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<li class="toctree-l1 current"><a class="current reference internal" href="">Overview: Easy, clean, reliable Python 2/3 compatibility</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="imports.html#external-standard-library-backports">External standard-library backports</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#included-full-backports">Included full backports</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#using-python-2-only-dependencies-on-python-3">Using Python 2-only dependencies on Python 3</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#should-i-import-unicode-literals">Should I import unicode_literals?</a><ul>
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<li class="toctree-l3"><a class="reference internal" href="imports.html#others-perspectives">Others&#8217; perspectives</a></li>
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<li class="toctree-l2"><a class="reference internal" href="imports.html#next-steps">Next steps</a></li>
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<li class="toctree-l1"><a class="reference internal" href="what_else.html">What else you need to know</a><ul>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#bytes">bytes</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#str">str</a></li>
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<li class="toctree-l3"><a class="reference internal" href="what_else.html#memory-efficiency-and-alternatives">Memory-efficiency and alternatives</a></li>
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<li class="toctree-l2"><a class="reference internal" href="what_else.html#int">int</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#isinstance">isinstance</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#passing-data-to-from-python-2-libraries">Passing data to/from Python 2 libraries</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#native-string-type">Native string type</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#open">open()</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#custom-str-methods">Custom __str__ methods</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#custom-iterators">Custom iterators</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#binding-a-method-to-a-class">Binding a method to a class</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#metaclasses">Metaclasses</a></li>
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<li class="toctree-l1"><a class="reference internal" href="automatic_conversion.html">Automatic conversion to Py2/3</a><ul>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#futurize-py2-to-py2-3"><code class="docutils literal"><span class="pre">futurize</span></code>: Py2 to Py2/3</a><ul>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#stage-1-safe-fixes">Stage 1: &#8220;safe&#8221; fixes</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#stage-2-py3-style-code-with-wrappers-for-py2">Stage 2: Py3-style code with wrappers for Py2</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#separating-text-from-bytes">Separating text from bytes</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#post-conversion">Post-conversion</a></li>
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<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#futurize-quick-start-guide"><code class="docutils literal"><span class="pre">futurize</span></code> quick-start guide</a><ul>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-0-setup">Step 0: setup</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-1-modern-py2-code">Step 1: modern Py2 code</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-2-working-py3-code-that-still-supports-py2">Step 2: working Py3 code that still supports Py2</a></li>
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<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#pasteurize-py3-to-py2-3"><code class="docutils literal"><span class="pre">pasteurize</span></code>: Py3 to Py2/3</a></li>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#known-limitations">Known limitations</a></li>
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<li class="toctree-l1"><a class="reference internal" href="faq.html">Frequently Asked Questions (FAQ)</a><ul>
<li class="toctree-l2"><a class="reference internal" href="faq.html#who-is-this-for">Who is this for?</a></li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#why-upgrade-to-python-3">Why upgrade to Python 3?</a></li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#porting-philosophy">Porting philosophy</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#why-write-python-3-style-code">Why write Python 3-style code?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#can-t-i-just-roll-my-own-py2-3-compatibility-layer">Can&#8217;t I just roll my own Py2/3 compatibility layer?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#what-inspired-this-project">What inspired this project?</a></li>
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<li class="toctree-l2"><a class="reference internal" href="faq.html#maturity">Maturity</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#how-well-has-it-been-tested">How well has it been tested?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#is-the-api-stable">Is the API stable?</a></li>
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<li class="toctree-l2"><a class="reference internal" href="faq.html#relationship-between-python-future-and-other-compatibility-tools">Relationship between python-future and other compatibility tools</a><ul>
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  <div class="section" id="overview-easy-clean-reliable-python-2-3-compatibility">
