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Editing: codecs.html
<!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="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>7.2. codecs — Codec registry and base classes — Python 3.6.7 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></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 3.6.7 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="8. Data Types" href="datatypes.html" /> <link rel="prev" title="7.1. struct — Interpret bytes as packed binary data" href="struct.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/codecs.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="datatypes.html" title="8. Data Types" accesskey="N">next</a> |</li> <li class="right" > <a href="struct.html" title="7.1. struct — Interpret bytes as packed binary data" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.6.7 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="binary.html" accesskey="U">7. Binary Data Services</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" 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> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-codecs"> <span id="codecs-codec-registry-and-base-classes"></span><h1>7.2. <a class="reference internal" href="#module-codecs" title="codecs: Encode and decode data and streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">codecs</span></code></a> — Codec registry and base classes<a class="headerlink" href="#module-codecs" title="Permalink to this headline">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.6/Lib/codecs.py">Lib/codecs.py</a></p> <hr class="docutils" id="index-0" /> <p>This module defines base classes for standard Python codecs (encoders and decoders) and provides access to the internal Python codec registry, which manages the codec and error handling lookup process. Most standard codecs are <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a>, which encode text to bytes, but there are also codecs provided that encode text to text, and bytes to bytes. Custom codecs may encode and decode between arbitrary types, but some module features are restricted to use specifically with <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a>, or with codecs that encode to <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>.</p> <p>The module defines the following functions for encoding and decoding with any codec:</p> <dl class="function"> <dt id="codecs.encode"> <code class="descclassname">codecs.</code><code class="descname">encode</code><span class="sig-paren">(</span><em>obj</em>, <em>encoding='utf-8'</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.encode" title="Permalink to this definition">¶</a></dt> <dd><p>Encodes <em>obj</em> using the codec registered for <em>encoding</em>.</p> <p><em>Errors</em> may be given to set the desired error handling scheme. The default error handler is <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> meaning that encoding errors raise <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> (or a more codec specific subclass, such as <a class="reference internal" href="exceptions.html#UnicodeEncodeError" title="UnicodeEncodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeEncodeError</span></code></a>). Refer to <a class="reference internal" href="#codec-base-classes"><span class="std std-ref">Codec Base Classes</span></a> for more information on codec error handling.</p> </dd></dl> <dl class="function"> <dt id="codecs.decode"> <code class="descclassname">codecs.</code><code class="descname">decode</code><span class="sig-paren">(</span><em>obj</em>, <em>encoding='utf-8'</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.decode" title="Permalink to this definition">¶</a></dt> <dd><p>Decodes <em>obj</em> using the codec registered for <em>encoding</em>.</p> <p><em>Errors</em> may be given to set the desired error handling scheme. The default error handler is <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> meaning that decoding errors raise <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> (or a more codec specific subclass, such as <a class="reference internal" href="exceptions.html#UnicodeDecodeError" title="UnicodeDecodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeDecodeError</span></code></a>). Refer to <a class="reference internal" href="#codec-base-classes"><span class="std std-ref">Codec Base Classes</span></a> for more information on codec error handling.</p> </dd></dl> <p>The full details for each codec can also be looked up directly:</p> <dl class="function"> <dt id="codecs.lookup"> <code class="descclassname">codecs.</code><code class="descname">lookup</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.lookup" title="Permalink to this definition">¶</a></dt> <dd><p>Looks up the codec info in the Python codec registry and returns a <a class="reference internal" href="#codecs.CodecInfo" title="codecs.CodecInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">CodecInfo</span></code></a> object as defined below.</p> <p>Encodings are first looked up in the registry’s cache. If not found, the list of registered search functions is scanned. If no <a class="reference internal" href="#codecs.CodecInfo" title="codecs.CodecInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">CodecInfo</span></code></a> object is found, a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> is raised. Otherwise, the <a class="reference internal" href="#codecs.CodecInfo" title="codecs.CodecInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">CodecInfo</span></code></a> object is stored in the cache and returned to the caller.</p> </dd></dl> <dl class="class"> <dt id="codecs.CodecInfo"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">CodecInfo</code><span class="sig-paren">(</span><em>encode</em>, <em>decode</em>, <em>streamreader=None</em>, <em>streamwriter=None</em>, <em>incrementalencoder=None</em>, <em>incrementaldecoder=None</em>, <em>name=None</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.CodecInfo" title="Permalink to this definition">¶</a></dt> <dd><p>Codec details when looking up the codec registry. The constructor arguments are stored in attributes of the same name:</p> <dl class="attribute"> <dt id="codecs.CodecInfo.name"> <code class="descname">name</code><a class="headerlink" href="#codecs.CodecInfo.name" title="Permalink to this definition">¶</a></dt> <dd><p>The name of the encoding.</p> </dd></dl> <dl class="attribute"> <dt id="codecs.CodecInfo.encode"> <code class="descname">encode</code><a class="headerlink" href="#codecs.CodecInfo.encode" title="Permalink to this definition">¶</a></dt> <dt id="codecs.CodecInfo.decode"> <code class="descname">decode</code><a class="headerlink" href="#codecs.CodecInfo.decode" title="Permalink to this definition">¶</a></dt> <dd><p>The stateless encoding and decoding functions. These must be functions or methods which have the same interface as the <a class="reference internal" href="#codecs.Codec.encode" title="codecs.Codec.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">encode()</span></code></a> and <a class="reference internal" href="#codecs.Codec.decode" title="codecs.Codec.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decode()</span></code></a> methods of Codec instances (see <a class="reference internal" href="#codec-objects"><span class="std std-ref">Codec Interface</span></a>). The functions or methods are expected to work in a stateless mode.</p> </dd></dl> <dl class="attribute"> <dt id="codecs.CodecInfo.incrementalencoder"> <code class="descname">incrementalencoder</code><a class="headerlink" href="#codecs.CodecInfo.incrementalencoder" title="Permalink to this definition">¶</a></dt> <dt id="codecs.CodecInfo.incrementaldecoder"> <code class="descname">incrementaldecoder</code><a class="headerlink" href="#codecs.CodecInfo.incrementaldecoder" title="Permalink to this definition">¶</a></dt> <dd><p>Incremental encoder and decoder classes or factory functions. These have to provide the interface defined by the base classes <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> and <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a>, respectively. Incremental codecs can maintain state.</p> </dd></dl> <dl class="attribute"> <dt id="codecs.CodecInfo.streamwriter"> <code class="descname">streamwriter</code><a class="headerlink" href="#codecs.CodecInfo.streamwriter" title="Permalink to this definition">¶</a></dt> <dt id="codecs.CodecInfo.streamreader"> <code class="descname">streamreader</code><a class="headerlink" href="#codecs.CodecInfo.streamreader" title="Permalink to this definition">¶</a></dt> <dd><p>Stream writer and reader classes or factory functions. These have to provide the interface defined by the base classes <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> and <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a>, respectively. Stream codecs can maintain state.</p> </dd></dl> </dd></dl> <p>To simplify access to the various codec components, the module provides these additional functions which use <a class="reference internal" href="#codecs.lookup" title="codecs.lookup"><code class="xref py py-func docutils literal notranslate"><span class="pre">lookup()</span></code></a> for the codec lookup:</p> <dl class="function"> <dt id="codecs.getencoder"> <code class="descclassname">codecs.</code><code class="descname">getencoder</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getencoder" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its encoder function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found.</p> </dd></dl> <dl class="function"> <dt id="codecs.getdecoder"> <code class="descclassname">codecs.</code><code class="descname">getdecoder</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getdecoder" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its decoder function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found.</p> </dd></dl> <dl class="function"> <dt id="codecs.getincrementalencoder"> <code class="descclassname">codecs.</code><code class="descname">getincrementalencoder</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getincrementalencoder" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its incremental encoder class or factory function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found or the codec doesn’t support an incremental encoder.</p> </dd></dl> <dl class="function"> <dt id="codecs.getincrementaldecoder"> <code class="descclassname">codecs.</code><code class="descname">getincrementaldecoder</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getincrementaldecoder" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its incremental decoder class or factory function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found or the codec doesn’t support an incremental decoder.</p> </dd></dl> <dl class="function"> <dt id="codecs.getreader"> <code class="descclassname">codecs.</code><code class="descname">getreader</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getreader" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> class or factory function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found.</p> </dd></dl> <dl class="function"> <dt id="codecs.getwriter"> <code class="descclassname">codecs.</code><code class="descname">getwriter</code><span class="sig-paren">(</span><em>encoding</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.getwriter" title="Permalink to this definition">¶</a></dt> <dd><p>Look up the codec for the given encoding and return its <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> class or factory function.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the encoding cannot be found.</p> </dd></dl> <p>Custom codecs are made available by registering a suitable codec search function:</p> <dl class="function"> <dt id="codecs.register"> <code class="descclassname">codecs.</code><code class="descname">register</code><span class="sig-paren">(</span><em>search_function</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.register" title="Permalink to this definition">¶</a></dt> <dd><p>Register a codec search function. Search functions are expected to take one argument, being the encoding name in all lower case letters, and return a <a class="reference internal" href="#codecs.CodecInfo" title="codecs.CodecInfo"><code class="xref py py-class docutils literal notranslate"><span class="pre">CodecInfo</span></code></a> object. In case a search function cannot find a given encoding, it should return <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Search function registration is not currently reversible, which may cause problems in some cases, such as unit testing or module reloading.</p> </div> </dd></dl> <p>While the builtin <a class="reference internal" href="functions.html#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> and the associated <a class="reference internal" href="io.html#module-io" title="io: Core tools for working with streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">io</span></code></a> module are the recommended approach for working with encoded text files, this module provides additional utility functions and classes that allow the use of a wider range of codecs when working with binary files:</p> <dl class="function"> <dt id="codecs.open"> <code class="descclassname">codecs.</code><code class="descname">open</code><span class="sig-paren">(</span><em>filename</em>, <em>mode='r'</em>, <em>encoding=None</em>, <em>errors='strict'</em>, <em>buffering=1</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.open" title="Permalink to this definition">¶</a></dt> <dd><p>Open an encoded file using the given <em>mode</em> and return an instance of <a class="reference internal" href="#codecs.StreamReaderWriter" title="codecs.StreamReaderWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReaderWriter</span></code></a>, providing transparent encoding/decoding. The default file mode is <code class="docutils literal notranslate"><span class="pre">'r'</span></code>, meaning to open the file in read mode.