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<div class="section" id="support-for-qsettings">
<h1>Support for <a class="reference internal" href="api/qsettings.html#PyQt5.QtCore.QSettings" title="PyQt5.QtCore.QSettings"><tt class="xref py py-class docutils literal"><span class="pre">QSettings</span></tt></a><a class="headerlink" href="#support-for-qsettings" title="Permalink to this headline">ΒΆ</a></h1>
<p>Qt provies the <a class="reference internal" href="api/qsettings.html#PyQt5.QtCore.QSettings" title="PyQt5.QtCore.QSettings"><tt class="xref py py-class docutils literal"><span class="pre">QSettings</span></tt></a> class as a platform independent
API for the persistent storage and retrieval of application settings. Settings
are retrieved using the <tt class="xref py py-meth docutils literal"><span class="pre">value()</span></tt> method. However
the type of the value returned may not be what is expected. Some platforms
only ever store string values which means that the type of the original value
is lost. Therefore a setting with an integer value of <tt class="docutils literal"><span class="pre">42</span></tt> may be retrieved
(on some platforms) as a string value of <tt class="docutils literal"><span class="pre">'42'</span></tt>.</p>
<p>As a solution to this problem PyQt5’s implementation of
<tt class="xref py py-meth docutils literal"><span class="pre">value()</span></tt> takes an optional third argument called
<tt class="docutils literal"><span class="pre">type</span></tt>. This is either a Python type object, e.g. <tt class="docutils literal"><span class="pre">int</span></tt>, or a string that
is the name of a C++ type, e.g. <tt class="docutils literal"><span class="pre">'QStringList'</span></tt>. The value returned will be
an object of the requested type.</p>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">PyQt5.QtCore</span> <span class="kn">import</span> <span class="n">QSettings</span><span class="p">,</span> <span class="n">QPoint</span>
<span class="n">settings</span> <span class="o">=</span> <span class="n">QSettings</span><span class="p">(</span><span class="s">'foo'</span><span class="p">,</span> <span class="s">'foo'</span><span class="p">)</span>
<span class="n">settings</span><span class="o">.</span><span class="n">setValue</span><span class="p">(</span><span class="s">'int_value'</span><span class="p">,</span> <span class="mi">42</span><span class="p">)</span>
<span class="n">settings</span><span class="o">.</span><span class="n">setValue</span><span class="p">(</span><span class="s">'point_value'</span><span class="p">,</span> <span class="n">QPoint</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span> <span class="mi">12</span><span class="p">))</span>
<span class="c"># This will write the setting to the platform specific storage.</span>
<span class="k">del</span> <span class="n">settings</span>
<span class="n">settings</span> <span class="o">=</span> <span class="n">QSettings</span><span class="p">(</span><span class="s">'foo'</span><span class="p">,</span> <span class="s">'foo'</span><span class="p">)</span>
<span class="n">int_value</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">value</span><span class="p">(</span><span class="s">'int_value'</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="nb">int</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s">"int_value: </span><span class="si">%s</span><span class="s">"</span> <span class="o">%</span> <span class="nb">repr</span><span class="p">(</span><span class="n">int_value</span><span class="p">))</span>
<span class="n">point_value</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">value</span><span class="p">(</span><span class="s">'point_value'</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="n">QPoint</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s">"point_value: </span><span class="si">%s</span><span class="s">"</span> <span class="o">%</span> <span class="nb">repr</span><span class="p">(</span><span class="n">point_value</span><span class="p">))</span>
</pre></div>
</div>
<p>When this is executed then the following will be displayed for all platforms:</p>
<div class="highlight-python"><pre>int_value: 42
point_value: PyQt5.QtCore.QPoint(10, 20)</pre>
</div>
<p>If the value of the setting is a container (corresponding to either
<tt class="docutils literal"><span class="pre">QVariantList</span></tt>, <tt class="docutils literal"><span class="pre">QVariantMap</span></tt> or <tt class="docutils literal"><span class="pre">QVariantHash</span></tt>) then the type is applied
to the contents of the container.</p>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">PyQt5.QtCore</span> <span class="kn">import</span> <span class="n">QSettings</span>
<span class="n">settings</span> <span class="o">=</span> <span class="n">QSettings</span><span class="p">(</span><span class="s">'foo'</span><span class="p">,</span> <span class="s">'foo'</span><span class="p">)</span>
<span class="n">settings</span><span class="o">.</span><span class="n">setValue</span><span class="p">(</span><span class="s">'list_value'</span><span class="p">,</span> <span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">])</span>
<span class="n">settings</span><span class="o">.</span><span class="n">setValue</span><span class="p">(</span><span class="s">'dict_value'</span><span class="p">,</span> <span class="p">{</span><span class="s">'one'</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span> <span class="s">'two'</span><span class="p">:</span> <span class="mi">2</span><span class="p">})</span>
<span class="c"># This will write the setting to the platform specific storage.</span>
<span class="k">del</span> <span class="n">settings</span>
<span class="n">settings</span> <span class="o">=</span> <span class="n">QSettings</span><span class="p">(</span><span class="s">'foo'</span><span class="p">,</span> <span class="s">'foo'</span><span class="p">)</span>
<span class="n">list_value</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">value</span><span class="p">(</span><span class="s">'list_value'</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="nb">int</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s">"list_value: </span><span class="si">%s</span><span class="s">"</span> <span class="o">%</span> <span class="nb">repr</span><span class="p">(</span><span class="n">list_value</span><span class="p">))</span>
<span class="n">dict_value</span> <span class="o">=</span> <span class="n">settings</span><span class="o">.</span><span class="n">value</span><span class="p">(</span><span class="s">'dict_value'</span><span class="p">,</span> <span class="nb">type</span><span class="o">=</span><span class="nb">int</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="s">"dict_value: </span><span class="si">%s</span><span class="s">"</span> <span class="o">%</span> <span class="nb">repr</span><span class="p">(</span><span class="n">dict_value</span><span class="p">))</span>
</pre></div>
</div>
<p>When this is executed then the following will be displayed for all platforms:</p>
<div class="highlight-python"><pre>list_value: [1, 2, 3]
dict_value: {'one': 1, 'two': 2}</pre>
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