<span id="overview"></span><h1>Overview: Easy, clean, reliable Python 2/3 compatibility<a class="headerlink" href="#overview-easy-clean-reliable-python-2-3-compatibility" title="Permalink to this headline">¶</a></h1>
<p><code class="docutils literal"><span class="pre">python-future</span></code> is the missing compatibility layer between Python 2 and
Python 3. It allows you to use a single, clean Python 3.x-compatible
codebase to support both Python 2 and Python 3 with minimal overhead.</p>
<p>It provides <code class="docutils literal"><span class="pre">future</span></code> and <code class="docutils literal"><span class="pre">past</span></code> packages with backports and forward
ports of features from Python 3 and 2. It also comes with <code class="docutils literal"><span class="pre">futurize</span></code> and
<code class="docutils literal"><span class="pre">pasteurize</span></code>, customized 2to3-based scripts that helps you to convert
either Py2 or Py3 code easily to support both Python 2 and 3 in a single
clean Py3-style codebase, module by module.</p>
<p>Notable projects that use <code class="docutils literal"><span class="pre">python-future</span></code> for Python 2/3 compatibility
are <a class="reference external" href="http://mezzanine.jupo.org/">Mezzanine</a> and <a class="reference external" href="http://obspy.org">ObsPy</a>.</p>
<div class="section" id="features">
<span id="id1"></span><h2>Features<a class="headerlink" href="#features" title="Permalink to this headline">¶</a></h2>
<a class="reference external image-reference" href="https://travis-ci.org/PythonCharmers/python-future"><img alt="https://travis-ci.org/PythonCharmers/python-future.svg?branch=master" src="https://travis-ci.org/PythonCharmers/python-future.svg?branch=master" /></a>
<ul class="simple">
<li><code class="docutils literal"><span class="pre">future.builtins</span></code> package (also available as <code class="docutils literal"><span class="pre">builtins</span></code> on Py2) provides
backports and remappings for 20 builtins with different semantics on Py3
versus Py2</li>
<li>support for directly importing 30 standard library modules under
their Python 3 names on Py2</li>
<li>support for importing the other 14 refactored standard library modules
under their Py3 names relatively cleanly via
<code class="docutils literal"><span class="pre">future.standard_library</span></code> and <code class="docutils literal"><span class="pre">future.moves</span></code></li>
<li><code class="docutils literal"><span class="pre">past.builtins</span></code> package provides forward-ports of 19 Python 2 types and
builtin functions. These can aid with per-module code migrations.</li>
<li><code class="docutils literal"><span class="pre">past.translation</span></code> package supports transparent translation of Python 2
modules to Python 3 upon import. [This feature is currently in alpha.]</li>
<li>920+ unit tests, including many from the Py3.3 source tree.</li>
<li><code class="docutils literal"><span class="pre">futurize</span></code> and <code class="docutils literal"><span class="pre">pasteurize</span></code> scripts based on <code class="docutils literal"><span class="pre">2to3</span></code> and parts of
<code class="docutils literal"><span class="pre">3to2</span></code> and <code class="docutils literal"><span class="pre">python-modernize</span></code>, for automatic conversion from either Py2
or Py3 to a clean single-source codebase compatible with Python 2.6+ and
Python 3.3+.</li>
<li>a curated set of utility functions and decorators in <code class="docutils literal"><span class="pre">future.utils</span></code> and
<code class="docutils literal"><span class="pre">past.utils</span></code> selected from Py2/3 compatibility interfaces from projects
like <code class="docutils literal"><span class="pre">six</span></code>, <code class="docutils literal"><span class="pre">IPython</span></code>, <code class="docutils literal"><span class="pre">Jinja2</span></code>, <code class="docutils literal"><span class="pre">Django</span></code>, and <code class="docutils literal"><span class="pre">Pandas</span></code>.</li>
<li>support for the <code class="docutils literal"><span class="pre">surrogateescape</span></code> error handler when encoding and
decoding the backported <code class="docutils literal"><span class="pre">str</span></code> and <code class="docutils literal"><span class="pre">bytes</span></code> objects. [This feature is
currently in alpha.]</li>
</ul>
</div>
<div class="section" id="code-examples">
<span id="id2"></span><h2>Code examples<a class="headerlink" href="#code-examples" title="Permalink to this headline">¶</a></h2>
<p>Replacements for Py2&#8217;s built-in functions and types are designed to be imported
at the top of each Python module together with Python&#8217;s built-in <code class="docutils literal"><span class="pre">__future__</span></code>
statements. For example, this code behaves identically on Python 2.6/2.7 after
these imports as it does on Python 3.3+:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">absolute_import</span><span class="p">,</span> <span class="n">division</span><span class="p">,</span> <span class="n">print_function</span>
<span class="kn">from</span> <span class="nn">builtins</span> <span class="kn">import</span> <span class="p">(</span><span class="nb">bytes</span><span class="p">,</span> <span class="nb">str</span><span class="p">,</span> <span class="nb">open</span><span class="p">,</span> <span class="nb">super</span><span class="p">,</span> <span class="nb">range</span><span class="p">,</span>
                      <span class="nb">zip</span><span class="p">,</span> <span class="nb">round</span><span class="p">,</span> <span class="nb">input</span><span class="p">,</span> <span class="nb">int</span><span class="p">,</span> <span class="nb">pow</span><span class="p">,</span> <span class="nb">object</span><span class="p">)</span>