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Underlying encoded files are always opened in binary mode. No automatic conversion of <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> is done on reading and writing. The <em>mode</em> argument may be any binary mode acceptable to the built-in <a class="reference internal" href="functions.html#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> function; the <code class="docutils literal notranslate"><span class="pre">'b'</span></code> is automatically added.</p> </div> <p><em>encoding</em> specifies the encoding which is to be used for the file. Any encoding that encodes to and decodes from bytes is allowed, and the data types supported by the file methods depend on the codec used.</p> <p><em>errors</em> may be given to define the error handling. It defaults to <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> which causes 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> to be raised in case an encoding error occurs.</p> <p><em>buffering</em> has the same meaning as for the built-in <a class="reference internal" href="functions.html#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> function. It defaults to line buffered.</p> </dd></dl> <dl class="function"> <dt id="codecs.EncodedFile"> <code class="descclassname">codecs.</code><code class="descname">EncodedFile</code><span class="sig-paren">(</span><em>file</em>, <em>data_encoding</em>, <em>file_encoding=None</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.EncodedFile" title="Permalink to this definition">¶</a></dt> <dd><p>Return a <a class="reference internal" href="#codecs.StreamRecoder" title="codecs.StreamRecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamRecoder</span></code></a> instance, a wrapped version of <em>file</em> which provides transparent transcoding. The original file is closed when the wrapped version is closed.</p> <p>Data written to the wrapped file is decoded according to the given <em>data_encoding</em> and then written to the original file as bytes using <em>file_encoding</em>. Bytes read from the original file are decoded according to <em>file_encoding</em>, and the result is encoded using <em>data_encoding</em>.</p> <p>If <em>file_encoding</em> is not given, it defaults to <em>data_encoding</em>.</p> <p><em>errors</em> may be given to define the error handling. It defaults to <code class="docutils literal notranslate"><span class="pre">'strict'</span></code>, which causes <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> to be raised in case an encoding error occurs.</p> </dd></dl> <dl class="function"> <dt id="codecs.iterencode"> <code class="descclassname">codecs.</code><code class="descname">iterencode</code><span class="sig-paren">(</span><em>iterator</em>, <em>encoding</em>, <em>errors='strict'</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.iterencode" title="Permalink to this definition">¶</a></dt> <dd><p>Uses an incremental encoder to iteratively encode the input provided by <em>iterator</em>. This function is a <a class="reference internal" href="../glossary.html#term-generator"><span class="xref std std-term">generator</span></a>. The <em>errors</em> argument (as well as any other keyword argument) is passed through to the incremental encoder.</p> <p>This function requires that the codec accept text <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> objects to encode. Therefore it does not support bytes-to-bytes encoders such as <code class="docutils literal notranslate"><span class="pre">base64_codec</span></code>.</p> </dd></dl> <dl class="function"> <dt id="codecs.iterdecode"> <code class="descclassname">codecs.</code><code class="descname">iterdecode</code><span class="sig-paren">(</span><em>iterator</em>, <em>encoding</em>, <em>errors='strict'</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.iterdecode" title="Permalink to this definition">¶</a></dt> <dd><p>Uses an incremental decoder to iteratively decode the input provided by <em>iterator</em>. This function is a <a class="reference internal" href="../glossary.html#term-generator"><span class="xref std std-term">generator</span></a>. The <em>errors</em> argument (as well as any other keyword argument) is passed through to the incremental decoder.</p> <p>This function requires that the codec accept <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> objects to decode. Therefore it does not support text-to-text encoders such as <code class="docutils literal notranslate"><span class="pre">rot_13</span></code>, although <code class="docutils literal notranslate"><span class="pre">rot_13</span></code> may be used equivalently with <a class="reference internal" href="#codecs.iterencode" title="codecs.iterencode"><code class="xref py py-func docutils literal notranslate"><span class="pre">iterencode()</span></code></a>.</p> </dd></dl> <p>The module also provides the following constants which are useful for reading and writing to platform dependent files:</p> <dl class="data"> <dt id="codecs.BOM"> <code class="descclassname">codecs.</code><code class="descname">BOM</code><a class="headerlink" href="#codecs.BOM" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_BE"> <code class="descclassname">codecs.</code><code class="descname">BOM_BE</code><a class="headerlink" href="#codecs.BOM_BE" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_LE"> <code class="descclassname">codecs.</code><code class="descname">BOM_LE</code><a class="headerlink" href="#codecs.BOM_LE" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF8"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF8</code><a class="headerlink" href="#codecs.BOM_UTF8" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF16"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF16</code><a class="headerlink" href="#codecs.BOM_UTF16" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF16_BE"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF16_BE</code><a class="headerlink" href="#codecs.BOM_UTF16_BE" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF16_LE"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF16_LE</code><a class="headerlink" href="#codecs.BOM_UTF16_LE" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF32"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF32</code><a class="headerlink" href="#codecs.BOM_UTF32" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF32_BE"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF32_BE</code><a class="headerlink" href="#codecs.BOM_UTF32_BE" title="Permalink to this definition">¶</a></dt> <dt id="codecs.BOM_UTF32_LE"> <code class="descclassname">codecs.</code><code class="descname">BOM_UTF32_LE</code><a class="headerlink" href="#codecs.BOM_UTF32_LE" title="Permalink to this definition">¶</a></dt> <dd><p>These constants define various byte sequences, being Unicode byte order marks (BOMs) for several encodings. They are used in UTF-16 and UTF-32 data streams to indicate the byte order used, and in UTF-8 as a Unicode signature. <a class="reference internal" href="#codecs.BOM_UTF16" title="codecs.BOM_UTF16"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16</span></code></a> is either <a class="reference internal" href="#codecs.BOM_UTF16_BE" title="codecs.BOM_UTF16_BE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16_BE</span></code></a> or <a class="reference internal" href="#codecs.BOM_UTF16_LE" title="codecs.BOM_UTF16_LE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16_LE</span></code></a> depending on the platform’s native byte order, <a class="reference internal" href="#codecs.BOM" title="codecs.BOM"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM</span></code></a> is an alias for <a class="reference internal" href="#codecs.BOM_UTF16" title="codecs.BOM_UTF16"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16</span></code></a>, <a class="reference internal" href="#codecs.BOM_LE" title="codecs.BOM_LE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_LE</span></code></a> for <a class="reference internal" href="#codecs.BOM_UTF16_LE" title="codecs.BOM_UTF16_LE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16_LE</span></code></a> and <a class="reference internal" href="#codecs.BOM_BE" title="codecs.BOM_BE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_BE</span></code></a> for <a class="reference internal" href="#codecs.BOM_UTF16_BE" title="codecs.BOM_UTF16_BE"><code class="xref py py-const docutils literal notranslate"><span class="pre">BOM_UTF16_BE</span></code></a>. The others represent the BOM in UTF-8 and UTF-32 encodings.</p> </dd></dl> <div class="section" id="codec-base-classes"> <span id="id1"></span><h2>7.2.1. Codec Base Classes<a class="headerlink" href="#codec-base-classes" title="Permalink to this headline">¶</a></h2> <p>The <a class="reference internal" href="#module-codecs" title="codecs: Encode and decode data and streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">codecs</span></code></a> module defines a set of base classes which define the interfaces for working with codec objects, and can also be used as the basis for custom codec implementations.</p> <p>Each codec has to define four interfaces to make it usable as codec in Python: stateless encoder, stateless decoder, stream reader and stream writer. The stream reader and writers typically reuse the stateless encoder/decoder to implement the file protocols. Codec authors also need to define how the codec will handle encoding and decoding errors.</p> <div class="section" id="error-handlers"> <span id="surrogateescape"></span><span id="id2"></span><h3>7.2.1.1. Error Handlers<a class="headerlink" href="#error-handlers" title="Permalink to this headline">¶</a></h3> <p>To simplify and standardize error handling, codecs may implement different error handling schemes by accepting the <em>errors</em> string argument. The following string values are defined and implemented by all standard Python codecs:</p> <table border="1" class="docutils"> <colgroup> <col width="35%" /> <col width="65%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Value</th> <th class="head">Meaning</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">'strict'</span></code></td> <td>Raise <a class="reference internal" href="exceptions.html#UnicodeError" title="UnicodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeError</span></code></a> (or a subclass); this is the default. Implemented in <a class="reference internal" href="#codecs.strict_errors" title="codecs.strict_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">strict_errors()</span></code></a>.</td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate"><span class="pre">'ignore'</span></code></td> <td>Ignore the malformed data and continue without further notice. Implemented in <a class="reference internal" href="#codecs.ignore_errors" title="codecs.ignore_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">ignore_errors()</span></code></a>.</td> </tr> </tbody> </table> <p>The following error handlers are only applicable to <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a>:</p> <table border="1" class="docutils"> <colgroup> <col width="35%" /> <col width="65%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Value</th> <th class="head">Meaning</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">'replace'</span></code></td> <td>Replace with a suitable replacement marker; Python will use the official <code class="docutils literal notranslate"><span class="pre">U+FFFD</span></code> REPLACEMENT CHARACTER for the built-in codecs on decoding, and ‘?’ on encoding. Implemented in <a class="reference internal" href="#codecs.replace_errors" title="codecs.replace_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">replace_errors()</span></code></a>.</td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate"><span class="pre">'xmlcharrefreplace'</span></code></td> <td>Replace with the appropriate XML character reference (only for encoding). Implemented in <a class="reference internal" href="#codecs.xmlcharrefreplace_errors" title="codecs.xmlcharrefreplace_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">xmlcharrefreplace_errors()</span></code></a>.</td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">'backslashreplace'</span></code></td> <td>Replace with backslashed escape sequences. Implemented in <a class="reference internal" href="#codecs.backslashreplace_errors" title="codecs.backslashreplace_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">backslashreplace_errors()</span></code></a>.</td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate"><span class="pre">'namereplace'</span></code></td> <td>Replace with <code class="docutils literal notranslate"><span class="pre">\N{...}</span></code> escape sequences (only for encoding). Implemented in <a class="reference internal" href="#codecs.namereplace_errors" title="codecs.namereplace_errors"><code class="xref py py-func docutils literal notranslate"><span class="pre">namereplace_errors()</span></code></a>.</td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">'surrogateescape'</span></code></td> <td>On decoding, replace byte with individual surrogate code ranging from <code class="docutils literal notranslate"><span class="pre">U+DC80</span></code> to <code class="docutils literal notranslate"><span class="pre">U+DCFF</span></code>. This code will then be turned back into the same byte when the <code class="docutils literal notranslate"><span class="pre">'surrogateescape'</span></code> error handler is used when encoding the data. (See <span class="target" id="index-1"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0383"><strong>PEP 383</strong></a> for more.)