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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>19.1.12. email.charset: Representing character sets — 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="19.1.13. email.encoders: Encoders" href="email.encoders.html" /> <link rel="prev" title="19.1.11. email.header: Internationalized headers" href="email.header.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/email.charset.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="email.encoders.html" title="19.1.13. email.encoders: Encoders" accesskey="N">next</a> |</li> <li class="right" > <a href="email.header.html" title="19.1.11. email.header: Internationalized headers" 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="netdata.html" >19. Internet Data Handling</a> »</li> <li class="nav-item nav-item-3"><a href="email.html" accesskey="U">19.1. <code class="docutils literal notranslate"><span class="pre">email</span></code> — An email and MIME handling package</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-email.charset"> <span id="email-charset-representing-character-sets"></span><h1>19.1.12. <a class="reference internal" href="#module-email.charset" title="email.charset: Character Sets"><code class="xref py py-mod docutils literal notranslate"><span class="pre">email.charset</span></code></a>: Representing character sets<a class="headerlink" href="#module-email.charset" 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/email/charset.py">Lib/email/charset.py</a></p> <hr class="docutils" /> <p>This module is part of the legacy (<code class="docutils literal notranslate"><span class="pre">Compat32</span></code>) email API. In the new API only the aliases table is used.</p> <p>The remaining text in this section is the original documentation of the module.</p> <p>This module provides a class <a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> for representing character sets and character set conversions in email messages, as well as a character set registry and several convenience methods for manipulating this registry. Instances of <a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> are used in several other modules within the <a class="reference internal" href="email.html#module-email" title="email: Package supporting the parsing, manipulating, and generating email messages."><code class="xref py py-mod docutils literal notranslate"><span class="pre">email</span></code></a> package.</p> <p>Import this class from the <a class="reference internal" href="#module-email.charset" title="email.charset: Character Sets"><code class="xref py py-mod docutils literal notranslate"><span class="pre">email.charset</span></code></a> module.</p> <dl class="class"> <dt id="email.charset.Charset"> <em class="property">class </em><code class="descclassname">email.charset.</code><code class="descname">Charset</code><span class="sig-paren">(</span><em>input_charset=DEFAULT_CHARSET</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset" title="Permalink to this definition">¶</a></dt> <dd><p>Map character sets to their email properties.</p> <p>This class provides information about the requirements imposed on email for a specific character set. It also provides convenience routines for converting between character sets, given the availability of the applicable codecs. Given a character set, it will do its best to provide information on how to use that character set in an email message in an RFC-compliant way.</p> <p>Certain character sets must be encoded with quoted-printable or base64 when used in email headers or bodies. Certain character sets must be converted outright, and are not allowed in email.</p> <p>Optional <em>input_charset</em> is as described below; it is always coerced to lower case. After being alias normalized it is also used as a lookup into the registry of character sets to find out the header encoding, body encoding, and output conversion codec to be used for the character set. For example, if <em>input_charset</em> is <code class="docutils literal notranslate"><span class="pre">iso-8859-1</span></code>, then headers and bodies will be encoded using quoted-printable and no output conversion codec is necessary. If <em>input_charset</em> is <code class="docutils literal notranslate"><span class="pre">euc-jp</span></code>, then headers will be encoded with base64, bodies will not be encoded, but output text will be converted from the <code class="docutils literal notranslate"><span class="pre">euc-jp</span></code> character set to the <code class="docutils literal notranslate"><span class="pre">iso-2022-jp</span></code> character set.</p> <p><a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> instances have the following data attributes:</p> <dl class="attribute"> <dt id="email.charset.Charset.input_charset"> <code class="descname">input_charset</code><a class="headerlink" href="#email.charset.Charset.input_charset" title="Permalink to this definition">¶</a></dt> <dd><p>The initial character set specified. Common aliases are converted to their <em>official</em> email names (e.g. <code class="docutils literal notranslate"><span class="pre">latin_1</span></code> is converted to <code class="docutils literal notranslate"><span class="pre">iso-8859-1</span></code>). Defaults to 7-bit <code class="docutils literal notranslate"><span class="pre">us-ascii</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="email.charset.Charset.header_encoding"> <code class="descname">header_encoding</code><a class="headerlink" href="#email.charset.Charset.header_encoding" title="Permalink to this definition">¶</a></dt> <dd><p>If the character set must be encoded before it can be used in an email header, this attribute will be set to <code class="docutils literal notranslate"><span class="pre">Charset.QP</span></code> (for quoted-printable), <code class="docutils literal notranslate"><span class="pre">Charset.BASE64</span></code> (for base64 encoding), or <code class="docutils literal notranslate"><span class="pre">Charset.SHORTEST</span></code> for the shortest of QP or BASE64 encoding. Otherwise, it will be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="email.charset.Charset.body_encoding"> <code class="descname">body_encoding</code><a class="headerlink" href="#email.charset.Charset.body_encoding" title="Permalink to this definition">¶</a></dt> <dd><p>Same as <em>header_encoding</em>, but describes the encoding for the mail message’s body, which indeed may be different than the header encoding. <code class="docutils literal notranslate"><span class="pre">Charset.SHORTEST</span></code> is not allowed for <em>body_encoding</em>.