<span class="c"># Backported Py3 bytes object</span>
<span class="n">b</span> <span class="o">=</span> <span class="nb">bytes</span><span class="p">(</span><span class="n">b</span><span class="s">&#39;ABCD&#39;</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">list</span><span class="p">(</span><span class="n">b</span><span class="p">)</span> <span class="o">==</span> <span class="p">[</span><span class="mi">65</span><span class="p">,</span> <span class="mi">66</span><span class="p">,</span> <span class="mi">67</span><span class="p">,</span> <span class="mi">68</span><span class="p">]</span>
<span class="k">assert</span> <span class="nb">repr</span><span class="p">(</span><span class="n">b</span><span class="p">)</span> <span class="o">==</span> <span class="s">&quot;b&#39;ABCD&#39;&quot;</span>
<span class="c"># These raise TypeErrors:</span>
<span class="c"># b + u&#39;EFGH&#39;</span>
<span class="c"># bytes(b&#39;,&#39;).join([u&#39;Fred&#39;, u&#39;Bill&#39;])</span>

<span class="c"># Backported Py3 str object</span>
<span class="n">s</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="s">u&#39;ABCD&#39;</span><span class="p">)</span>
<span class="k">assert</span> <span class="n">s</span> <span class="o">!=</span> <span class="nb">bytes</span><span class="p">(</span><span class="n">b</span><span class="s">&#39;ABCD&#39;</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">s</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s">&#39;utf-8&#39;</span><span class="p">),</span> <span class="nb">bytes</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">b</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s">&#39;utf-8&#39;</span><span class="p">),</span> <span class="nb">str</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">repr</span><span class="p">(</span><span class="n">s</span><span class="p">)</span> <span class="o">==</span> <span class="s">&quot;&#39;ABCD&#39;&quot;</span>      <span class="c"># consistent repr with Py3 (no u prefix)</span>
<span class="c"># These raise TypeErrors:</span>
<span class="c"># bytes(b&#39;B&#39;) in s</span>
<span class="c"># s.find(bytes(b&#39;A&#39;))</span>

<span class="c"># Extra arguments for the open() function</span>
<span class="n">f</span> <span class="o">=</span> <span class="nb">open</span><span class="p">(</span><span class="s">&#39;japanese.txt&#39;</span><span class="p">,</span> <span class="n">encoding</span><span class="o">=</span><span class="s">&#39;utf-8&#39;</span><span class="p">,</span> <span class="n">errors</span><span class="o">=</span><span class="s">&#39;replace&#39;</span><span class="p">)</span>

<span class="c"># New zero-argument super() function:</span>
<span class="k">class</span> <span class="nc">VerboseList</span><span class="p">(</span><span class="nb">list</span><span class="p">):</span>
    <span class="k">def</span> <span class="nf">append</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">item</span><span class="p">):</span>
        <span class="k">print</span><span class="p">(</span><span class="s">&#39;Adding an item&#39;</span><span class="p">)</span>
        <span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">item</span><span class="p">)</span>

<span class="c"># New iterable range object with slicing support</span>
<span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">10</span><span class="o">**</span><span class="mi">15</span><span class="p">)[:</span><span class="mi">10</span><span class="p">]:</span>
    <span class="k">pass</span>

<span class="c"># Other iterators: map, zip, filter</span>
<span class="n">my_iter</span> <span class="o">=</span> <span class="nb">zip</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">3</span><span class="p">),</span> <span class="p">[</span><span class="s">&#39;a&#39;</span><span class="p">,</span> <span class="s">&#39;b&#39;</span><span class="p">,</span> <span class="s">&#39;c&#39;</span><span class="p">])</span>
<span class="k">assert</span> <span class="n">my_iter</span> <span class="o">!=</span> <span class="nb">list</span><span class="p">(</span><span class="n">my_iter</span><span class="p">)</span>