</td> </tr> </tbody> </table> <p>In addition, the following error handler is specific to the given codecs:</p> <table border="1" class="docutils"> <colgroup> <col width="22%" /> <col width="28%" /> <col width="50%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Value</th> <th class="head">Codecs</th> <th class="head">Meaning</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">'surrogatepass'</span></code></td> <td>utf-8, utf-16, utf-32, utf-16-be, utf-16-le, utf-32-be, utf-32-le</td> <td>Allow encoding and decoding of surrogate codes. These codecs normally treat the presence of surrogates as an error.</td> </tr> </tbody> </table> <div class="versionadded"> <p><span class="versionmodified">New in version 3.1: </span>The <code class="docutils literal notranslate"><span class="pre">'surrogateescape'</span></code> and <code class="docutils literal notranslate"><span class="pre">'surrogatepass'</span></code> error handlers.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.4: </span>The <code class="docutils literal notranslate"><span class="pre">'surrogatepass'</span></code> error handlers now works with utf-16* and utf-32* codecs.</p> </div> <div class="versionadded"> <p><span class="versionmodified">New in version 3.5: </span>The <code class="docutils literal notranslate"><span class="pre">'namereplace'</span></code> error handler.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.5: </span>The <code class="docutils literal notranslate"><span class="pre">'backslashreplace'</span></code> error handlers now works with decoding and translating.</p> </div> <p>The set of allowed values can be extended by registering a new named error handler:</p> <dl class="function"> <dt id="codecs.register_error"> <code class="descclassname">codecs.</code><code class="descname">register_error</code><span class="sig-paren">(</span><em>name</em>, <em>error_handler</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.register_error" title="Permalink to this definition">¶</a></dt> <dd><p>Register the error handling function <em>error_handler</em> under the name <em>name</em>. The <em>error_handler</em> argument will be called during encoding and decoding in case of an error, when <em>name</em> is specified as the errors parameter.</p> <p>For encoding, <em>error_handler</em> will be called with a <a class="reference internal" href="exceptions.html#UnicodeEncodeError" title="UnicodeEncodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeEncodeError</span></code></a> instance, which contains information about the location of the error. The error handler must either raise this or a different exception, or return a tuple with a replacement for the unencodable part of the input and a position where encoding should continue. The replacement may be either <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> or <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>. If the replacement is bytes, the encoder will simply copy them into the output buffer. If the replacement is a string, the encoder will encode the replacement. Encoding continues on original input at the specified position. Negative position values will be treated as being relative to the end of the input string. If the resulting position is out of bound an <a class="reference internal" href="exceptions.html#IndexError" title="IndexError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IndexError</span></code></a> will be raised.</p> <p>Decoding and translating works similarly, except <a class="reference internal" href="exceptions.html#UnicodeDecodeError" title="UnicodeDecodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeDecodeError</span></code></a> or <a class="reference internal" href="exceptions.html#UnicodeTranslateError" title="UnicodeTranslateError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeTranslateError</span></code></a> will be passed to the handler and that the replacement from the error handler will be put into the output directly.</p> </dd></dl> <p>Previously registered error handlers (including the standard error handlers) can be looked up by name:</p> <dl class="function"> <dt id="codecs.lookup_error"> <code class="descclassname">codecs.</code><code class="descname">lookup_error</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.lookup_error" title="Permalink to this definition">¶</a></dt> <dd><p>Return the error handler previously registered under the name <em>name</em>.</p> <p>Raises a <a class="reference internal" href="exceptions.html#LookupError" title="LookupError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">LookupError</span></code></a> in case the handler cannot be found.</p> </dd></dl> <p>The following standard error handlers are also made available as module level functions:</p> <dl class="function"> <dt id="codecs.strict_errors"> <code class="descclassname">codecs.</code><code class="descname">strict_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.strict_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> error handling: each encoding or decoding error raises a <a class="reference internal" href="exceptions.html#UnicodeError" title="UnicodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeError</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="codecs.replace_errors"> <code class="descclassname">codecs.</code><code class="descname">replace_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.replace_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'replace'</span></code> error handling (for <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a> only): substitutes <code class="docutils literal notranslate"><span class="pre">'?'</span></code> for encoding errors (to be encoded by the codec), and <code class="docutils literal notranslate"><span class="pre">'\ufffd'</span></code> (the Unicode replacement character) for decoding errors.</p> </dd></dl> <dl class="function"> <dt id="codecs.ignore_errors"> <code class="descclassname">codecs.</code><code class="descname">ignore_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.ignore_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'ignore'</span></code> error handling: malformed data is ignored and encoding or decoding is continued without further notice.</p> </dd></dl> <dl class="function"> <dt id="codecs.xmlcharrefreplace_errors"> <code class="descclassname">codecs.</code><code class="descname">xmlcharrefreplace_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.xmlcharrefreplace_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'xmlcharrefreplace'</span></code> error handling (for encoding with <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a> only): the unencodable character is replaced by an appropriate XML character reference.</p> </dd></dl> <dl class="function"> <dt id="codecs.backslashreplace_errors"> <code class="descclassname">codecs.</code><code class="descname">backslashreplace_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.backslashreplace_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'backslashreplace'</span></code> error handling (for <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a> only): malformed data is replaced by a backslashed escape sequence.</p> </dd></dl> <dl class="function"> <dt id="codecs.namereplace_errors"> <code class="descclassname">codecs.</code><code class="descname">namereplace_errors</code><span class="sig-paren">(</span><em>exception</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.namereplace_errors" title="Permalink to this definition">¶</a></dt> <dd><p>Implements the <code class="docutils literal notranslate"><span class="pre">'namereplace'</span></code> error handling (for encoding with <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a> only): the unencodable character is replaced by a <code class="docutils literal notranslate"><span class="pre">\N{...}</span></code> escape sequence.</p> <div class="versionadded"> <p><span class="versionmodified">New in version 3.5.</span></p> </div> </dd></dl> </div> <div class="section" id="stateless-encoding-and-decoding"> <span id="codec-objects"></span><h3>7.2.1.2. Stateless Encoding and Decoding<a class="headerlink" href="#stateless-encoding-and-decoding" title="Permalink to this headline">¶</a></h3> <p>The base <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> class defines these methods which also define the function interfaces of the stateless encoder and decoder:</p> <dl class="method"> <dt id="codecs.Codec.encode"> <code class="descclassname">Codec.</code><code class="descname">encode</code><span class="sig-paren">(</span><em>input</em><span class="optional">[</span>, <em>errors</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.Codec.encode" title="Permalink to this definition">¶</a></dt> <dd><p>Encodes the object <em>input</em> and returns a tuple (output object, length consumed). For instance, <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encoding</span></a> converts a string object to a bytes object using a particular character set encoding (e.g., <code class="docutils literal notranslate"><span class="pre">cp1252</span></code> or <code class="docutils literal notranslate"><span class="pre">iso-8859-1</span></code>).</p> <p>The <em>errors</em> argument defines the error handling to apply. It defaults to <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> handling.</p> <p>The method may not store state in the <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> instance. Use <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> for codecs which have to keep state in order to make encoding efficient.</p> <p>The encoder must be able to handle zero length input and return an empty object of the output object type in this situation.</p> </dd></dl> <dl class="method"> <dt id="codecs.Codec.decode"> <code class="descclassname">Codec.</code><code class="descname">decode</code><span class="sig-paren">(</span><em>input</em><span class="optional">[</span>, <em>errors</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.Codec.decode" title="Permalink to this definition">¶</a></dt> <dd><p>Decodes the object <em>input</em> and returns a tuple (output object, length consumed). For instance, for a <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encoding</span></a>, decoding converts a bytes object encoded using a particular character set encoding to a string object.</p> <p>For text encodings and bytes-to-bytes codecs, <em>input</em> must be a bytes object or one which provides the read-only buffer interface – for example, buffer objects and memory mapped files.</p> <p>The <em>errors</em> argument defines the error handling to apply. It defaults to <code class="docutils literal notranslate"><span class="pre">'strict'</span></code> handling.</p> <p>The method may not store state in the <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> instance. Use <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> for codecs which have to keep state in order to make decoding efficient.</p> <p>The decoder must be able to handle zero length input and return an empty object of the output object type in this situation.</p> </dd></dl> </div> <div class="section" id="incremental-encoding-and-decoding"> <h3>7.2.1.3. Incremental Encoding and Decoding<a class="headerlink" href="#incremental-encoding-and-decoding" title="Permalink to this headline">¶</a></h3> <p>The <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> and <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a> classes provide the basic interface for incremental encoding and decoding. Encoding/decoding the input isn’t done with one call to the stateless encoder/decoder function, but with multiple calls to the <a class="reference internal" href="#codecs.IncrementalEncoder.encode" title="codecs.IncrementalEncoder.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">encode()</span></code></a>/<a class="reference internal" href="#codecs.IncrementalDecoder.decode" title="codecs.IncrementalDecoder.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decode()</span></code></a> method of the incremental encoder/decoder. The incremental encoder/decoder keeps track of the encoding/decoding process during method calls.</p> <p>The joined output of calls to the <a class="reference internal" href="#codecs.IncrementalEncoder.encode" title="codecs.IncrementalEncoder.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">encode()</span></code></a>/<a class="reference internal" href="#codecs.IncrementalDecoder.decode" title="codecs.IncrementalDecoder.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decode()</span></code></a> method is the same as if all the single inputs were joined into one, and this input was encoded/decoded with the stateless encoder/decoder.</p> <div class="section" id="incrementalencoder-objects"> <span id="incremental-encoder-objects"></span><h4>7.2.1.3.1. IncrementalEncoder Objects<a class="headerlink" href="#incrementalencoder-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> class is used for encoding an input in multiple steps. It defines the following methods which every incremental encoder must define in order to be compatible with the Python codec registry.</p> <dl class="class"> <dt id="codecs.IncrementalEncoder"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">IncrementalEncoder</code><span class="sig-paren">(</span><em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalEncoder" title="Permalink to this definition">¶</a></dt> <dd><p>Constructor for an <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> instance.