpack_farray" title="xdrlib.Unpacker.unpack_farray"><code class="xref py py-meth docutils literal notranslate"><span class="pre">unpack_farray()</span></code></a> above.</p>

  448. </dd></dl>

  449. 

  450. </section>

  451. <section id="exceptions">

  452. <span id="xdr-exceptions"></span><h2>Exceptions<a class="headerlink" href="#exceptions" title="Link to this heading">¶</a></h2>

  453. <p>Exceptions in this module are coded as class instances:</p>

  454. <dl class="py exception">

  455. <dt class="sig sig-object py" id="xdrlib.Error">

  456. <em class="property"><span class="pre">exception</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">xdrlib.</span></span><span class="sig-name descname"><span class="pre">Error</span></span><a class="headerlink" href="#xdrlib.Error" title="Link to this definition">¶</a></dt>

  457. <dd><p>The base exception class.  <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a> has a single public attribute

  458. <code class="xref py py-attr docutils literal notranslate"><span class="pre">msg</span></code> containing the description of the error.</p>

  459. </dd></dl>

  460. 

  461. <dl class="py exception">

  462. <dt class="sig sig-object py" id="xdrlib.ConversionError">

  463. <em class="property"><span class="pre">exception</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">xdrlib.</span></span><span class="sig-name descname"><span class="pre">ConversionError</span></span><a class="headerlink" href="#xdrlib.ConversionError" title="Link to this definition">¶</a></dt>

  464. <dd><p>Class derived from <a class="reference internal" href="#xdrlib.Error" title="xdrlib.Error"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Error</span></code></a>.  Contains no additional instance variables.</p>

  465. </dd></dl>

  466. 

  467. <p>Here is an example of how you would catch one of these exceptions:</p>

  468. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">xdrlib</span>

  469. <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>

  470. <span class="k">try</span><span class="p">:</span>

  471.     <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>

  472. <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>

  473.     <span class="nb">print</span><span class="p">(</span><span class="s1">&#39;packing the double failed:&#39;</span><span class="p">,</span> <span class="n">instance</span><span class="o">.</span><span class="n">msg</span><span class="p">)</span>

  474. </pre></div>

  475. </div>

  476. </section>

  477. </section>

  478. 

  479. 

  480.             <div class="clearer"></div>

  481.           </div>

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  486.   <div>

  487.     <h3><a href="../contents.html">Table of Contents</a></h3>

  488.     <ul>

  489. <li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code> — Encode and decode XDR data</a><ul>

  490. <li><a class="reference internal" href="#packer-objects">Packer Objects</a></li>

  491. <li><a class="reference internal" href="#unpacker-objects">Unpacker Objects</a></li>

  492. <li><a class="reference internal" href="#exceptions">Exceptions</a></li>

  493. </ul>

  494. </li>

  495. </ul>

  496. 

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