<span class="c"># The round() function behaves as it does in Python 3, using</span>
<span class="c"># &quot;Banker&#39;s Rounding&quot; to the nearest even last digit:</span>
<span class="k">assert</span> <span class="nb">round</span><span class="p">(</span><span class="mf">0.1250</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span> <span class="o">==</span> <span class="mf">0.12</span>

<span class="c"># input() replaces Py2&#39;s raw_input() (with no eval()):</span>
<span class="n">name</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">&#39;What is your name? &#39;</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s">&#39;Hello &#39;</span> <span class="o">+</span> <span class="n">name</span><span class="p">)</span>

<span class="c"># pow() supports fractional exponents of negative numbers like in Py3:</span>
<span class="n">z</span> <span class="o">=</span> <span class="nb">pow</span><span class="p">(</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">)</span>

<span class="c"># Compatible output from isinstance() across Py2/3:</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="mi">2</span><span class="o">**</span><span class="mi">64</span><span class="p">,</span> <span class="nb">int</span><span class="p">)</span>        <span class="c"># long integers</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="s">u&#39;blah&#39;</span><span class="p">,</span> <span class="nb">str</span><span class="p">)</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="s">&#39;blah&#39;</span><span class="p">,</span> <span class="nb">str</span><span class="p">)</span>       <span class="c"># only if unicode_literals is in effect</span>

<span class="c"># Py3-style iterators written as new-style classes (subclasses of</span>
<span class="c"># future.types.newobject) are automatically backward compatible with Py2:</span>
<span class="k">class</span> <span class="nc">Upper</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">iterable</span><span class="p">):</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">_iter</span> <span class="o">=</span> <span class="nb">iter</span><span class="p">(</span><span class="n">iterable</span><span class="p">)</span>
    <span class="k">def</span> <span class="nf">__next__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>                 <span class="c"># note the Py3 interface</span>
        <span class="k">return</span> <span class="nb">next</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_iter</span><span class="p">)</span><span class="o">.</span><span class="n">upper</span><span class="p">()</span>
    <span class="k">def</span> <span class="nf">__iter__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
        <span class="k">return</span> <span class="bp">self</span>
<span class="k">assert</span> <span class="nb">list</span><span class="p">(</span><span class="n">Upper</span><span class="p">(</span><span class="s">&#39;hello&#39;</span><span class="p">))</span> <span class="o">==</span> <span class="nb">list</span><span class="p">(</span><span class="s">&#39;HELLO&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>There is also support for renamed standard library modules. The recommended
interface works like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># Many Py3 module names are supported directly on both Py2.x and 3.x:</span>
<span class="kn">from</span> <span class="nn">http.client</span> <span class="kn">import</span> <span class="n">HttpConnection</span>
<span class="kn">import</span> <span class="nn">html.parser</span>
<span class="kn">import</span> <span class="nn">queue</span>
<span class="kn">import</span> <span class="nn">xmlrpc.client</span>

<span class="c"># Refactored modules with clashing names on Py2 and Py3 are supported</span>
<span class="c"># as follows:</span>
<span class="kn">from</span> <span class="nn">future</span> <span class="kn">import</span> <span class="n">standard_library</span>
<span class="n">standard_library</span><span class="o">.</span><span class="n">install_aliases</span><span class="p">()</span>