</p> <p>All incremental encoders must provide this constructor interface. They are free to add additional keyword arguments, but only the ones defined here are used by the Python codec registry.</p> <p>The <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> may implement different error handling schemes by providing the <em>errors</em> keyword argument. See <a class="reference internal" href="#error-handlers"><span class="std std-ref">Error Handlers</span></a> for possible values.</p> <p>The <em>errors</em> argument will be assigned to an attribute of the same name. Assigning to this attribute makes it possible to switch between different error handling strategies during the lifetime of the <a class="reference internal" href="#codecs.IncrementalEncoder" title="codecs.IncrementalEncoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalEncoder</span></code></a> object.</p> <dl class="method"> <dt id="codecs.IncrementalEncoder.encode"> <code class="descname">encode</code><span class="sig-paren">(</span><em>object</em><span class="optional">[</span>, <em>final</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalEncoder.encode" title="Permalink to this definition">¶</a></dt> <dd><p>Encodes <em>object</em> (taking the current state of the encoder into account) and returns the resulting encoded object. If this is the last call to <a class="reference internal" href="#codecs.encode" title="codecs.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">encode()</span></code></a> <em>final</em> must be true (the default is false).</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalEncoder.reset"> <code class="descname">reset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalEncoder.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Reset the encoder to the initial state. The output is discarded: call <code class="docutils literal notranslate"><span class="pre">.encode(object,</span> <span class="pre">final=True)</span></code>, passing an empty byte or text string if necessary, to reset the encoder and to get the output.</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalEncoder.getstate"> <code class="descname">getstate</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalEncoder.getstate" title="Permalink to this definition">¶</a></dt> <dd><p>Return the current state of the encoder which must be an integer. The implementation should make sure that <code class="docutils literal notranslate"><span class="pre">0</span></code> is the most common state. (States that are more complicated than integers can be converted into an integer by marshaling/pickling the state and encoding the bytes of the resulting string into an integer).</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalEncoder.setstate"> <code class="descname">setstate</code><span class="sig-paren">(</span><em>state</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalEncoder.setstate" title="Permalink to this definition">¶</a></dt> <dd><p>Set the state of the encoder to <em>state</em>. <em>state</em> must be an encoder state returned by <a class="reference internal" href="#codecs.IncrementalEncoder.getstate" title="codecs.IncrementalEncoder.getstate"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getstate()</span></code></a>.</p> </dd></dl> </dd></dl> </div> <div class="section" id="incrementaldecoder-objects"> <span id="incremental-decoder-objects"></span><h4>7.2.1.3.2. IncrementalDecoder Objects<a class="headerlink" href="#incrementaldecoder-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a> class is used for decoding an input in multiple steps. It defines the following methods which every incremental decoder must define in order to be compatible with the Python codec registry.</p> <dl class="class"> <dt id="codecs.IncrementalDecoder"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">IncrementalDecoder</code><span class="sig-paren">(</span><em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalDecoder" title="Permalink to this definition">¶</a></dt> <dd><p>Constructor for an <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a> instance.</p> <p>All incremental decoders must provide this constructor interface. They are free to add additional keyword arguments, but only the ones defined here are used by the Python codec registry.</p> <p>The <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a> may implement different error handling schemes by providing the <em>errors</em> keyword argument. See <a class="reference internal" href="#error-handlers"><span class="std std-ref">Error Handlers</span></a> for possible values.</p> <p>The <em>errors</em> argument will be assigned to an attribute of the same name. Assigning to this attribute makes it possible to switch between different error handling strategies during the lifetime of the <a class="reference internal" href="#codecs.IncrementalDecoder" title="codecs.IncrementalDecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">IncrementalDecoder</span></code></a> object.</p> <dl class="method"> <dt id="codecs.IncrementalDecoder.decode"> <code class="descname">decode</code><span class="sig-paren">(</span><em>object</em><span class="optional">[</span>, <em>final</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalDecoder.decode" title="Permalink to this definition">¶</a></dt> <dd><p>Decodes <em>object</em> (taking the current state of the decoder into account) and returns the resulting decoded object. If this is the last call to <a class="reference internal" href="#codecs.decode" title="codecs.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">decode()</span></code></a> <em>final</em> must be true (the default is false). If <em>final</em> is true the decoder must decode the input completely and must flush all buffers. If this isn’t possible (e.g. because of incomplete byte sequences at the end of the input) it must initiate error handling just like in the stateless case (which might raise an exception).</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalDecoder.reset"> <code class="descname">reset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalDecoder.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Reset the decoder to the initial state.</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalDecoder.getstate"> <code class="descname">getstate</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalDecoder.getstate" title="Permalink to this definition">¶</a></dt> <dd><p>Return the current state of the decoder. This must be a tuple with two items, the first must be the buffer containing the still undecoded input. The second must be an integer and can be additional state info. (The implementation should make sure that <code class="docutils literal notranslate"><span class="pre">0</span></code> is the most common additional state info.) If this additional state info is <code class="docutils literal notranslate"><span class="pre">0</span></code> it must be possible to set the decoder to the state which has no input buffered and <code class="docutils literal notranslate"><span class="pre">0</span></code> as the additional state info, so that feeding the previously buffered input to the decoder returns it to the previous state without producing any output. (Additional state info that is more complicated than integers can be converted into an integer by marshaling/pickling the info and encoding the bytes of the resulting string into an integer.)</p> </dd></dl> <dl class="method"> <dt id="codecs.IncrementalDecoder.setstate"> <code class="descname">setstate</code><span class="sig-paren">(</span><em>state</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.IncrementalDecoder.setstate" title="Permalink to this definition">¶</a></dt> <dd><p>Set the state of the encoder to <em>state</em>. <em>state</em> must be a decoder state returned by <a class="reference internal" href="#codecs.IncrementalDecoder.getstate" title="codecs.IncrementalDecoder.getstate"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getstate()</span></code></a>.</p> </dd></dl> </dd></dl> </div> </div> <div class="section" id="stream-encoding-and-decoding"> <h3>7.2.1.4. Stream Encoding and Decoding<a class="headerlink" href="#stream-encoding-and-decoding" title="Permalink to this headline">¶</a></h3> <p>The <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> and <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> classes provide generic working interfaces which can be used to implement new encoding submodules very easily. See <code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.utf_8</span></code> for an example of how this is done.</p> <div class="section" id="streamwriter-objects"> <span id="stream-writer-objects"></span><h4>7.2.1.4.1. StreamWriter Objects<a class="headerlink" href="#streamwriter-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> class is a subclass of <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> and defines the following methods which every stream writer must define in order to be compatible with the Python codec registry.</p> <dl class="class"> <dt id="codecs.StreamWriter"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">StreamWriter</code><span class="sig-paren">(</span><em>stream</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamWriter" title="Permalink to this definition">¶</a></dt> <dd><p>Constructor for a <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> instance.</p> <p>All stream writers must provide this constructor interface. They are free to add additional keyword arguments, but only the ones defined here are used by the Python codec registry.</p> <p>The <em>stream</em> argument must be a file-like object open for writing text or binary data, as appropriate for the specific codec.</p> <p>The <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> may implement different error handling schemes by providing the <em>errors</em> keyword argument. See <a class="reference internal" href="#error-handlers"><span class="std std-ref">Error Handlers</span></a> for the standard error handlers the underlying stream codec may support.</p> <p>The <em>errors</em> argument will be assigned to an attribute of the same name. Assigning to this attribute makes it possible to switch between different error handling strategies during the lifetime of the <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> object.</p> <dl class="method"> <dt id="codecs.StreamWriter.write"> <code class="descname">write</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamWriter.write" title="Permalink to this definition">¶</a></dt> <dd><p>Writes the object’s contents encoded to the stream.</p> </dd></dl> <dl class="method"> <dt id="codecs.StreamWriter.writelines"> <code class="descname">writelines</code><span class="sig-paren">(</span><em>list</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamWriter.writelines" title="Permalink to this definition">¶</a></dt> <dd><p>Writes the concatenated list of strings to the stream (possibly by reusing the <a class="reference internal" href="#codecs.StreamWriter.write" title="codecs.StreamWriter.write"><code class="xref py py-meth docutils literal notranslate"><span class="pre">write()</span></code></a> method). The standard bytes-to-bytes codecs do not support this method.</p> </dd></dl> <dl class="method"> <dt id="codecs.StreamWriter.reset"> <code class="descname">reset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamWriter.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Flushes and resets the codec buffers used for keeping state.</p> <p>Calling this method should ensure that the data on the output is put into a clean state that allows appending of new fresh data without having to rescan the whole stream to recover state.</p> </dd></dl> </dd></dl> <p>In addition to the above methods, the <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> must also inherit all other methods and attributes from the underlying stream.</p> </div> <div class="section" id="streamreader-objects"> <span id="stream-reader-objects"></span><h4>7.2.1.4.2. StreamReader Objects<a class="headerlink" href="#streamreader-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> class is a subclass of <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> and defines the following methods which every stream reader must define in order to be compatible with the Python codec registry.</p> <dl class="class"> <dt id="codecs.StreamReader"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">StreamReader</code><span class="sig-paren">(</span><em>stream</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReader" title="Permalink to this definition">¶</a></dt> <dd><p>Constructor for a <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> instance.</p> <p>All stream readers must provide this constructor interface. They are free to add additional keyword arguments, but only the ones defined here are used by the Python codec registry.</p> <p>The <em>stream</em> argument must be a file-like object open for reading text or binary data, as appropriate for the specific codec.</p> <p>The <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> may implement different error handling schemes by providing the <em>errors</em> keyword argument. See <a class="reference internal" href="#error-handlers"><span class="std std-ref">Error Handlers</span></a> for the standard error handlers the underlying stream codec may support.</p> <p>The <em>errors</em> argument will be assigned to an attribute of the same name. Assigning to this attribute makes it possible to switch between different error handling strategies during the lifetime of the <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> object.</p> <p>The set of allowed values for the <em>errors</em> argument can be extended with <a class="reference internal" href="#codecs.register_error" title="codecs.register_error"><code class="xref py py-func docutils literal notranslate"><span class="pre">register_error()</span></code></a>.