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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"> <span id="future-builtins-python-3-builtins"></span><h1>27.4. <a class="reference internal" href="#module-future_builtins" title="future_builtins"><tt class="xref py py-mod docutils literal"><span class="pre">future_builtins</span></tt></a> — 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 internal" href="../glossary.html#term-to3"><em class="xref std std-term">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 class="reference internal" href="functions.html#print" title="print"><tt class="xref py py-func 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><p>Returns the same as <a class="reference internal" href="repr.html#module-repr" title="repr: Alternate repr() implementation with size limits."><tt class="xref py py-func docutils literal"><span class="pre">repr()</span></tt></a>. In Python 3, <a class="reference internal" href="repr.html#module-repr" title="repr: Alternate repr() implementation with size limits."><tt class="xref py py-func docutils literal"><span class="pre">repr()</span></tt></a> will return printable Unicode characters unescaped, while <a class="reference internal" href="#future_builtins.ascii" title="future_builtins.ascii"><tt class="xref py py-func docutils literal"><span class="pre">ascii()</span></tt></a> will always backslash-escape them. Using <a class="reference internal" href="#future_builtins.ascii" title="future_builtins.ascii"><tt class="xref py py-func docutils literal"><span class="pre">future_builtins.ascii()</span></tt></a> instead of <a class="reference internal" href="repr.html#module-repr" title="repr: Alternate repr() implementation with size limits."><tt class="xref py py-func docutils literal"><span class="pre">repr()</span></tt></a> in 2.6 code makes it clear that you need a pure ASCII return value.</p> </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><p>Works like <a class="reference internal" href="itertools.html#itertools.ifilter" title="itertools.ifilter"><tt class="xref py py-func docutils literal"><span class="pre">itertools.ifilter()</span></tt></a>.</p> </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><p>Works like the built-in <a class="reference internal" href="functions.html#hex" title="hex"><tt class="xref py py-func docutils literal"><span class="pre">hex()</span></tt></a>, but instead of <a class="reference internal" href="../reference/datamodel.html#object.__hex__" title="object.__hex__"><tt class="xref py py-meth docutils literal"><span class="pre">__hex__()</span></tt></a> it will use the <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><tt class="xref py py-meth docutils literal"><span class="pre">__index__()</span></tt></a> method on its argument to get an integer that is then converted to hexadecimal.</p> </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><p>Works like <a class="reference internal" href="itertools.html#itertools.imap" title="itertools.imap"><tt class="xref py py-func docutils literal"><span class="pre">itertools.imap()</span></tt></a>.</p> </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><p>Works like the built-in <a class="reference internal" href="functions.html#oct" title="oct"><tt class="xref py py-func docutils literal"><span class="pre">oct()</span></tt></a>, but instead of <a class="reference internal" href="../reference/datamodel.html#object.__oct__" title="object.__oct__"><tt class="xref py py-meth docutils literal"><span class="pre">__oct__()</span></tt></a> it will use the <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><tt class="xref py py-meth docutils literal"><span class="pre">__index__()</span></tt></a> method on its argument to get an integer that is then converted to octal.</p> </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><p>Works like <a class="reference internal" href="itertools.html#itertools.izip" title="itertools.izip"><tt class="xref py py-func docutils literal"><span class="pre">itertools.izip()</span></tt></a>.</p> </dd></dl> 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