<span class="c"># Then, for example:</span>
<span class="kn">from</span> <span class="nn">itertools</span> <span class="kn">import</span> <span class="n">filterfalse</span><span class="p">,</span> <span class="n">zip_longest</span>
<span class="kn">from</span> <span class="nn">urllib.request</span> <span class="kn">import</span> <span class="n">urlopen</span>
<span class="kn">from</span> <span class="nn">collections</span> <span class="kn">import</span> <span class="n">ChainMap</span>
<span class="kn">from</span> <span class="nn">collections</span> <span class="kn">import</span> <span class="n">UserDict</span><span class="p">,</span> <span class="n">UserList</span><span class="p">,</span> <span class="n">UserString</span>
<span class="kn">from</span> <span class="nn">subprocess</span> <span class="kn">import</span> <span class="n">getoutput</span><span class="p">,</span> <span class="n">getstatusoutput</span>
<span class="kn">from</span> <span class="nn">collections</span> <span class="kn">import</span> <span class="n">Counter</span><span class="p">,</span> <span class="n">OrderedDict</span>   <span class="c"># backported to Py2.6</span>
</pre></div>
</div>
</div>
<div class="section" id="automatic-conversion-to-py2-3-compatible-code">
<h2>Automatic conversion to Py2/3-compatible code<a class="headerlink" href="#automatic-conversion-to-py2-3-compatible-code" title="Permalink to this headline">¶</a></h2>
<p><code class="docutils literal"><span class="pre">python-future</span></code> comes with two scripts called <code class="docutils literal"><span class="pre">futurize</span></code> and
<code class="docutils literal"><span class="pre">pasteurize</span></code> to aid in making Python 2 code or Python 3 code compatible with
both platforms (Py2/3). It is based on 2to3 and uses fixers from <code class="docutils literal"><span class="pre">lib2to3</span></code>,
<code class="docutils literal"><span class="pre">lib3to2</span></code>, and <code class="docutils literal"><span class="pre">python-modernize</span></code>, as well as custom fixers.</p>
<p><code class="docutils literal"><span class="pre">futurize</span></code> passes Python 2 code through all the appropriate fixers to turn it
into valid Python 3 code, and then adds <code class="docutils literal"><span class="pre">__future__</span></code> and <code class="docutils literal"><span class="pre">future</span></code> package
imports so that it also runs under Python 2.</p>
<p>For conversions from Python 3 code to Py2/3, use the <code class="docutils literal"><span class="pre">pasteurize</span></code> script
instead. This converts Py3-only constructs (e.g. new metaclass syntax) to
Py2/3 compatible constructs and adds <code class="docutils literal"><span class="pre">__future__</span></code> and <code class="docutils literal"><span class="pre">future</span></code> imports to
the top of each module.</p>
<p>In both cases, the result should be relatively clean Py3-style code that runs
mostly unchanged on both Python 2 and Python 3.</p>
<div class="section" id="futurize-2-to-both">
<h3>Futurize: 2 to both<a class="headerlink" href="#futurize-2-to-both" title="Permalink to this headline">¶</a></h3>
<p>For example, running <code class="docutils literal"><span class="pre">futurize</span> <span class="pre">-w</span> <span class="pre">mymodule.py</span></code> turns this Python 2 code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">Queue</span>
<span class="kn">from</span> <span class="nn">urllib2</span> <span class="kn">import</span> <span class="n">urlopen</span>

<span class="k">def</span> <span class="nf">greet</span><span class="p">(</span><span class="n">name</span><span class="p">):</span>
    <span class="k">print</span> <span class="s">&#39;Hello&#39;</span><span class="p">,</span>
    <span class="k">print</span> <span class="n">name</span>

<span class="k">print</span> <span class="s">&quot;What&#39;s your name?&quot;</span><span class="p">,</span>
<span class="n">name</span> <span class="o">=</span> <span class="nb">raw_input</span><span class="p">()</span>
<span class="n">greet</span><span class="p">(</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
<p>into this code which runs on both Py2 and Py3:</p>
<div class="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>
<span class="kn">from</span> <span class="nn">future</span> <span class="kn">import</span> <span class="n">standard_library</span>
<span class="n">standard_library</span><span class="o">.</span><span class="n">install_aliases</span><span class="p">()</span>
<span class="kn">from</span> <span class="nn">builtins</span> <span class="kn">import</span> <span class="nb">input</span>
<span class="kn">import</span> <span class="nn">queue</span>
<span class="kn">from</span> <span class="nn">urllib.request</span> <span class="kn">import</span> <span class="n">urlopen</span>

<span class="k">def</span> <span class="nf">greet</span><span class="p">(</span><span class="n">name</span><span class="p">):</span>
    <span class="k">print</span><span class="p">(</span><span class="s">&#39;Hello&#39;</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s">&#39; &#39;</span><span class="p">)</span>
    <span class="k">print</span><span class="p">(</span><span class="n">name</span><span class="p">)</span>