</p> <dl class="method"> <dt id="codecs.StreamReader.read"> <code class="descname">read</code><span class="sig-paren">(</span><span class="optional">[</span><em>size</em><span class="optional">[</span>, <em>chars</em><span class="optional">[</span>, <em>firstline</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReader.read" title="Permalink to this definition">¶</a></dt> <dd><p>Decodes data from the stream and returns the resulting object.</p> <p>The <em>chars</em> argument indicates the number of decoded code points or bytes to return. The <a class="reference internal" href="#codecs.StreamReader.read" title="codecs.StreamReader.read"><code class="xref py py-func docutils literal notranslate"><span class="pre">read()</span></code></a> method will never return more data than requested, but it might return less, if there is not enough available.</p> <p>The <em>size</em> argument indicates the approximate maximum number of encoded bytes or code points to read for decoding. The decoder can modify this setting as appropriate. The default value -1 indicates to read and decode as much as possible. This parameter is intended to prevent having to decode huge files in one step.</p> <p>The <em>firstline</em> flag indicates that it would be sufficient to only return the first line, if there are decoding errors on later lines.</p> <p>The method should use a greedy read strategy meaning that it should read as much data as is allowed within the definition of the encoding and the given size, e.g. if optional encoding endings or state markers are available on the stream, these should be read too.</p> </dd></dl> <dl class="method"> <dt id="codecs.StreamReader.readline"> <code class="descname">readline</code><span class="sig-paren">(</span><span class="optional">[</span><em>size</em><span class="optional">[</span>, <em>keepends</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReader.readline" title="Permalink to this definition">¶</a></dt> <dd><p>Read one line from the input stream and return the decoded data.</p> <p><em>size</em>, if given, is passed as size argument to the stream’s <a class="reference internal" href="#codecs.StreamReader.read" title="codecs.StreamReader.read"><code class="xref py py-meth docutils literal notranslate"><span class="pre">read()</span></code></a> method.</p> <p>If <em>keepends</em> is false line-endings will be stripped from the lines returned.</p> </dd></dl> <dl class="method"> <dt id="codecs.StreamReader.readlines"> <code class="descname">readlines</code><span class="sig-paren">(</span><span class="optional">[</span><em>sizehint</em><span class="optional">[</span>, <em>keepends</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReader.readlines" title="Permalink to this definition">¶</a></dt> <dd><p>Read all lines available on the input stream and return them as a list of lines.</p> <p>Line-endings are implemented using the codec’s decoder method and are included in the list entries if <em>keepends</em> is true.</p> <p><em>sizehint</em>, if given, is passed as the <em>size</em> argument to the stream’s <a class="reference internal" href="#codecs.StreamReader.read" title="codecs.StreamReader.read"><code class="xref py py-meth docutils literal notranslate"><span class="pre">read()</span></code></a> method.</p> </dd></dl> <dl class="method"> <dt id="codecs.StreamReader.reset"> <code class="descname">reset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReader.reset" title="Permalink to this definition">¶</a></dt> <dd><p>Resets the codec buffers used for keeping state.</p> <p>Note that no stream repositioning should take place. This method is primarily intended to be able to recover from decoding errors.</p> </dd></dl> </dd></dl> <p>In addition to the above methods, the <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> must also inherit all other methods and attributes from the underlying stream.</p> </div> <div class="section" id="streamreaderwriter-objects"> <span id="stream-reader-writer"></span><h4>7.2.1.4.3. StreamReaderWriter Objects<a class="headerlink" href="#streamreaderwriter-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.StreamReaderWriter" title="codecs.StreamReaderWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReaderWriter</span></code></a> is a convenience class that allows wrapping streams which work in both read and write modes.</p> <p>The design is such that one can use the factory functions returned by the <a class="reference internal" href="#codecs.lookup" title="codecs.lookup"><code class="xref py py-func docutils literal notranslate"><span class="pre">lookup()</span></code></a> function to construct the instance.</p> <dl class="class"> <dt id="codecs.StreamReaderWriter"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">StreamReaderWriter</code><span class="sig-paren">(</span><em>stream</em>, <em>Reader</em>, <em>Writer</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamReaderWriter" title="Permalink to this definition">¶</a></dt> <dd><p>Creates a <a class="reference internal" href="#codecs.StreamReaderWriter" title="codecs.StreamReaderWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReaderWriter</span></code></a> instance. <em>stream</em> must be a file-like object. <em>Reader</em> and <em>Writer</em> must be factory functions or classes providing the <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> and <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> interface resp. Error handling is done in the same way as defined for the stream readers and writers.</p> </dd></dl> <p><a class="reference internal" href="#codecs.StreamReaderWriter" title="codecs.StreamReaderWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReaderWriter</span></code></a> instances define the combined interfaces of <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> and <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> classes. They inherit all other methods and attributes from the underlying stream.</p> </div> <div class="section" id="streamrecoder-objects"> <span id="stream-recoder-objects"></span><h4>7.2.1.4.4. StreamRecoder Objects<a class="headerlink" href="#streamrecoder-objects" title="Permalink to this headline">¶</a></h4> <p>The <a class="reference internal" href="#codecs.StreamRecoder" title="codecs.StreamRecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamRecoder</span></code></a> translates data from one encoding to another, which is sometimes useful when dealing with different encoding environments.</p> <p>The design is such that one can use the factory functions returned by the <a class="reference internal" href="#codecs.lookup" title="codecs.lookup"><code class="xref py py-func docutils literal notranslate"><span class="pre">lookup()</span></code></a> function to construct the instance.</p> <dl class="class"> <dt id="codecs.StreamRecoder"> <em class="property">class </em><code class="descclassname">codecs.</code><code class="descname">StreamRecoder</code><span class="sig-paren">(</span><em>stream</em>, <em>encode</em>, <em>decode</em>, <em>Reader</em>, <em>Writer</em>, <em>errors='strict'</em><span class="sig-paren">)</span><a class="headerlink" href="#codecs.StreamRecoder" title="Permalink to this definition">¶</a></dt> <dd><p>Creates a <a class="reference internal" href="#codecs.StreamRecoder" title="codecs.StreamRecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamRecoder</span></code></a> instance which implements a two-way conversion: <em>encode</em> and <em>decode</em> work on the frontend — the data visible to code calling <code class="xref py py-meth docutils literal notranslate"><span class="pre">read()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">write()</span></code>, while <em>Reader</em> and <em>Writer</em> work on the backend — the data in <em>stream</em>.</p> <p>You can use these objects to do transparent transcodings from e.g. Latin-1 to UTF-8 and back.</p> <p>The <em>stream</em> argument must be a file-like object.</p> <p>The <em>encode</em> and <em>decode</em> arguments must adhere to the <code class="xref py py-class docutils literal notranslate"><span class="pre">Codec</span></code> interface. <em>Reader</em> and <em>Writer</em> must be factory functions or classes providing objects of the <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> and <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> interface respectively.</p> <p>Error handling is done in the same way as defined for the stream readers and writers.</p> </dd></dl> <p><a class="reference internal" href="#codecs.StreamRecoder" title="codecs.StreamRecoder"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamRecoder</span></code></a> instances define the combined interfaces of <a class="reference internal" href="#codecs.StreamReader" title="codecs.StreamReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamReader</span></code></a> and <a class="reference internal" href="#codecs.StreamWriter" title="codecs.StreamWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">StreamWriter</span></code></a> classes. They inherit all other methods and attributes from the underlying stream.</p> </div> </div> </div> <div class="section" id="encodings-and-unicode"> <span id="encodings-overview"></span><h2>7.2.2. Encodings and Unicode<a class="headerlink" href="#encodings-and-unicode" title="Permalink to this headline">¶</a></h2> <p>Strings are stored internally as sequences of code points in range <code class="docutils literal notranslate"><span class="pre">0x0</span></code>–<code class="docutils literal notranslate"><span class="pre">0x10FFFF</span></code>. (See <span class="target" id="index-2"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0393"><strong>PEP 393</strong></a> for more details about the implementation.) Once a string object is used outside of CPU and memory, endianness and how these arrays are stored as bytes become an issue. As with other codecs, serialising a string into a sequence of bytes is known as <em>encoding</em>, and recreating the string from the sequence of bytes is known as <em>decoding</em>. There are a variety of different text serialisation codecs, which are collectivity referred to as <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encodings</span></a>.</p> <p>The simplest text encoding (called <code class="docutils literal notranslate"><span class="pre">'latin-1'</span></code> or <code class="docutils literal notranslate"><span class="pre">'iso-8859-1'</span></code>) maps the code points 0–255 to the bytes <code class="docutils literal notranslate"><span class="pre">0x0</span></code>–<code class="docutils literal notranslate"><span class="pre">0xff</span></code>, which means that a string object that contains code points above <code class="docutils literal notranslate"><span class="pre">U+00FF</span></code> can’t be encoded with this codec. Doing so will raise a <a class="reference internal" href="exceptions.html#UnicodeEncodeError" title="UnicodeEncodeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">UnicodeEncodeError</span></code></a> that looks like the following (although the details of the error message may differ): <code class="docutils literal notranslate"><span class="pre">UnicodeEncodeError:</span> <span class="pre">'latin-1'</span> <span class="pre">codec</span> <span class="pre">can't</span> <span class="pre">encode</span> <span class="pre">character</span> <span class="pre">'\u1234'</span> <span class="pre">in</span> <span class="pre">position</span> <span class="pre">3:</span> <span class="pre">ordinal</span> <span class="pre">not</span> <span class="pre">in</span> <span class="pre">range(256)</span></code>.</p> <p>There’s another group of encodings (the so called charmap encodings) that choose a different subset of all Unicode code points and how these code points are mapped to the bytes <code class="docutils literal notranslate"><span class="pre">0x0</span></code>–<code class="docutils literal notranslate"><span class="pre">0xff</span></code>. To see how this is done simply open e.g. <code class="file docutils literal notranslate"><span class="pre">encodings/cp1252.py</span></code> (which is an encoding that is used primarily on Windows). There’s a string constant with 256 characters that shows you which character is mapped to which byte value.