</p> </dd></dl> <dl class="attribute"> <dt id="email.charset.Charset.output_charset"> <code class="descname">output_charset</code><a class="headerlink" href="#email.charset.Charset.output_charset" title="Permalink to this definition">¶</a></dt> <dd><p>Some character sets must be converted before they can be used in email headers or bodies. If the <em>input_charset</em> is one of them, this attribute will contain the name of the character set output will be converted to. Otherwise, it will be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="email.charset.Charset.input_codec"> <code class="descname">input_codec</code><a class="headerlink" href="#email.charset.Charset.input_codec" title="Permalink to this definition">¶</a></dt> <dd><p>The name of the Python codec used to convert the <em>input_charset</em> to Unicode. If no conversion codec is necessary, this attribute will be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="email.charset.Charset.output_codec"> <code class="descname">output_codec</code><a class="headerlink" href="#email.charset.Charset.output_codec" title="Permalink to this definition">¶</a></dt> <dd><p>The name of the Python codec used to convert Unicode to the <em>output_charset</em>. If no conversion codec is necessary, this attribute will have the same value as the <em>input_codec</em>.</p> </dd></dl> <p><a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> instances also have the following methods:</p> <dl class="method"> <dt id="email.charset.Charset.get_body_encoding"> <code class="descname">get_body_encoding</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.get_body_encoding" title="Permalink to this definition">¶</a></dt> <dd><p>Return the content transfer encoding used for body encoding.</p> <p>This is either the string <code class="docutils literal notranslate"><span class="pre">quoted-printable</span></code> or <code class="docutils literal notranslate"><span class="pre">base64</span></code> depending on the encoding used, or it is a function, in which case you should call the function with a single argument, the Message object being encoded. The function should then set the <em class="mailheader">Content-Transfer-Encoding</em> header itself to whatever is appropriate.</p> <p>Returns the string <code class="docutils literal notranslate"><span class="pre">quoted-printable</span></code> if <em>body_encoding</em> is <code class="docutils literal notranslate"><span class="pre">QP</span></code>, returns the string <code class="docutils literal notranslate"><span class="pre">base64</span></code> if <em>body_encoding</em> is <code class="docutils literal notranslate"><span class="pre">BASE64</span></code>, and returns the string <code class="docutils literal notranslate"><span class="pre">7bit</span></code> otherwise.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.get_output_charset"> <code class="descname">get_output_charset</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.get_output_charset" title="Permalink to this definition">¶</a></dt> <dd><p>Return the output character set.</p> <p>This is the <em>output_charset</em> attribute if that is not <code class="docutils literal notranslate"><span class="pre">None</span></code>, otherwise it is <em>input_charset</em>.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.header_encode"> <code class="descname">header_encode</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.header_encode" title="Permalink to this definition">¶</a></dt> <dd><p>Header-encode the string <em>string</em>.</p> <p>The type of encoding (base64 or quoted-printable) will be based on the <em>header_encoding</em> attribute.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.header_encode_lines"> <code class="descname">header_encode_lines</code><span class="sig-paren">(</span><em>string</em>, <em>maxlengths</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.header_encode_lines" title="Permalink to this definition">¶</a></dt> <dd><p>Header-encode a <em>string</em> by converting it first to bytes.</p> <p>This is similar to <a class="reference internal" href="#email.charset.Charset.header_encode" title="email.charset.Charset.header_encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">header_encode()</span></code></a> except that the string is fit into maximum line lengths as given by the argument <em>maxlengths</em>, which must be an iterator: each element returned from this iterator will provide the next maximum line length.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.body_encode"> <code class="descname">body_encode</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.body_encode" title="Permalink to this definition">¶</a></dt> <dd><p>Body-encode the string <em>string</em>.</p> <p>The type of encoding (base64 or quoted-printable) will be based on the <em>body_encoding</em> attribute.</p> </dd></dl> <p>The <a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> class also provides a number of methods to support standard operations and built-in functions.</p> <dl class="method"> <dt id="email.charset.Charset.__str__"> <code class="descname">__str__</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.__str__" title="Permalink to this definition">¶</a></dt> <dd><p>Returns <em>input_charset</em> as a string coerced to lower case. <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__repr__()</span></code></a> is an alias for <a class="reference internal" href="#email.charset.Charset.__str__" title="email.charset.Charset.__str__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__str__()</span></code></a>.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.__eq__"> <code class="descname">__eq__</code><span class="sig-paren">(</span><em>other</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.__eq__" title="Permalink to this definition">¶</a></dt> <dd><p>This method allows you to compare two <a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> instances for equality.