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<div class="section" id="support-for-qt-properties">
<h1>Support for Qt Properties<a class="headerlink" href="#support-for-qt-properties" title="Permalink to this headline">¶</a></h1>
<p>PyQt4 does not support the setting and getting of Qt properties as if they were
normal instance attributes. This is because the name of a property often
conflicts with the name of the property’s getter method.</p>
<p>However, PyQt4 does support the initial setting of properties using keyword
arguments passed when an instance is created. For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">act</span> <span class="o">=</span> <span class="n">QtGui</span><span class="o">.</span><span class="n">QAction</span><span class="p">(</span><span class="s">"&Save"</span><span class="p">,</span> <span class="bp">self</span><span class="p">,</span> <span class="n">shortcut</span><span class="o">=</span><span class="n">QtGui</span><span class="o">.</span><span class="n">QKeySequence</span><span class="o">.</span><span class="n">Save</span><span class="p">,</span>
<span class="n">statusTip</span><span class="o">=</span><span class="s">"Save the document to disk"</span><span class="p">,</span> <span class="n">triggered</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">save</span><span class="p">)</span>
</pre></div>
</div>
<p>The example also demonstrates the use of a keyword argument to connect a
signal to a slot.</p>
<p>PyQt4 also supports setting the values of properties (and connecting a signal
to a slot) using the <code class="docutils literal"><span class="pre">pyqtConfigure()</span></code> method of <code class="docutils literal"><span class="pre">QObject</span></code>. For example,
the following gives the same results as above:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">act</span> <span class="o">=</span> <span class="n">QtGui</span><span class="o">.</span><span class="n">QAction</span><span class="p">(</span><span class="s">"&Save"</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span>
<span class="n">act</span><span class="o">.</span><span class="n">pyqtConfigure</span><span class="p">(</span><span class="n">shortcut</span><span class="o">=</span><span class="n">QtGui</span><span class="o">.</span><span class="n">QKeySequence</span><span class="o">.</span><span class="n">Save</span><span class="p">,</span>
<span class="n">statusTip</span><span class="o">=</span><span class="s">"Save the document to disk"</span><span class="p">,</span> <span class="n">triggered</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">save</span><span class="p">)</span>
</pre></div>
</div>
<div class="section" id="defining-new-qt-properties">
<h2>Defining New Qt Properties<a class="headerlink" href="#defining-new-qt-properties" title="Permalink to this headline">¶</a></h2>
<p>A new Qt property may be defined using the <a class="reference internal" href="#PyQt4.QtCore.pyqtProperty" title="PyQt4.QtCore.pyqtProperty"><code class="xref py py-func docutils literal"><span class="pre">pyqtProperty()</span></code></a>
function. It is used in the same way as the standard Python <code class="docutils literal"><span class="pre">property()</span></code>
function. In fact, Qt properties defined in this way also behave as Python
properties.</p>
<dl class="function">
<dt id="PyQt4.QtCore.pyqtProperty">
<code class="descclassname">PyQt4.QtCore.</code><code class="descname">pyqtProperty</code><span class="sig-paren">(</span><em>type</em><span class="optional">[</span>, <em>fget=None</em><span class="optional">[</span>, <em>fset=None</em><span class="optional">[</span>, <em>freset=None</em><span class="optional">[</span>, <em>fdel=None</em><span class="optional">[</span>, <em>doc=None</em><span class="optional">[</span>, <em>designable=True</em><span class="optional">[</span>, <em>scriptable=True</em><span class="optional">[</span>, <em>stored=True</em><span class="optional">[</span>, <em>user=False</em><span class="optional">[</span>, <em>constant=False</em><span class="optional">[</span>, <em>final=False</em><span class="optional">[</span>, <em>notify=None</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#PyQt4.QtCore.pyqtProperty" title="Permalink to this definition">¶</a></dt>
<dd><p>Create a property that behaves as both a Python property and a Qt property.</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"><ul class="first simple">
<li><strong>type</strong> – the type of the property. It is either a Python type object or a
string that is the name of a C++ type.</li>
<li><strong>fget</strong> – the optional callable used to get the value of the property.</li>
<li><strong>fset</strong> – the optional callable used to set the value of the property.</li>
<li><strong>freset</strong> – the optional callable used to reset the value of the property to its
default value. It is ignored by Python</li>
<li><strong>fdel</strong> – the optional callable used to delete the property. It is ignored by
Qt.</li>
<li><strong>doc</strong> – the optional docstring of the property. It is ignored by Qt.</li>
<li><strong>designable</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">DESIGNABLE</span></code> flag. It is ignored by Python</li>
<li><strong>scriptable</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">SCRIPTABLE</span></code> flag. It is ignored by Python</li>
<li><strong>stored</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">STORED</span></code> flag. It is ignored by Python</li>
<li><strong>user</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">USER</span></code> flag. It is ignored by Python</li>
<li><strong>constant</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">CONSTANT</span></code> flag. It is ignored by Python</li>
<li><strong>final</strong> – optionally sets the Qt <code class="docutils literal"><span class="pre">FINAL</span></code> flag. It is ignored by Python</li>
<li><strong>notify</strong> – the optional unbound notify signal. It is ignored by Python</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">the property object.</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>It is also possible to use <a class="reference internal" href="#PyQt4.QtCore.pyqtProperty" title="PyQt4.QtCore.pyqtProperty"><code class="xref py py-func docutils literal"><span class="pre">pyqtProperty()</span></code></a> as a decorator in
the same way as the standard Python <code class="docutils literal"><span class="pre">property()</span></code> function. The following
example shows how to define an <code class="docutils literal"><span class="pre">int</span></code> property with a getter and setter:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">PyQt4.QtCore</span> <span class="kn">import</span> <span class="n">QObject</span><span class="p">,</span> <span class="n">pyqtProperty</span>
<span class="k">class</span> <span class="nc">Foo</span><span class="p">(</span><span class="n">QObject</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">QObject</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_total</span> <span class="o">=</span> <span class="mi">0</span>
<span class="nd">@pyqtProperty</span><span class="p">(</span><span class="nb">int</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">total</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="o">.</span><span class="n">_total</span>
<span class="nd">@total.setter</span>
<span class="k">def</span> <span class="nf">total</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_total</span> <span class="o">=</span> <span class="n">value</span>
</pre></div>
</div>
<p>If you prefer the Qt terminology you may also use <code class="docutils literal"><span class="pre">write</span></code> instead of
<code class="docutils literal"><span class="pre">setter</span></code> (and <code class="docutils literal"><span class="pre">read</span></code> instead of <code class="docutils literal"><span class="pre">getter</span></code>).</p>
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<h3><a href="index.html">Table Of Contents</a></h3>
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<li><a class="reference internal" href="#">Support for Qt Properties</a><ul>
<li><a class="reference internal" href="#defining-new-qt-properties">Defining New Qt Properties</a></li>
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