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<div class="section" id="module-pkgutil">
<span id="pkgutil-package-extension-utility"></span><h1>30.5. <a class="reference internal" href="#module-pkgutil" title="Utilities to support extension of packages."><tt class="xref py py-mod docutils literal"><span class="pre">pkgutil</span></tt></a> — Package extension utility<a class="headerlink" href="#module-pkgutil" title="Permalink to this headline">¶</a></h1>
<p class="versionadded">
<span class="versionmodified">New in version 2.3.</span></p>
<p>This module provides functions to manipulate packages:</p>
<dl class="function">
<dt id="pkgutil.extend_path">
<tt class="descclassname">pkgutil.</tt><tt class="descname">extend_path</tt><big>(</big><em>path</em>, <em>name</em><big>)</big><a class="headerlink" href="#pkgutil.extend_path" title="Permalink to this definition">¶</a></dt>
<dd><p>Extend the search path for the modules which comprise a package. Intended use is
to place the following code in a package’s <tt class="file docutils literal"><span class="pre">__init__.py</span></tt>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">pkgutil</span> <span class="kn">import</span> <span class="n">extend_path</span>
<span class="n">__path__</span> <span class="o">=</span> <span class="n">extend_path</span><span class="p">(</span><span class="n">__path__</span><span class="p">,</span> <span class="n">__name__</span><span class="p">)</span>
</pre></div>
</div>
<p>This will add to the package’s <tt class="docutils literal"><span class="pre">__path__</span></tt> all subdirectories of directories on
<tt class="docutils literal"><span class="pre">sys.path</span></tt> named after the package. This is useful if one wants to distribute
different parts of a single logical package as multiple directories.</p>
<p>It also looks for <tt class="file docutils literal"><span class="pre">*.pkg</span></tt> files beginning where <tt class="docutils literal"><span class="pre">*</span></tt> matches the <em>name</em>
argument. This feature is similar to <tt class="file docutils literal"><span class="pre">*.pth</span></tt> files (see the <a class="reference internal" href="site.html#module-site" title="A standard way to reference site-specific modules."><tt class="xref py py-mod docutils literal"><span class="pre">site</span></tt></a>
module for more information), except that it doesn’t special-case lines starting
with <tt class="docutils literal"><span class="pre">import</span></tt>. A <tt class="file docutils literal"><span class="pre">*.pkg</span></tt> file is trusted at face value: apart from
checking for duplicates, all entries found in a <tt class="file docutils literal"><span class="pre">*.pkg</span></tt> file are added to
the path, regardless of whether they exist on the filesystem. (This is a
feature.)</p>
<p>If the input path is not a list (as is the case for frozen packages) it is
returned unchanged. The input path is not modified; an extended copy is
returned. Items are only appended to the copy at the end.</p>
<p>It is assumed that <tt class="docutils literal"><span class="pre">sys.path</span></tt> is a sequence. Items of <tt class="docutils literal"><span class="pre">sys.path</span></tt> that are
not (Unicode or 8-bit) strings referring to existing directories are ignored.
Unicode items on <tt class="docutils literal"><span class="pre">sys.path</span></tt> that cause errors when used as filenames may cause
this function to raise an exception (in line with <a class="reference internal" href="os.path.html#os.path.isdir" title="os.path.isdir"><tt class="xref py py-func docutils literal"><span class="pre">os.path.isdir()</span></tt></a>
behavior).</p>
</dd></dl>
<dl class="function">
<dt id="pkgutil.get_data">
<tt class="descclassname">pkgutil.</tt><tt class="descname">get_data</tt><big>(</big><em>package</em>, <em>resource</em><big>)</big><a class="headerlink" href="#pkgutil.get_data" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a resource from a package.</p>
<p>This is a wrapper for the <span class="target" id="index-0"></span><a class="pep reference external" href="http://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> loader <a class="reference internal" href="#pkgutil.get_data" title="pkgutil.get_data"><tt class="xref py py-func docutils literal"><span class="pre">get_data()</span></tt></a> API. The package
argument should be the name of a package, in standard module format
(foo.bar). The resource argument should be in the form of a relative
filename, using <tt class="docutils literal"><span class="pre">/</span></tt> as the path separator. The parent directory name
<tt class="docutils literal"><span class="pre">..</span></tt> is not allowed, and nor is a rooted name (starting with a <tt class="docutils literal"><span class="pre">/</span></tt>).</p>
<p>The function returns a binary string that is the contents of the
specified resource.</p>
<p>For packages located in the filesystem, which have already been imported,
this is the rough equivalent of:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">d</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">dirname</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">modules</span><span class="p">[</span><span class="n">package</span><span class="p">]</span><span class="o">.</span><span class="n">__file__</span><span class="p">)</span>
<span class="n">data</span> <span class="o">=</span> <span class="nb">open</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">d</span><span class="p">,</span> <span class="n">resource</span><span class="p">),</span> <span class="s">'rb'</span><span class="p">)</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
</pre></div>
</div>
<p>If the package cannot be located or loaded, or it uses a <span class="target" id="index-1"></span><a class="pep reference external" href="http://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a> loader
which does not support <a class="reference internal" href="#pkgutil.get_data" title="pkgutil.get_data"><tt class="xref py py-func docutils literal"><span class="pre">get_data()</span></tt></a>, then None is returned.</p>
</dd></dl>
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