</p> </dd></dl> <dl class="method"> <dt id="email.charset.Charset.__ne__"> <code class="descname">__ne__</code><span class="sig-paren">(</span><em>other</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.Charset.__ne__" title="Permalink to this definition">¶</a></dt> <dd><p>This method allows you to compare two <a class="reference internal" href="#email.charset.Charset" title="email.charset.Charset"><code class="xref py py-class docutils literal notranslate"><span class="pre">Charset</span></code></a> instances for inequality.</p> </dd></dl> </dd></dl> <p>The <a class="reference internal" href="#module-email.charset" title="email.charset: Character Sets"><code class="xref py py-mod docutils literal notranslate"><span class="pre">email.charset</span></code></a> module also provides the following functions for adding new entries to the global character set, alias, and codec registries:</p> <dl class="function"> <dt id="email.charset.add_charset"> <code class="descclassname">email.charset.</code><code class="descname">add_charset</code><span class="sig-paren">(</span><em>charset</em>, <em>header_enc=None</em>, <em>body_enc=None</em>, <em>output_charset=None</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.add_charset" title="Permalink to this definition">¶</a></dt> <dd><p>Add character properties to the global registry.</p> <p><em>charset</em> is the input character set, and must be the canonical name of a character set.</p> <p>Optional <em>header_enc</em> and <em>body_enc</em> is either <code class="docutils literal notranslate"><span class="pre">Charset.QP</span></code> for quoted-printable, <code class="docutils literal notranslate"><span class="pre">Charset.BASE64</span></code> for base64 encoding, <code class="docutils literal notranslate"><span class="pre">Charset.SHORTEST</span></code> for the shortest of quoted-printable or base64 encoding, or <code class="docutils literal notranslate"><span class="pre">None</span></code> for no encoding. <code class="docutils literal notranslate"><span class="pre">SHORTEST</span></code> is only valid for <em>header_enc</em>. The default is <code class="docutils literal notranslate"><span class="pre">None</span></code> for no encoding.</p> <p>Optional <em>output_charset</em> is the character set that the output should be in. Conversions will proceed from input charset, to Unicode, to the output charset when the method <code class="xref py py-meth docutils literal notranslate"><span class="pre">Charset.convert()</span></code> is called. The default is to output in the same character set as the input.</p> <p>Both <em>input_charset</em> and <em>output_charset</em> must have Unicode codec entries in the module’s character set-to-codec mapping; use <a class="reference internal" href="#email.charset.add_codec" title="email.charset.add_codec"><code class="xref py py-func docutils literal notranslate"><span class="pre">add_codec()</span></code></a> to add codecs the module does not know about. See the <a class="reference internal" href="codecs.html#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’s documentation for more information.</p> <p>The global character set registry is kept in the module global dictionary <code class="docutils literal notranslate"><span class="pre">CHARSETS</span></code>.</p> </dd></dl> <dl class="function"> <dt id="email.charset.add_alias"> <code class="descclassname">email.charset.</code><code class="descname">add_alias</code><span class="sig-paren">(</span><em>alias</em>, <em>canonical</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.add_alias" title="Permalink to this definition">¶</a></dt> <dd><p>Add a character set alias. <em>alias</em> is the alias name, e.g. <code class="docutils literal notranslate"><span class="pre">latin-1</span></code>. <em>canonical</em> is the character set’s canonical name, e.g. <code class="docutils literal notranslate"><span class="pre">iso-8859-1</span></code>.</p> <p>The global charset alias registry is kept in the module global dictionary <code class="docutils literal notranslate"><span class="pre">ALIASES</span></code>.</p> </dd></dl> <dl class="function"> <dt id="email.charset.add_codec"> <code class="descclassname">email.charset.</code><code class="descname">add_codec</code><span class="sig-paren">(</span><em>charset</em>, <em>codecname</em><span class="sig-paren">)</span><a class="headerlink" href="#email.charset.add_codec" title="Permalink to this definition">¶</a></dt> <dd><p>Add a codec that map characters in the given character set to and from Unicode.</p> <p><em>charset</em> is the canonical name of a character set. <em>codecname</em> is the name of a Python codec, as appropriate for the second argument to the <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>’s <a class="reference internal" href="stdtypes.html#str.encode" title="str.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">encode()</span></code></a> method.</p> </dd></dl> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="email.header.html" title="previous chapter">19.1.11. <code class="docutils literal notranslate"><span class="pre">email.header</span></code>: Internationalized headers</a></p> <h4>Next topic</h4> <p class="topless"><a href="email.encoders.html" title="next chapter">19.1.13. <code class="docutils literal notranslate"><span class="pre">email.encoders</span></code>: Encoders</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/email.charset.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="email.encoders.html" title="19.1.13. email.encoders: Encoders" >next</a> |</li> <li class="right" > <a href="email.header.html" title="19.1.11. email.header: Internationalized headers" >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="netdata.html" >19. Internet Data Handling</a> »</li> <li class="nav-item nav-item-3"><a href="email.html" >19.1. <code class="docutils literal notranslate"><span class="pre">email</span></code> — An email and MIME handling package</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="footer"> © <a href="../copyright.html">Copyright</a> 2001-2021, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Aug 25, 2021. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.6. </div> </body> </html>