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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>27.3. future_builtins — Python 3 builtins — Python v2.6.6 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.6.6', COLLAPSE_MODINDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python v2.6.6 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python v2.6.6 documentation" href="../index.html" /> <link rel="up" title="27. 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Python Runtime Services</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-future_builtins"> <h1>27.3. <tt class="xref docutils literal"><span class="pre">future_builtins</span></tt> — Python 3 builtins<a class="headerlink" href="#module-future_builtins" title="Permalink to this headline">¶</a></h1> <p class="versionadded"> <span class="versionmodified">New in version 2.6.</span></p> <p>This module provides functions that exist in 2.x, but have different behavior in Python 3, so they cannot be put into the 2.x builtins namespace.</p> <p>Instead, if you want to write code compatible with Python 3 builtins, import them from this module, like this:</p> <div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">future_builtins</span> <span class="kn">import</span> <span class="nb">map</span><span class="p">,</span> <span class="nb">filter</span> <span class="o">...</span> <span class="n">code</span> <span class="n">using</span> <span class="n">Python</span> <span class="mi">3</span><span class="o">-</span><span class="n">style</span> <span class="nb">map</span> <span class="ow">and</span> <span class="nb">filter</span> <span class="o">...</span> </pre></div> </div> <p>The <a class="reference external" href="../glossary.html#term-to3"><em class="xref">2to3</em></a> tool that ports Python 2 code to Python 3 will recognize this usage and leave the new builtins alone.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p>The Python 3 <a title="print" class="reference external" href="functions.html#print"><tt class="xref docutils literal"><span class="pre">print()</span></tt></a> function is already in the builtins, but cannot be accessed from Python 2 code unless you use the appropriate future statement:</p> <div class="last highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">print_function</span> </pre></div> </div> </div> <p>Available builtins are:</p> <dl class="function"> <dt id="future_builtins.ascii"> <tt class="descclassname">future_builtins.</tt><tt class="descname">ascii</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#future_builtins.ascii" title="Permalink to this definition">¶</a></dt> <dd>Returns the same as <a title="repr" class="reference external" href="functions.html#repr"><tt class="xref docutils literal"><span class="pre">repr()</span></tt></a>. In Python 3, <a title="repr" class="reference external" href="functions.html#repr"><tt class="xref docutils literal"><span class="pre">repr()</span></tt></a> will return printable Unicode characters unescaped, while <a title="future_builtins.ascii" class="reference internal" href="#future_builtins.ascii"><tt class="xref docutils literal"><span class="pre">ascii()</span></tt></a> will always backslash-escape them. Using <a title="future_builtins.ascii" class="reference internal" href="#future_builtins.ascii"><tt class="xref docutils literal"><span class="pre">future_builtins.ascii()</span></tt></a> instead of <a title="repr" class="reference external" href="functions.html#repr"><tt class="xref docutils literal"><span class="pre">repr()</span></tt></a> in 2.6 code makes it clear that you need a pure ASCII return value.</dd></dl> <dl class="function"> <dt id="future_builtins.filter"> <tt class="descclassname">future_builtins.</tt><tt class="descname">filter</tt><big>(</big><em>function</em>, <em>iterable</em><big>)</big><a class="headerlink" href="#future_builtins.filter" title="Permalink to this definition">¶</a></dt> <dd>Works like <a title="itertools.ifilter" class="reference external" href="itertools.html#itertools.ifilter"><tt class="xref docutils literal"><span class="pre">itertools.ifilter()</span></tt></a>.</dd></dl> <dl class="function"> <dt id="future_builtins.hex"> <tt class="descclassname">future_builtins.</tt><tt class="descname">hex</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#future_builtins.hex" title="Permalink to this definition">¶</a></dt> <dd>Works like the built-in <a title="hex" class="reference external" href="functions.html#hex"><tt class="xref docutils literal"><span class="pre">hex()</span></tt></a>, but instead of <a title="object.__hex__" class="reference external" href="../reference/datamodel.html#object.__hex__"><tt class="xref docutils literal"><span class="pre">__hex__()</span></tt></a> it will use the <a title="object.__index__" class="reference external" href="../reference/datamodel.html#object.__index__"><tt class="xref docutils literal"><span class="pre">__index__()</span></tt></a> method on its argument to get an integer that is then converted to hexadecimal.</dd></dl> <dl class="function"> <dt id="future_builtins.map"> <tt class="descclassname">future_builtins.</tt><tt class="descname">map</tt><big>(</big><em>function</em>, <em>iterable</em>, <em>...</em><big>)</big><a class="headerlink" href="#future_builtins.map" title="Permalink to this definition">¶</a></dt> <dd>Works like <a title="itertools.imap" class="reference external" href="itertools.html#itertools.imap"><tt class="xref docutils literal"><span class="pre">itertools.imap()</span></tt></a>.</dd></dl> <dl class="function"> <dt id="future_builtins.oct"> <tt class="descclassname">future_builtins.</tt><tt class="descname">oct</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#future_builtins.oct" title="Permalink to this definition">¶</a></dt> <dd>Works like the built-in <a title="oct" class="reference external" href="functions.html#oct"><tt class="xref docutils literal"><span class="pre">oct()</span></tt></a>, but instead of <a title="object.__oct__" class="reference external" href="../reference/datamodel.html#object.__oct__"><tt class="xref docutils literal"><span class="pre">__oct__()</span></tt></a> it will use the <a title="object.__index__" class="reference external" href="../reference/datamodel.html#object.__index__"><tt class="xref docutils literal"><span class="pre">__index__()</span></tt></a> method on its argument to get an integer that is then converted to octal.</dd></dl> <dl class="function"> <dt id="future_builtins.zip"> <tt class="descclassname">future_builtins.</tt><tt class="descname">zip</tt><big>(</big><em>*iterables</em><big>)</big><a class="headerlink" href="#future_builtins.zip" title="Permalink to this definition">¶</a></dt> <dd>Works like <a title="itertools.izip" class="reference external" href="itertools.html#itertools.izip"><tt class="xref docutils literal"><span class="pre">itertools.izip()</span></tt></a>.</dd></dl> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="__builtin__.html" title="previous chapter">27.2. <tt 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