</p> <p>All of these encodings can only encode 256 of the 1114112 code points defined in Unicode. A simple and straightforward way that can store each Unicode code point, is to store each code point as four consecutive bytes. There are two possibilities: store the bytes in big endian or in little endian order. These two encodings are called <code class="docutils literal notranslate"><span class="pre">UTF-32-BE</span></code> and <code class="docutils literal notranslate"><span class="pre">UTF-32-LE</span></code> respectively. Their disadvantage is that if e.g. you use <code class="docutils literal notranslate"><span class="pre">UTF-32-BE</span></code> on a little endian machine you will always have to swap bytes on encoding and decoding. <code class="docutils literal notranslate"><span class="pre">UTF-32</span></code> avoids this problem: bytes will always be in natural endianness. When these bytes are read by a CPU with a different endianness, then bytes have to be swapped though. To be able to detect the endianness of a <code class="docutils literal notranslate"><span class="pre">UTF-16</span></code> or <code class="docutils literal notranslate"><span class="pre">UTF-32</span></code> byte sequence, there’s the so called BOM (“Byte Order Mark”). This is the Unicode character <code class="docutils literal notranslate"><span class="pre">U+FEFF</span></code>. This character can be prepended to every <code class="docutils literal notranslate"><span class="pre">UTF-16</span></code> or <code class="docutils literal notranslate"><span class="pre">UTF-32</span></code> byte sequence. The byte swapped version of this character (<code class="docutils literal notranslate"><span class="pre">0xFFFE</span></code>) is an illegal character that may not appear in a Unicode text. So when the first character in an <code class="docutils literal notranslate"><span class="pre">UTF-16</span></code> or <code class="docutils literal notranslate"><span class="pre">UTF-32</span></code> byte sequence appears to be a <code class="docutils literal notranslate"><span class="pre">U+FFFE</span></code> the bytes have to be swapped on decoding. Unfortunately the character <code class="docutils literal notranslate"><span class="pre">U+FEFF</span></code> had a second purpose as a <code class="docutils literal notranslate"><span class="pre">ZERO</span> <span class="pre">WIDTH</span> <span class="pre">NO-BREAK</span> <span class="pre">SPACE</span></code>: a character that has no width and doesn’t allow a word to be split. It can e.g. be used to give hints to a ligature algorithm. With Unicode 4.0 using <code class="docutils literal notranslate"><span class="pre">U+FEFF</span></code> as a <code class="docutils literal notranslate"><span class="pre">ZERO</span> <span class="pre">WIDTH</span> <span class="pre">NO-BREAK</span> <span class="pre">SPACE</span></code> has been deprecated (with <code class="docutils literal notranslate"><span class="pre">U+2060</span></code> (<code class="docutils literal notranslate"><span class="pre">WORD</span> <span class="pre">JOINER</span></code>) assuming this role). Nevertheless Unicode software still must be able to handle <code class="docutils literal notranslate"><span class="pre">U+FEFF</span></code> in both roles: as a BOM it’s a device to determine the storage layout of the encoded bytes, and vanishes once the byte sequence has been decoded into a string; as a <code class="docutils literal notranslate"><span class="pre">ZERO</span> <span class="pre">WIDTH</span> <span class="pre">NO-BREAK</span> <span class="pre">SPACE</span></code> it’s a normal character that will be decoded like any other.</p> <p>There’s another encoding that is able to encoding the full range of Unicode characters: UTF-8. UTF-8 is an 8-bit encoding, which means there are no issues with byte order in UTF-8. Each byte in a UTF-8 byte sequence consists of two parts: marker bits (the most significant bits) and payload bits. The marker bits are a sequence of zero to four <code class="docutils literal notranslate"><span class="pre">1</span></code> bits followed by a <code class="docutils literal notranslate"><span class="pre">0</span></code> bit. Unicode characters are encoded like this (with x being payload bits, which when concatenated give the Unicode character):</p> <table border="1" class="docutils"> <colgroup> <col width="43%" /> <col width="57%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Range</th> <th class="head">Encoding</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">U-00000000</span></code> … <code class="docutils literal notranslate"><span class="pre">U-0000007F</span></code></td> <td>0xxxxxxx</td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate"><span class="pre">U-00000080</span></code> … <code class="docutils literal notranslate"><span class="pre">U-000007FF</span></code></td> <td>110xxxxx 10xxxxxx</td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate"><span class="pre">U-00000800</span></code> … <code class="docutils literal notranslate"><span class="pre">U-0000FFFF</span></code></td> <td>1110xxxx 10xxxxxx 10xxxxxx</td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate"><span class="pre">U-00010000</span></code> … <code class="docutils literal notranslate"><span class="pre">U-0010FFFF</span></code></td> <td>11110xxx 10xxxxxx 10xxxxxx 10xxxxxx</td> </tr> </tbody> </table> <p>The least significant bit of the Unicode character is the rightmost x bit.</p> <p>As UTF-8 is an 8-bit encoding no BOM is required and any <code class="docutils literal notranslate"><span class="pre">U+FEFF</span></code> character in the decoded string (even if it’s the first character) is treated as a <code class="docutils literal notranslate"><span class="pre">ZERO</span> <span class="pre">WIDTH</span> <span class="pre">NO-BREAK</span> <span class="pre">SPACE</span></code>.</p> <p>Without external information it’s impossible to reliably determine which encoding was used for encoding a string. Each charmap encoding can decode any random byte sequence. However that’s not possible with UTF-8, as UTF-8 byte sequences have a structure that doesn’t allow arbitrary byte sequences. To increase the reliability with which a UTF-8 encoding can be detected, Microsoft invented a variant of UTF-8 (that Python 2.5 calls <code class="docutils literal notranslate"><span class="pre">"utf-8-sig"</span></code>) for its Notepad program: Before any of the Unicode characters is written to the file, a UTF-8 encoded BOM (which looks like this as a byte sequence: <code class="docutils literal notranslate"><span class="pre">0xef</span></code>, <code class="docutils literal notranslate"><span class="pre">0xbb</span></code>, <code class="docutils literal notranslate"><span class="pre">0xbf</span></code>) is written. As it’s rather improbable that any charmap encoded file starts with these byte values (which would e.g. map to</p> <blockquote> <div><div class="line-block"> <div class="line">LATIN SMALL LETTER I WITH DIAERESIS</div> <div class="line">RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK</div> <div class="line">INVERTED QUESTION MARK</div> </div> </div></blockquote> <p>in iso-8859-1), this increases the probability that a <code class="docutils literal notranslate"><span class="pre">utf-8-sig</span></code> encoding can be correctly guessed from the byte sequence. So here the BOM is not used to be able to determine the byte order used for generating the byte sequence, but as a signature that helps in guessing the encoding. On encoding the utf-8-sig codec will write <code class="docutils literal notranslate"><span class="pre">0xef</span></code>, <code class="docutils literal notranslate"><span class="pre">0xbb</span></code>, <code class="docutils literal notranslate"><span class="pre">0xbf</span></code> as the first three bytes to the file. On decoding <code class="docutils literal notranslate"><span class="pre">utf-8-sig</span></code> will skip those three bytes if they appear as the first three bytes in the file. In UTF-8, the use of the BOM is discouraged and should generally be avoided.</p> </div> <div class="section" id="standard-encodings"> <span id="id3"></span><h2>7.2.3. Standard Encodings<a class="headerlink" href="#standard-encodings" title="Permalink to this headline">¶</a></h2> <p>Python comes with a number of codecs built-in, either implemented as C functions or with dictionaries as mapping tables. The following table lists the codecs by name, together with a few common aliases, and the languages for which the encoding is likely used. Neither the list of aliases nor the list of languages is meant to be exhaustive. Notice that spelling alternatives that only differ in case or use a hyphen instead of an underscore are also valid aliases; therefore, e.g. <code class="docutils literal notranslate"><span class="pre">'utf-8'</span></code> is a valid alias for the <code class="docutils literal notranslate"><span class="pre">'utf_8'</span></code> codec.</p> <div class="impl-detail compound"> <p class="compound-first"><strong>CPython implementation detail:</strong> Some common encodings can bypass the codecs lookup machinery to improve performance. These optimization opportunities are only recognized by CPython for a limited set of (case insensitive) aliases: utf-8, utf8, latin-1, latin1, iso-8859-1, iso8859-1, mbcs (Windows only), ascii, us-ascii, utf-16, utf16, utf-32, utf32, and the same using underscores instead of dashes. Using alternative aliases for these encodings may result in slower execution.</p> <div class="compound-last versionchanged"> <p><span class="versionmodified">Changed in version 3.6: </span>Optimization opportunity recognized for us-ascii.</p> </div> </div> <p>Many of the character sets support the same languages. They vary in individual characters (e.g. whether the EURO SIGN is supported or not), and in the assignment of characters to code positions. For the European languages in particular, the following variants typically exist:</p> <ul class="simple"> <li>an ISO 8859 codeset</li> <li>a Microsoft Windows code page, which is typically derived from an 8859 codeset, but replaces control characters with additional graphic characters</li> <li>an IBM EBCDIC code page</li> <li>an IBM PC code page, which is ASCII compatible</li> </ul> <table border="1" class="docutils"> <colgroup> <col width="21%" /> <col width="40%" /> <col width="40%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Codec</th> <th class="head">Aliases</th> <th class="head">Languages</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td>ascii</td> <td>646, us-ascii</td> <td>English</td> </tr> <tr class="row-odd"><td>big5</td> <td>big5-tw, csbig5</td> <td>Traditional Chinese</td> </tr> <tr class="row-even"><td>big5hkscs</td> <td>big5-hkscs, hkscs</td> <td>Traditional Chinese</td> </tr> <tr class="row-odd"><td>cp037</td> <td>IBM037, IBM039</td> <td>English</td> </tr> <tr class="row-even"><td>cp273</td> <td>273, IBM273, csIBM273</td> <td><p class="first">German</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.4.</span></p> </div> </td> </tr> <tr class="row-odd"><td>cp424</td> <td>EBCDIC-CP-HE, IBM424</td> <td>Hebrew</td> </tr> <tr class="row-even"><td>cp437</td> <td>437, IBM437</td> <td>English</td> </tr> <tr class="row-odd"><td>cp500</td> <td>EBCDIC-CP-BE, EBCDIC-CP-CH, IBM500</td> <td>Western Europe</td> </tr> <tr class="row-even"><td>cp720</td> <td> </td> <td>Arabic</td> </tr> <tr class="row-odd"><td>cp737</td> <td> </td> <td>Greek</td> </tr> <tr class="row-even"><td>cp775</td> <td>IBM775</td> <td>Baltic languages</td> </tr> <tr class="row-odd"><td>cp850</td> <td>850, IBM850</td> <td>Western Europe</td> </tr> <tr class="row-even"><td>cp852</td> <td>852, IBM852</td> <td>Central and Eastern Europe</td> </tr> <tr class="row-odd"><td>cp855</td> <td>855, IBM855</td> <td>Bulgarian, Byelorussian, Macedonian, Russian, Serbian</td> </tr> <tr class="row-even"><td>cp856</td> <td> </td> <td>Hebrew</td> </tr> <tr class="row-odd"><td>cp857</td> <td>857, IBM857</td> <td>Turkish</td> </tr> <tr class="row-even"><td>cp858</td> <td>858, IBM858</td> <td>Western Europe</td> </tr> <tr class="row-odd"><td>cp860</td> <td>860, IBM860</td> <td>Portuguese</td> </tr> <tr class="row-even"><td>cp861</td> <td>861, CP-IS, IBM861</td> <td>Icelandic</td> </tr> <tr class="row-odd"><td>cp862</td> <td>862, IBM862</td> <td>Hebrew</td> </tr> <tr class="row-even"><td>cp863</td> <td>863, IBM863</td> <td>Canadian</td> </tr> <tr class="row-odd"><td>cp864</td> <td>IBM864</td> <td>Arabic</td> </tr> <tr class="row-even"><td>cp865</td> <td>865, IBM865</td> <td>Danish, Norwegian</td> </tr> <tr class="row-odd"><td>cp866</td> <td>866, IBM866</td> <td>Russian</td> </tr> <tr class="row-even"><td>cp869</td> <td>869, CP-GR, IBM869</td> <td>Greek</td> </tr> <tr class="row-odd"><td>cp874</td> <td> </td> <td>Thai</td> </tr> <tr class="row-even"><td>cp875</td> <td> </td> <td>Greek</td> </tr> <tr class="row-odd"><td>cp932</td> <td>932, ms932, mskanji, ms-kanji</td> <td>Japanese</td> </tr> <tr class="row-even"><td>cp949</td> <td>949, ms949, uhc</td> <td>Korean</td> </tr> <tr class="row-odd"><td>cp950</td> <td>950, ms950</td> <td>Traditional Chinese</td> </tr> <tr class="row-even"><td>cp1006</td> <td> </td> <td>Urdu</td> </tr> <tr class="row-odd"><td>cp1026</td> <td>ibm1026</td> <td>Turkish</td> </tr> <tr class="row-even"><td>cp1125</td> <td>1125, ibm1125, cp866u, ruscii</td> <td><p class="first">Ukrainian</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.4.</span></p> </div> </td> </tr> <tr class="row-odd"><td>cp1140</td> <td>ibm1140</td> <td>Western Europe</td> </tr> <tr class="row-even"><td>cp1250</td> <td>windows-1250</td> <td>Central and Eastern Europe</td> </tr> <tr class="row-odd"><td>cp1251</td> <td>windows-1251</td> <td>Bulgarian, Byelorussian, Macedonian, Russian, Serbian</td> </tr> <tr class="row-even"><td>cp1252</td> <td>windows-1252</td> <td>Western Europe</td> </tr> <tr class="row-odd"><td>cp1253</td> <td>windows-1253</td> <td>Greek</td> </tr> <tr class="row-even"><td>cp1254</td> <td>windows-1254</td> <td>Turkish</td> </tr> <tr class="row-odd"><td>cp1255</td> <td>windows-1255</td> <td>Hebrew</td> </tr> <tr class="row-even"><td>cp1256</td> <td>windows-1256</td> <td>Arabic</td> </tr> <tr class="row-odd"><td>cp1257</td> <td>windows-1257</td> <td>Baltic languages</td> </tr> <tr class="row-even"><td>cp1258</td> <td>windows-1258</td> <td>Vietnamese</td> </tr> <tr class="row-odd"><td>cp65001</td> <td> </td> <td><p class="first">Windows only: Windows UTF-8 (<code class="docutils literal notranslate"><span class="pre">CP_UTF8</span></code>)</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.3.