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<div class="section" id="dbus-support">
<span id="ref-dbus"></span><h1>DBus Support<a class="headerlink" href="#dbus-support" title="Permalink to this headline">¶</a></h1>
<p>PyQt4 provides two different modules that implement support for DBus. The
<code class="xref py py-mod docutils literal"><span class="pre">QtDBus</span></code> module provides wrappers for the standard Qt DBus classes.
The <code class="xref py py-mod docutils literal"><span class="pre">dbus.mainloop.qt</span></code> module add support for the Qt event loop to the
standard <code class="docutils literal"><span class="pre">dbus-python</span></code> Python module.</p>
<div class="section" id="qtdbus">
<h2><code class="xref py py-mod docutils literal"><span class="pre">QtDBus</span></code><a class="headerlink" href="#qtdbus" title="Permalink to this headline">¶</a></h2>
<p>The <code class="xref py py-mod docutils literal"><span class="pre">QtDBus</span></code> module is used in a similar way to the C++ library it
wraps. The main difference is in the way it supports the demarshalling of
DBus structures. C++ relies on the template-based registration of types using
<code class="docutils literal"><span class="pre">qDBusRegisterMetaType()</span></code> which isn’t possible from Python. Instead a slot
that accepts a DBus structure in an argument should specify a slot with a
single <code class="xref py py-class docutils literal"><span class="pre">QDBusMessage</span></code> argument. The implementation of the
slot should then extract the arguments from the message using its
<code class="xref py py-meth docutils literal"><span class="pre">arguments()</span></code> method.</p>
<p>For example, say we have a DBus method called <code class="docutils literal"><span class="pre">setColors()</span></code> that has a single
argument that is an array of structures of three integers (red, green and
blue). The DBus signature of the argument would then be <code class="docutils literal"><span class="pre">a(iii)</span></code>. In C++
you would typically define a class to hold the red, green and blue values and
so your code would include the following (incomplete) fragments:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">struct</span> <span class="n">Color</span>
<span class="p">{</span>
<span class="nb">int</span> <span class="n">red</span><span class="p">;</span>
<span class="nb">int</span> <span class="n">green</span><span class="p">;</span>
<span class="nb">int</span> <span class="n">blue</span><span class="p">;</span>
<span class="p">};</span>
<span class="n">Q_DECLARE_METATYPE</span><span class="p">(</span><span class="n">Color</span><span class="p">)</span>
<span class="n">qDBusRegisterMetaType</span><span class="o"><</span><span class="n">Color</span><span class="o">></span><span class="p">();</span>
<span class="k">class</span> <span class="nc">ServerAdaptor</span> <span class="p">:</span> <span class="n">public</span> <span class="n">QDBusAbstractAdaptor</span>
<span class="p">{</span>
<span class="n">Q_OBJECT</span>
<span class="n">public</span> <span class="n">slots</span><span class="p">:</span>
<span class="n">void</span> <span class="n">setColors</span><span class="p">(</span><span class="n">QList</span><span class="o"><</span><span class="n">const</span> <span class="n">Color</span> <span class="o">&></span> <span class="n">colors</span><span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
<p>The Python version is, of course, much simpler:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">ServerAdaptor</span><span class="p">(</span><span class="n">QDBusAbstractAdaptor</span><span class="p">):</span>
<span class="nd">@pyqtSlot</span><span class="p">(</span><span class="n">QDBusMessage</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">setColors</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">message</span><span class="p">):</span>
<span class="c1"># Get the single argument.</span>
<span class="n">colors</span> <span class="o">=</span> <span class="n">message</span><span class="o">.</span><span class="n">arguments</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="c1"># The argument will be a list of 3-tuples of ints.</span>
<span class="k">for</span> <span class="n">red</span><span class="p">,</span> <span class="n">green</span><span class="p">,</span> <span class="n">blue</span> <span class="ow">in</span> <span class="n">colors</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"RGB:"</span><span class="p">,</span> <span class="n">red</span><span class="p">,</span> <span class="n">green</span><span class="p">,</span> <span class="n">blue</span><span class="p">)</span>
</pre></div>
</div>
<p>Note that this technique can be used for arguments of any type, it is only
require if DBus structures are involved.</p>
</div>
<div class="section" id="dbus-mainloop-qt">
<h2><code class="xref py py-mod docutils literal"><span class="pre">dbus.mainloop.qt</span></code><a class="headerlink" href="#dbus-mainloop-qt" title="Permalink to this headline">¶</a></h2>
<p>The <code class="xref py py-mod docutils literal"><span class="pre">dbus.mainloop.qt</span></code> module provides support for the Qt event loop to
<code class="docutils literal"><span class="pre">dbus-python</span></code>. The module’s API is almost identical to that of the
<code class="xref py py-mod docutils literal"><span class="pre">dbus.mainloop.glib</span></code> modules that provides support for the GLib event
loop.</p>
<p>The <code class="xref py py-mod docutils literal"><span class="pre">dbus.mainloop.qt</span></code> module contains the following function.</p>
<dl class="function">
<dt id="DBusQtMainLoop">
<code class="descname">DBusQtMainLoop</code><span class="sig-paren">(</span><em>set_as_default=False</em><span class="sig-paren">)</span><a class="headerlink" href="#DBusQtMainLoop" title="Permalink to this definition">¶</a></dt>
<dd><p>Create a <code class="docutils literal"><span class="pre">dbus.mainloop.NativeMainLoop</span></code> object that uses the the Qt event
loop.</p>
<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">Parameters:</th><td class="field-body"><strong>set_as_default</strong> – is optionally set to make the main loop instance the default for all
new Connection and Bus instances. It may only be specified as a
keyword argument, and not as a positional argument.</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>The following code fragment is all that is normally needed to set up the
standard <code class="docutils literal"><span class="pre">dbus-python</span></code> language bindings package to be used with PyQt4:</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">dbus.mainloop.qt</span> <span class="k">import</span> <span class="n">DBusQtMainLoop</span>
<span class="n">DBusQtMainLoop</span><span class="p">(</span><span class="n">set_as_default</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
</pre></div>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">DBus Support</a><ul>
<li><a class="reference internal" href="#qtdbus"><code class="docutils literal"><span class="pre">QtDBus</span></code></a></li>
<li><a class="reference internal" href="#dbus-mainloop-qt"><code class="docutils literal"><span class="pre">dbus.mainloop.qt</span></code></a></li>
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