<span class="k">print</span><span class="p">(</span><span class="s">&quot;What&#39;s your name?&quot;</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s">&#39; &#39;</span><span class="p">)</span>
<span class="n">name</span> <span class="o">=</span> <span class="nb">input</span><span class="p">()</span>
<span class="n">greet</span><span class="p">(</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
<p>See <a class="reference internal" href="futurize.html#forwards-conversion"><span>futurize: Py2 to Py2/3</span></a> and <a class="reference internal" href="pasteurize.html#backwards-conversion"><span>pasteurize: Py3 to Py2/3</span></a> for more details.</p>
</div>
</div>
<div class="section" id="automatic-translation">
<h2>Automatic translation<a class="headerlink" href="#automatic-translation" title="Permalink to this headline">¶</a></h2>
<p>The <code class="docutils literal"><span class="pre">past</span></code> package can automatically translate some simple Python 2
modules to Python 3 upon import. The goal is to support the &#8220;long tail&#8221; of
real-world Python 2 modules (e.g. on PyPI) that have not been ported yet. For
example, here is how to use a Python 2-only package called <code class="docutils literal"><span class="pre">plotrique</span></code> on
Python 3. First install it:</p>
<div class="highlight-bash"><div class="highlight"><pre><span class="nv">$ </span>pip3 install <span class="nv">plotrique</span><span class="o">==</span>0.2.5-7 --no-compile   <span class="c"># to ignore SyntaxErrors</span>
</pre></div>
</div>
<p>(or use <code class="docutils literal"><span class="pre">pip</span></code> if this points to your Py3 environment.)</p>
<p>Then pass a whitelist of module name prefixes to the <code class="docutils literal"><span class="pre">autotranslate()</span></code> function.
Example:</p>
<div class="highlight-bash"><div class="highlight"><pre><span class="nv">$ </span>python3

&gt;&gt;&gt; from past import autotranslate
&gt;&gt;&gt; autotranslate<span class="o">([</span><span class="s1">&#39;plotrique&#39;</span><span class="o">])</span>
&gt;&gt;&gt; import plotrique
</pre></div>
</div>
<p>This transparently translates and runs the <code class="docutils literal"><span class="pre">plotrique</span></code> module and any
submodules in the <code class="docutils literal"><span class="pre">plotrique</span></code> package that <code class="docutils literal"><span class="pre">plotrique</span></code> imports.</p>
<p>This is intended to help you migrate to Python 3 without the need for all
your code&#8217;s dependencies to support Python 3 yet. It should be used as a
last resort; ideally Python 2-only dependencies should be ported
properly to a Python 2/3 compatible codebase using a tool like
<code class="docutils literal"><span class="pre">futurize</span></code> and the changes should be pushed to the upstream project.</p>
<p>Note: the auto-translation feature is still in alpha; it needs more testing and
development, and will likely never be perfect.</p>
<p>For more info, see <a class="reference internal" href="translation.html#translation"><span>Using Python 2-only dependencies on Python 3</span></a>.</p>
</div>
<div class="section" id="licensing">
<h2>Licensing<a class="headerlink" href="#licensing" title="Permalink to this headline">¶</a></h2>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Author:</th><td class="field-body">Ed Schofield</td>
</tr>
<tr class="field-even field"><th class="field-name">Copyright:</th><td class="field-body">2013-2015 Python Charmers Pty Ltd, Australia.</td>
</tr>
<tr class="field-odd field"><th class="field-name">Sponsor:</th><td class="field-body">Python Charmers Pty Ltd, Australia, and Python Charmers Pte
Ltd, Singapore. <a class="reference external" href="http://pythoncharmers.com">http://pythoncharmers.com</a></td>
</tr>
<tr class="field-even field"><th class="field-name">Licence:</th><td class="field-body">MIT. See <code class="docutils literal"><span class="pre">LICENSE.txt</span></code> or <a class="reference external" href="http://python-future.org/credits.html">here</a>.</td>
</tr>
<tr class="field-odd field"><th class="field-name">Other credits:</th><td class="field-body">See <a class="reference external" href="http://python-future.org/credits.html">here</a>.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="next-steps">
<h2>Next steps<a class="headerlink" href="#next-steps" title="Permalink to this headline">¶</a></h2>
<p>If you are new to Python-Future, check out the <a class="reference external" href="http://python-future.org/quickstart.html">Quickstart Guide</a>.</p>
<p>For an update on changes in the latest version, see the <a class="reference external" href="http://python-future.org/whatsnew.html">What&#8217;s New</a> page.</p>
</div>
</div>


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