</span></p> </div> </td> </tr> <tr class="row-even"><td>euc_jp</td> <td>eucjp, ujis, u-jis</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>euc_jis_2004</td> <td>jisx0213, eucjis2004</td> <td>Japanese</td> </tr> <tr class="row-even"><td>euc_jisx0213</td> <td>eucjisx0213</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>euc_kr</td> <td>euckr, korean, ksc5601, ks_c-5601, ks_c-5601-1987, ksx1001, ks_x-1001</td> <td>Korean</td> </tr> <tr class="row-even"><td>gb2312</td> <td>chinese, csiso58gb231280, euc- cn, euccn, eucgb2312-cn, gb2312-1980, gb2312-80, iso- ir-58</td> <td>Simplified Chinese</td> </tr> <tr class="row-odd"><td>gbk</td> <td>936, cp936, ms936</td> <td>Unified Chinese</td> </tr> <tr class="row-even"><td>gb18030</td> <td>gb18030-2000</td> <td>Unified Chinese</td> </tr> <tr class="row-odd"><td>hz</td> <td>hzgb, hz-gb, hz-gb-2312</td> <td>Simplified Chinese</td> </tr> <tr class="row-even"><td>iso2022_jp</td> <td>csiso2022jp, iso2022jp, iso-2022-jp</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>iso2022_jp_1</td> <td>iso2022jp-1, iso-2022-jp-1</td> <td>Japanese</td> </tr> <tr class="row-even"><td>iso2022_jp_2</td> <td>iso2022jp-2, iso-2022-jp-2</td> <td>Japanese, Korean, Simplified Chinese, Western Europe, Greek</td> </tr> <tr class="row-odd"><td>iso2022_jp_2004</td> <td>iso2022jp-2004, iso-2022-jp-2004</td> <td>Japanese</td> </tr> <tr class="row-even"><td>iso2022_jp_3</td> <td>iso2022jp-3, iso-2022-jp-3</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>iso2022_jp_ext</td> <td>iso2022jp-ext, iso-2022-jp-ext</td> <td>Japanese</td> </tr> <tr class="row-even"><td>iso2022_kr</td> <td>csiso2022kr, iso2022kr, iso-2022-kr</td> <td>Korean</td> </tr> <tr class="row-odd"><td>latin_1</td> <td>iso-8859-1, iso8859-1, 8859, cp819, latin, latin1, L1</td> <td>West Europe</td> </tr> <tr class="row-even"><td>iso8859_2</td> <td>iso-8859-2, latin2, L2</td> <td>Central and Eastern Europe</td> </tr> <tr class="row-odd"><td>iso8859_3</td> <td>iso-8859-3, latin3, L3</td> <td>Esperanto, Maltese</td> </tr> <tr class="row-even"><td>iso8859_4</td> <td>iso-8859-4, latin4, L4</td> <td>Baltic languages</td> </tr> <tr class="row-odd"><td>iso8859_5</td> <td>iso-8859-5, cyrillic</td> <td>Bulgarian, Byelorussian, Macedonian, Russian, Serbian</td> </tr> <tr class="row-even"><td>iso8859_6</td> <td>iso-8859-6, arabic</td> <td>Arabic</td> </tr> <tr class="row-odd"><td>iso8859_7</td> <td>iso-8859-7, greek, greek8</td> <td>Greek</td> </tr> <tr class="row-even"><td>iso8859_8</td> <td>iso-8859-8, hebrew</td> <td>Hebrew</td> </tr> <tr class="row-odd"><td>iso8859_9</td> <td>iso-8859-9, latin5, L5</td> <td>Turkish</td> </tr> <tr class="row-even"><td>iso8859_10</td> <td>iso-8859-10, latin6, L6</td> <td>Nordic languages</td> </tr> <tr class="row-odd"><td>iso8859_11</td> <td>iso-8859-11, thai</td> <td>Thai languages</td> </tr> <tr class="row-even"><td>iso8859_13</td> <td>iso-8859-13, latin7, L7</td> <td>Baltic languages</td> </tr> <tr class="row-odd"><td>iso8859_14</td> <td>iso-8859-14, latin8, L8</td> <td>Celtic languages</td> </tr> <tr class="row-even"><td>iso8859_15</td> <td>iso-8859-15, latin9, L9</td> <td>Western Europe</td> </tr> <tr class="row-odd"><td>iso8859_16</td> <td>iso-8859-16, latin10, L10</td> <td>South-Eastern Europe</td> </tr> <tr class="row-even"><td>johab</td> <td>cp1361, ms1361</td> <td>Korean</td> </tr> <tr class="row-odd"><td>koi8_r</td> <td> </td> <td>Russian</td> </tr> <tr class="row-even"><td>koi8_t</td> <td> </td> <td><p class="first">Tajik</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.5.</span></p> </div> </td> </tr> <tr class="row-odd"><td>koi8_u</td> <td> </td> <td>Ukrainian</td> </tr> <tr class="row-even"><td>kz1048</td> <td>kz_1048, strk1048_2002, rk1048</td> <td><p class="first">Kazakh</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.5.</span></p> </div> </td> </tr> <tr class="row-odd"><td>mac_cyrillic</td> <td>maccyrillic</td> <td>Bulgarian, Byelorussian, Macedonian, Russian, Serbian</td> </tr> <tr class="row-even"><td>mac_greek</td> <td>macgreek</td> <td>Greek</td> </tr> <tr class="row-odd"><td>mac_iceland</td> <td>maciceland</td> <td>Icelandic</td> </tr> <tr class="row-even"><td>mac_latin2</td> <td>maclatin2, maccentraleurope</td> <td>Central and Eastern Europe</td> </tr> <tr class="row-odd"><td>mac_roman</td> <td>macroman, macintosh</td> <td>Western Europe</td> </tr> <tr class="row-even"><td>mac_turkish</td> <td>macturkish</td> <td>Turkish</td> </tr> <tr class="row-odd"><td>ptcp154</td> <td>csptcp154, pt154, cp154, cyrillic-asian</td> <td>Kazakh</td> </tr> <tr class="row-even"><td>shift_jis</td> <td>csshiftjis, shiftjis, sjis, s_jis</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>shift_jis_2004</td> <td>shiftjis2004, sjis_2004, sjis2004</td> <td>Japanese</td> </tr> <tr class="row-even"><td>shift_jisx0213</td> <td>shiftjisx0213, sjisx0213, s_jisx0213</td> <td>Japanese</td> </tr> <tr class="row-odd"><td>utf_32</td> <td>U32, utf32</td> <td>all languages</td> </tr> <tr class="row-even"><td>utf_32_be</td> <td>UTF-32BE</td> <td>all languages</td> </tr> <tr class="row-odd"><td>utf_32_le</td> <td>UTF-32LE</td> <td>all languages</td> </tr> <tr class="row-even"><td>utf_16</td> <td>U16, utf16</td> <td>all languages</td> </tr> <tr class="row-odd"><td>utf_16_be</td> <td>UTF-16BE</td> <td>all languages</td> </tr> <tr class="row-even"><td>utf_16_le</td> <td>UTF-16LE</td> <td>all languages</td> </tr> <tr class="row-odd"><td>utf_7</td> <td>U7, unicode-1-1-utf-7</td> <td>all languages</td> </tr> <tr class="row-even"><td>utf_8</td> <td>U8, UTF, utf8</td> <td>all languages</td> </tr> <tr class="row-odd"><td>utf_8_sig</td> <td> </td> <td>all languages</td> </tr> </tbody> </table> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.4: </span>The utf-16* and utf-32* encoders no longer allow surrogate code points (<code class="docutils literal notranslate"><span class="pre">U+D800</span></code>–<code class="docutils literal notranslate"><span class="pre">U+DFFF</span></code>) to be encoded. The utf-32* decoders no longer decode byte sequences that correspond to surrogate code points.</p> </div> </div> <div class="section" id="python-specific-encodings"> <h2>7.2.4. Python Specific Encodings<a class="headerlink" href="#python-specific-encodings" title="Permalink to this headline">¶</a></h2> <p>A number of predefined codecs are specific to Python, so their codec names have no meaning outside Python. These are listed in the tables below based on the expected input and output types (note that while text encodings are the most common use case for codecs, the underlying codec infrastructure supports arbitrary data transforms rather than just text encodings). For asymmetric codecs, the stated purpose describes the encoding direction.</p> <div class="section" id="text-encodings"> <h3>7.2.4.1. Text Encodings<a class="headerlink" href="#text-encodings" title="Permalink to this headline">¶</a></h3> <p>The following codecs provide <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> to <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> encoding and <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> to <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> decoding, similar to the Unicode text encodings.</p> <table border="1" class="docutils"> <colgroup> <col width="36%" /> <col width="16%" /> <col width="48%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Codec</th> <th class="head">Aliases</th> <th class="head">Purpose</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td>idna</td> <td> </td> <td>Implements <span class="target" id="index-3"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3490.html"><strong>RFC 3490</strong></a>, see also <a class="reference internal" href="#module-encodings.idna" title="encodings.idna: Internationalized Domain Names implementation"><code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.idna</span></code></a>. Only <code class="docutils literal notranslate"><span class="pre">errors='strict'</span></code> is supported.</td> </tr> <tr class="row-odd"><td>mbcs</td> <td>ansi, dbcs</td> <td>Windows only: Encode operand according to the ANSI codepage (CP_ACP)</td> </tr> <tr class="row-even"><td>oem</td> <td> </td> <td><p class="first">Windows only: Encode operand according to the OEM codepage (CP_OEMCP)</p> <div class="last versionadded"> <p><span class="versionmodified">New in version 3.6.</span></p> </div> </td> </tr> <tr class="row-odd"><td>palmos</td> <td> </td> <td>Encoding of PalmOS 3.5</td> </tr> <tr class="row-even"><td>punycode</td> <td> </td> <td>Implements <span class="target" id="index-4"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3492.html"><strong>RFC 3492</strong></a>. Stateful codecs are not supported.</td> </tr> <tr class="row-odd"><td>raw_unicode_escape</td> <td> </td> <td>Latin-1 encoding with <code class="docutils literal notranslate"><span class="pre">\uXXXX</span></code> and <code class="docutils literal notranslate"><span class="pre">\UXXXXXXXX</span></code> for other code points. Existing backslashes are not escaped in any way. It is used in the Python pickle protocol.</td> </tr> <tr class="row-even"><td>undefined</td> <td> </td> <td>Raise an exception for all conversions, even empty strings. The error handler is ignored.</td> </tr> <tr class="row-odd"><td>unicode_escape</td> <td> </td> <td>Encoding suitable as the contents of a Unicode literal in ASCII-encoded Python source code, except that quotes are not escaped. Decodes from Latin-1 source code. Beware that Python source code actually uses UTF-8 by default.</td> </tr> <tr class="row-even"><td>unicode_internal</td> <td> </td> <td><p class="first">Return the internal representation of the operand. Stateful codecs are not supported.</p> <div class="last deprecated"> <p><span class="versionmodified">Deprecated since version 3.3: </span>This representation is obsoleted by <span class="target" id="index-5"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0393"><strong>PEP 393</strong></a>.</p> </div> </td> </tr> </tbody> </table> </div> <div class="section" id="binary-transforms"> <span id="id4"></span><h3>7.2.4.2. Binary Transforms<a class="headerlink" href="#binary-transforms" title="Permalink to this headline">¶</a></h3> <p>The following codecs provide binary transforms: <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> to <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> mappings. They are not supported by <a class="reference internal" href="stdtypes.html#bytes.decode" title="bytes.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">bytes.decode()</span></code></a> (which only produces <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> output).</p> <table border="1" class="docutils"> <colgroup> <col width="22%" /> <col width="18%" /> <col width="30%" /> <col width="30%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Codec</th> <th class="head">Aliases</th> <th class="head">Purpose</th> <th class="head">Encoder / decoder</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td>base64_codec <a class="footnote-reference" href="#b64" id="id5">[1]</a></td> <td>base64, base_64</td> <td><p class="first">Convert operand to multiline MIME base64 (the result always includes a trailing <code class="docutils literal notranslate"><span class="pre">'\n'</span></code>)</p> <div class="last versionchanged"> <p><span class="versionmodified">Changed in version 3.4: </span>accepts any <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> as input for encoding and decoding</p> </div> </td> <td><a class="reference internal" href="base64.html#base64.encodebytes" title="base64.encodebytes"><code class="xref py py-meth docutils literal notranslate"><span class="pre">base64.encodebytes()</span></code></a> / <a class="reference internal" href="base64.html#base64.decodebytes" title="base64.decodebytes"><code class="xref py py-meth docutils literal notranslate"><span class="pre">base64.decodebytes()</span></code></a></td> </tr> <tr class="row-odd"><td>bz2_codec</td> <td>bz2</td> <td>Compress the operand using bz2</td> <td><a class="reference internal" href="bz2.html#bz2.compress" title="bz2.compress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">bz2.compress()</span></code></a> / <a class="reference internal" href="bz2.html#bz2.decompress" title="bz2.decompress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">bz2.decompress()</span></code></a></td> </tr> <tr class="row-even"><td>hex_codec</td> <td>hex</td> <td>Convert operand to hexadecimal representation, with two digits per byte</td> <td><a class="reference internal" href="binascii.html#binascii.b2a_hex" title="binascii.b2a_hex"><code class="xref py py-meth docutils literal notranslate"><span class="pre">binascii.b2a_hex()</span></code></a> / <a class="reference internal" href="binascii.html#binascii.a2b_hex" title="binascii.a2b_hex"><code class="xref py py-meth docutils literal notranslate"><span class="pre">binascii.a2b_hex()</span></code></a></td> </tr> <tr class="row-odd"><td>quopri_codec</td> <td>quopri, quotedprintable, quoted_printable</td> <td>Convert operand to MIME quoted printable</td> <td><a class="reference internal" href="quopri.html#quopri.encode" title="quopri.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">quopri.encode()</span></code></a> with <code class="docutils literal notranslate"><span class="pre">quotetabs=True</span></code> / <a class="reference internal" href="quopri.html#quopri.decode" title="quopri.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">quopri.decode()</span></code></a></td> </tr> <tr class="row-even"><td>uu_codec</td> <td>uu</td> <td>Convert the operand using uuencode</td> <td><a class="reference internal" href="uu.html#uu.encode" title="uu.