# Source: kuniqueapp.h |
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    /* This file is part of the KDE libraries
        Copyright (c) 1999 Preston Brown <pbrown@kde.org>

        This library is free software; you can redistribute it and/or
        modify it under the terms of the GNU Library General Public
        License as published by the Free Software Foundation; either
        version 2 of the License, or (at your option) any later version.

        This library is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
        Library General Public License for more details.

        You should have received a copy of the GNU Library General Public License
        along with this library; see the file COPYING.LIB.  If not, write to
        the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
        Boston, MA 02111-1307, USA.
    */

    #ifndef _KUNIQUEAPP_H
    #define _KUNIQUEAPP_H

    #include <kapp.h>
    #include <dcopobject.h>

    class KUniqueApplicationPrivate;

    /**
     * Maintain only a single
     * instance of a running application at a time.
     *
     * If another instance
     * is started, it will determine (via DCOP) whether it is the first instance
     * or a second instance.  If it is a second instance, it will forward on
     * the information to the first instance and then quit.
     *
     * @see KApplication DCOPObject
     * @author Preston Brown <pbrown@kde.org>
     */
    class KUniqueApplication : public KApplication, public DCOPObject
    {
      Q_OBJECT
    public:
      /**
       * Constructor. Takes command line arguments from KCmdLineArgs
       * Parameters : See @ref KApplication constructor.
       */
      KUniqueApplication( bool allowStyles=true,
    		      bool GUIenabled=true);

      /**
       * Add command line options specific for KUniqueApplication
       *
       * Should be called before calling KUniqueApplication constructor
       * and / or start().
       */
      static void addCmdLineOptions();

      /**
       * Fork and register with dcop.
       *
       * The command line arguments are being sent via DCOP to @ref newInstance()
       * and will be received once the application enters the event loop.
       * @return @p true if registration is succesful.
       *         @p false if another process was already running.
       *
       * Typically this is used like:
       * <pre>
       * int main(int argc, char **argv) {
       *    KAboutData about("myappname", "myAppName", .....);
       *    KCmdLineArgs::init(argc, argv, &about);
       *    KCmdLineArgs::addCmdLineOptions( myCmdOptions );
       *    KUniqueApplication::addCmdLineOptions();
       *
       *    if (!KUniqueApplication::start()) {
       *       fprintf(stderr, "myAppName is already running!\n");
       *       exit(0);
       *    }
       *    KUniqueApplication a;
       *    a.exec();
       * }
       * </pre>
       * or
       * <pre>
       * int main(int argc, char **argv) {
       *    KAboutData about("myappname", "myAppName", .....);
       *    KCmdLineArgs::init(argc, argv, &about);
       *    KCmdLineArgs::addCmdLineOptions( myCmdOptions );
       *    KUniqueApplication::addCmdLineOptions();
       *
       *    if (!KUniqueApplication::start())
       *       exit(0);
       *    KUniqueApplication a;
       *    a.exec();
       * }
       * </pre>
       * Although it is not necassery to call @ref start() before creating a
       * @ref KUniqueApplication it is adviced to so because it is about
       * 40% faster if the application was already running:
       * If you use @ref start() the @ref KApplication constructor will not be
       * called if this isn't necessary.
       */
      static bool start();

      /** Destructor */
      virtual ~KUniqueApplication();

      /**
       * Retrieve the DCOP client object.
       **/
      virtual DCOPClient *dcopClient();

      /**
       * Dispatch any incoming DCOP message for a new instance.
       *
       * If it is not a request for a new instance, return @p false.
       */
      bool process(const QCString &fun, const QByteArray &data,
    	       QCString &replyType, QByteArray &replyData);

      /**
       * Create a new "instance" of the application.
       *
       * Usually this will involve making some calls into the GUI portion of your
       * application asking for a new window to be created, possibly with
       * some data already loaded based on the arguments received.
       *
       * Command line arguments have been passed to KCmdLineArgs before this
       * function is called and can be checked in the usual way.
       *
       * @return An exit value. The calling process will exit with this value.
       */
      virtual int newInstance();

    private:
      /**
       * @deprecated Do not use!
       */
      virtual int newInstance(QValueList<QCString>);

      /**
       * Delay the processing of a DCOP request.
       */
      void delayRequest(const QCString &fun, const QByteArray &data);

    private slots:
      /**
       * Delayed processing of DCOP requests.
       */
      void processDelayed();

      void newInstanceNoFork();

    private:
      static DCOPClient *s_DCOPClient;
      static bool s_nofork;

      KUniqueApplicationPrivate *d;
    };

    #endif

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