qtsingleapplication/doc/html/qtsinglecoreapplication-example-console.html


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<?xml version="1.0" encoding="iso-8859-1"?>
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  <title>A non-GUI example</title>
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</tr></table><h1 class="title">A non-GUI example<br /><span class="subtitle"></span>
</h1>
<p>This example shows how to use the single-application functionality in a console application. It does not require the <tt>QtGui</tt> library at all.</p>
<p>The only differences from the GUI application usage demonstrated in the other examples are:</p>
<p>1) The <tt>.pro</tt> file should include <tt>qtsinglecoreapplication.pri</tt> instead of <tt>qtsingleapplication.pri</tt></p>
<p>2) The class name is <tt>QtSingleCoreApplication</tt> instead of <tt>QtSingleApplication</tt>.</p>
<p>3) No calls are made regarding window activation, for obvious reasons.</p>
<p>console.pro:</p>
<pre> TEMPLATE   = app
 CONFIG    += console
 SOURCES   += main.cpp
 include(../../src/qtsinglecoreapplication.pri)
 QT -= gui</pre>
<p>main.cpp:</p>
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 #include &quot;qtsinglecoreapplication.h&quot;
 #include &lt;QtCore/QDebug&gt;

 void report(const QString&amp; msg)
 {
     qDebug(&quot;[%i] %s&quot;, (int)QCoreApplication::applicationPid(), qPrintable(msg));
 }

 class MainClass : public QObject
 {
     Q_OBJECT
 public:
     MainClass()
         : QObject()
         {}

 public slots:
     void handleMessage(const QString&amp; message)
         {
             report( &quot;Message received: \&quot;&quot; + message + &quot;\&quot;&quot;);
         }
 };

 int main(int argc, char **argv)
 {
     report(&quot;Starting up&quot;);

     QtSingleCoreApplication app(argc, argv);

     if (app.isRunning()) {
         QString msg(QString(&quot;Hi master, I am %1.&quot;).arg(QCoreApplication::applicationPid()));
         bool sentok = app.sendMessage(msg, 2000);
         QString rep(&quot;Another instance is running, so I will exit.&quot;);
         rep += sentok ? &quot; Message sent ok.&quot; : &quot; Message sending failed; the other instance may be frozen.&quot;;
         report(rep);
         return 0;
     } else {
         report(&quot;No other instance is running; so I will.&quot;);
         MainClass mainObj;
         QObject::connect(&amp;app, SIGNAL(messageReceived(const QString&amp;)),
                          &amp;mainObj, SLOT(handleMessage(const QString&amp;)));
         return app.exec();
     }
 }

 #include &quot;main.moc&quot;</pre>
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