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">uu.encode()</span></code></a> / <a class="reference internal" href="uu.html#uu.decode" title="uu.decode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">uu.decode()</span></code></a></td> </tr> <tr class="row-odd"><td>zlib_codec</td> <td>zip, zlib</td> <td>Compress the operand using gzip</td> <td><a class="reference internal" href="zlib.html#zlib.compress" title="zlib.compress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">zlib.compress()</span></code></a> / <a class="reference internal" href="zlib.html#zlib.decompress" title="zlib.decompress"><code class="xref py py-meth docutils literal notranslate"><span class="pre">zlib.decompress()</span></code></a></td> </tr> </tbody> </table> <table class="docutils footnote" frame="void" id="b64" rules="none"> <colgroup><col class="label" /><col /></colgroup> <tbody valign="top"> <tr><td class="label"><a class="fn-backref" href="#id5">[1]</a></td><td>In addition to <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like objects</span></a>, <code class="docutils literal notranslate"><span class="pre">'base64_codec'</span></code> also accepts ASCII-only instances of <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> for decoding</td></tr> </tbody> </table> <div class="versionadded"> <p><span class="versionmodified">New in version 3.2: </span>Restoration of the binary transforms.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.4: </span>Restoration of the aliases for the binary transforms.</p> </div> </div> <div class="section" id="text-transforms"> <span id="id6"></span><h3>7.2.4.3. Text Transforms<a class="headerlink" href="#text-transforms" title="Permalink to this headline">¶</a></h3> <p>The following codec provides a text transform: a <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> to <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> mapping. It is not supported by <a class="reference internal" href="stdtypes.html#str.encode" title="str.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">str.encode()</span></code></a> (which only produces <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> output).</p> <table border="1" class="docutils"> <colgroup> <col width="36%" /> <col width="16%" /> <col width="48%" /> </colgroup> <thead valign="bottom"> <tr class="row-odd"><th class="head">Codec</th> <th class="head">Aliases</th> <th class="head">Purpose</th> </tr> </thead> <tbody valign="top"> <tr class="row-even"><td>rot_13</td> <td>rot13</td> <td>Returns the Caesar-cypher encryption of the operand</td> </tr> </tbody> </table> <div class="versionadded"> <p><span class="versionmodified">New in version 3.2: </span>Restoration of the <code class="docutils literal notranslate"><span class="pre">rot_13</span></code> text transform.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.4: </span>Restoration of the <code class="docutils literal notranslate"><span class="pre">rot13</span></code> alias.</p> </div> </div> </div> <div class="section" id="module-encodings.idna"> <span id="encodings-idna-internationalized-domain-names-in-applications"></span><h2>7.2.5. <a class="reference internal" href="#module-encodings.idna" title="encodings.idna: Internationalized Domain Names implementation"><code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.idna</span></code></a> — Internationalized Domain Names in Applications<a class="headerlink" href="#module-encodings.idna" title="Permalink to this headline">¶</a></h2> <p>This module implements <span class="target" id="index-6"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3490.html"><strong>RFC 3490</strong></a> (Internationalized Domain Names in Applications) and <span class="target" id="index-7"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3492.html"><strong>RFC 3492</strong></a> (Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)). It builds upon the <code class="docutils literal notranslate"><span class="pre">punycode</span></code> encoding and <a class="reference internal" href="stringprep.html#module-stringprep" title="stringprep: String preparation, as per RFC 3453"><code class="xref py py-mod docutils literal notranslate"><span class="pre">stringprep</span></code></a>.</p> <p>These RFCs together define a protocol to support non-ASCII characters in domain names. A domain name containing non-ASCII characters (such as <code class="docutils literal notranslate"><span class="pre">www.Alliancefrançaise.nu</span></code>) is converted into an ASCII-compatible encoding (ACE, such as <code class="docutils literal notranslate"><span class="pre">www.xn--alliancefranaise-npb.nu</span></code>). The ACE form of the domain name is then used in all places where arbitrary characters are not allowed by the protocol, such as DNS queries, HTTP <em class="mailheader">Host</em> fields, and so on. This conversion is carried out in the application; if possible invisible to the user: The application should transparently convert Unicode domain labels to IDNA on the wire, and convert back ACE labels to Unicode before presenting them to the user.</p> <p>Python supports this conversion in several ways: the <code class="docutils literal notranslate"><span class="pre">idna</span></code> codec performs conversion between Unicode and ACE, separating an input string into labels based on the separator characters defined in <span class="target" id="index-8"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3490.html#section-3.1"><strong>section 3.1 of RFC 3490</strong></a> and converting each label to ACE as required, and conversely separating an input byte string into labels based on the <code class="docutils literal notranslate"><span class="pre">.</span></code> separator and converting any ACE labels found into unicode. Furthermore, the <a class="reference internal" href="socket.html#module-socket" title="socket: Low-level networking interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">socket</span></code></a> module transparently converts Unicode host names to ACE, so that applications need not be concerned about converting host names themselves when they pass them to the socket module. On top of that, modules that have host names as function parameters, such as <a class="reference internal" href="http.client.html#module-http.client" title="http.client: HTTP and HTTPS protocol client (requires sockets)."><code class="xref py py-mod docutils literal notranslate"><span class="pre">http.client</span></code></a> and <a class="reference internal" href="ftplib.html#module-ftplib" title="ftplib: FTP protocol client (requires sockets)."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ftplib</span></code></a>, accept Unicode host names (<a class="reference internal" href="http.client.html#module-http.client" title="http.client: HTTP and HTTPS protocol client (requires sockets)."><code class="xref py py-mod docutils literal notranslate"><span class="pre">http.client</span></code></a> then also transparently sends an IDNA hostname in the <em class="mailheader">Host</em> field if it sends that field at all).</p> <p>When receiving host names from the wire (such as in reverse name lookup), no automatic conversion to Unicode is performed: Applications wishing to present such host names to the user should decode them to Unicode.</p> <p>The module <a class="reference internal" href="#module-encodings.idna" title="encodings.idna: Internationalized Domain Names implementation"><code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.idna</span></code></a> also implements the nameprep procedure, which performs certain normalizations on host names, to achieve case-insensitivity of international domain names, and to unify similar characters. The nameprep functions can be used directly if desired.</p> <dl class="function"> <dt id="encodings.idna.nameprep"> <code class="descclassname">encodings.idna.</code><code class="descname">nameprep</code><span class="sig-paren">(</span><em>label</em><span class="sig-paren">)</span><a class="headerlink" href="#encodings.idna.nameprep" title="Permalink to this definition">¶</a></dt> <dd><p>Return the nameprepped version of <em>label</em>. The implementation currently assumes query strings, so <code class="docutils literal notranslate"><span class="pre">AllowUnassigned</span></code> is true.</p> </dd></dl> <dl class="function"> <dt id="encodings.idna.ToASCII"> <code class="descclassname">encodings.idna.</code><code class="descname">ToASCII</code><span class="sig-paren">(</span><em>label</em><span class="sig-paren">)</span><a class="headerlink" href="#encodings.idna.ToASCII" title="Permalink to this definition">¶</a></dt> <dd><p>Convert a label to ASCII, as specified in <span class="target" id="index-9"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3490.html"><strong>RFC 3490</strong></a>. <code class="docutils literal notranslate"><span class="pre">UseSTD3ASCIIRules</span></code> is assumed to be false.</p> </dd></dl> <dl class="function"> <dt id="encodings.idna.ToUnicode"> <code class="descclassname">encodings.idna.</code><code class="descname">ToUnicode</code><span class="sig-paren">(</span><em>label</em><span class="sig-paren">)</span><a class="headerlink" href="#encodings.idna.ToUnicode" title="Permalink to this definition">¶</a></dt> <dd><p>Convert a label to Unicode, as specified in <span class="target" id="index-10"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc3490.html"><strong>RFC 3490</strong></a>.</p> </dd></dl> </div> <div class="section" id="module-encodings.mbcs"> <span id="encodings-mbcs-windows-ansi-codepage"></span><h2>7.2.6. <a class="reference internal" href="#module-encodings.mbcs" title="encodings.mbcs: Windows ANSI codepage"><code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.mbcs</span></code></a> — Windows ANSI codepage<a class="headerlink" href="#module-encodings.mbcs" title="Permalink to this headline">¶</a></h2> <p>Encode operand according to the ANSI codepage (CP_ACP).</p> <p>Availability: Windows only.</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.3: </span>Support any error handler.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 3.2: </span>Before 3.2, the <em>errors</em> argument was ignored; <code class="docutils literal notranslate"><span class="pre">'replace'</span></code> was always used to encode, and <code class="docutils literal notranslate"><span class="pre">'ignore'</span></code> to decode.</p> </div> </div> <div class="section" id="module-encodings.utf_8_sig"> <span id="encodings-utf-8-sig-utf-8-codec-with-bom-signature"></span><h2>7.2.7. <a class="reference internal" href="#module-encodings.utf_8_sig" title="encodings.utf_8_sig: UTF-8 codec with BOM signature"><code class="xref py py-mod docutils literal notranslate"><span class="pre">encodings.utf_8_sig</span></code></a> — UTF-8 codec with BOM signature<a class="headerlink" href="#module-encodings.utf_8_sig" title="Permalink to this headline">¶</a></h2> <p>This module implements a variant of the UTF-8 codec: On encoding a UTF-8 encoded BOM will be prepended to the UTF-8 encoded bytes. For the stateful encoder this is only done once (on the first write to the byte stream). For decoding an optional UTF-8 encoded BOM at the start of the data will be skipped.</p> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">7.2. <code class="docutils literal notranslate"><span class="pre">codecs</span></code> — Codec registry and base classes</a><ul> <li><a class="reference internal" href="#codec-base-classes">7.2.1. Codec Base Classes</a><ul> <li><a class="reference internal" href="#error-handlers">7.2.1.1. Error Handlers</a></li> <li><a class="reference internal" href="#stateless-encoding-and-decoding">7.2.1.2. Stateless Encoding and Decoding</a></li> <li><a class="reference internal" href="#incremental-encoding-and-decoding">7.2.1.3. Incremental Encoding and Decoding</a><ul> <li><a class="reference internal" href="#incrementalencoder-objects">7.2.1.3.1. IncrementalEncoder Objects</a></li> <li><a class="reference internal" href="#incrementaldecoder-objects">7.2.1.3.2. IncrementalDecoder Objects</a></li> </ul> </li> <li><a class="reference internal" href="#stream-encoding-and-decoding">7.2.1.4. Stream Encoding and Decoding</a><ul> <li><a class="reference internal" href="#streamwriter-objects">7.2.1.4.1. StreamWriter Objects</a></li> <li><a class="reference internal" href="#streamreader-objects">7.2.1.4.2. StreamReader Objects</a></li> <li><a class="reference internal" href="#streamreaderwriter-objects">7.2.1.4.3. StreamReaderWriter Objects</a></li> <li><a class="reference internal" href="#streamrecoder-objects">7.2.1.4.4. StreamRecoder Objects</a></li> </ul> </li> </ul> </li> <li><a class="reference internal" href="#encodings-and-unicode">7.2.2. Encodings and Unicode</a></li> <li><a class="reference internal" href="#standard-encodings">7.2.3. Standard Encodings</a></li> <li><a class="reference internal" href="#python-specific-encodings">7.2.4. Python Specific Encodings</a><ul> <li><a class="reference internal" href="#text-encodings">7.2.4.1. Text Encodings</a></li> <li><a class="reference internal" href="#binary-transforms">7.2.4.2. Binary Transforms</a></li> <li><a class="reference internal" href="#text-transforms">7.2.4.3. Text Transforms</a></li> </ul> </li> <li><a class="reference internal" href="#module-encodings.idna">7.2.5. <code class="docutils literal notranslate"><span class="pre">encodings.idna</span></code> — Internationalized Domain Names in Applications</a></li> <li><a class="reference internal" href="#module-encodings.mbcs">7.2.6. <code class="docutils literal notranslate"><span class="pre">encodings.mbcs</span></code> — Windows ANSI codepage</a></li> <li><a class="reference internal" href="#module-encodings.utf_8_sig">7.2.7. <code class="docutils literal notranslate"><span class="pre">encodings.utf_8_sig</span></code> — UTF-8 codec with BOM signature</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="struct.html" title="previous chapter">7.1. <code class="docutils literal notranslate"><span class="pre">struct</span></code> — Interpret bytes as packed binary data</a></p> <h4>Next topic</h4> <p class="topless"><a href="datatypes.html" title="next chapter">8. Data Types</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.6/Doc/library/codecs.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <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="datatypes.html" title="8. 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