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<div class="section" id="module-future_builtins">
<span id="future-builtins-python-3-builtins"></span><h1>28.4. <a class="reference internal" href="#module-future_builtins" title="future_builtins"><code class="xref py py-mod docutils literal notranslate"><span class="pre">future_builtins</span></code></a> — Python 3 builtins<a class="headerlink" href="#module-future_builtins" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
<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-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">future_builtins</span> <span class="k">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-2to3"><span class="xref std std-term">2to3</span></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="admonition-title">Note</p>
<p>The Python 3 <a class="reference internal" href="functions.html#print" title="print"><code class="xref py py-func docutils literal notranslate"><span class="pre">print()</span></code></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="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">__future__</span> <span class="k">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">
<code class="descclassname">future_builtins.</code><code class="descname">ascii</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><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="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a>. In Python 3, <a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> will return
printable Unicode characters unescaped, while <a class="reference internal" href="#future_builtins.ascii" title="future_builtins.ascii"><code class="xref py py-func docutils literal notranslate"><span class="pre">ascii()</span></code></a> will always
backslash-escape them. Using <a class="reference internal" href="#future_builtins.ascii" title="future_builtins.ascii"><code class="xref py py-func docutils literal notranslate"><span class="pre">future_builtins.ascii()</span></code></a> instead of
<a class="reference internal" href="functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></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">
<code class="descclassname">future_builtins.</code><code class="descname">filter</code><span class="sig-paren">(</span><em>function</em>, <em>iterable</em><span class="sig-paren">)</span><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"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.ifilter()</span></code></a>.</p>
</dd></dl>
<dl class="function">
<dt id="future_builtins.hex">
<code class="descclassname">future_builtins.</code><code class="descname">hex</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><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"><code class="xref py py-func docutils literal notranslate"><span class="pre">hex()</span></code></a>, but instead of <a class="reference internal" href="../reference/datamodel.html#object.__hex__" title="object.__hex__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hex__()</span></code></a> it will
use the <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></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">
<code class="descclassname">future_builtins.</code><code class="descname">map</code><span class="sig-paren">(</span><em>function</em>, <em>iterable</em>, <em>...</em><span class="sig-paren">)</span><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"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.imap()</span></code></a>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>In Python 3, <a class="reference internal" href="functions.html#map" title="map"><code class="xref py py-func docutils literal notranslate"><span class="pre">map()</span></code></a> does not accept <code class="docutils literal notranslate"><span class="pre">None</span></code> for the
function argument.</p>
</div>
</dd></dl>
<dl class="function">
<dt id="future_builtins.oct">
<code class="descclassname">future_builtins.</code><code class="descname">oct</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><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"><code class="xref py py-func docutils literal notranslate"><span class="pre">oct()</span></code></a>, but instead of <a class="reference internal" href="../reference/datamodel.html#object.__oct__" title="object.__oct__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__oct__()</span></code></a> it will
use the <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></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">
<code class="descclassname">future_builtins.</code><code class="descname">zip</code><span class="sig-paren">(</span><em>*iterables</em><span class="sig-paren">)</span><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"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.izip()</span></code></a>.</p>
</dd></dl>
</div>
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