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<div class="section" id="module-future_builtins">
<h1>28.3. <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>
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