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How to solve Object::connect: No such signal

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  • mranger90M Offline
    mranger90M Offline
    mranger90
    wrote on last edited by
    #3
    This post is deleted!
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    • sierdzioS sierdzio

      You are mixing old and new connect syntax.

      Either use this:

      // Old syntax
      connect(this, SIGNAL(MainWindow::newImage(const QImage)), this, SLOT(MainWindow::setImage(const QImage)));
      

      Or this:

      // New syntax:
      connect(this, &MainWindow::newImage, this, &MainWindow::setImage);
      

      I recommend using new syntax whenever possible.

      J Offline
      J Offline
      jaouad100
      wrote on last edited by
      #4

      @sierdzio I was using the new version but I get the error of matching error: no matching function for call to ‘qdude::MainWindow::connect(qdude::MainWindow*, void (qdude::MainWindow::*)(const QImage&), qdude::MainWindow*, void (qdude::MainWindow::*)(const QImage&))’

      JonBJ 1 Reply Last reply
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      • sierdzioS Offline
        sierdzioS Offline
        sierdzio
        Moderators
        wrote on last edited by
        #5

        @jaouad100 said in How to solve Object::connect: No such signal:

        void setImage(const QImage &);

        Make this method as slot:

        protected slots:
          void setImage(const QImage &);
        

        (Z(:^

        J 1 Reply Last reply
        0
        • sierdzioS sierdzio

          @jaouad100 said in How to solve Object::connect: No such signal:

          void setImage(const QImage &);

          Make this method as slot:

          protected slots:
            void setImage(const QImage &);
          
          J Offline
          J Offline
          jaouad100
          wrote on last edited by
          #6

          @sierdzio The same issue :/

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          • J jaouad100

            @sierdzio I was using the new version but I get the error of matching error: no matching function for call to ‘qdude::MainWindow::connect(qdude::MainWindow*, void (qdude::MainWindow::*)(const QImage&), qdude::MainWindow*, void (qdude::MainWindow::*)(const QImage&))’

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by
            #7

            @jaouad100 said in How to solve Object::connect: No such signal:

            @sierdzio I was using the new version

            If you say you are using the "new version" syntax, we would not expect to see SIGNAL() or SLOT().

            Would you care to either confirm your code is still exactly as shown in your first post, or update it correctly?

            J 1 Reply Last reply
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            • JonBJ JonB

              @jaouad100 said in How to solve Object::connect: No such signal:

              @sierdzio I was using the new version

              If you say you are using the "new version" syntax, we would not expect to see SIGNAL() or SLOT().

              Would you care to either confirm your code is still exactly as shown in your first post, or update it correctly?

              J Offline
              J Offline
              jaouad100
              wrote on last edited by
              #8

              @JonB I confirm that the code posted is the version I'm working on at the moment

              JonBJ 1 Reply Last reply
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              • J jaouad100

                @JonB I confirm that the code posted is the version I'm working on at the moment

                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by JonB
                #9

                @jaouad100
                Then I think (I am not a C++-er) you'll find that as @sierdzio wrote for the old syntax you need to remove the two & characters prior to MainWindow:: in both SIGNAL() & SLOT() (because they effectively put their own & in for you) ....

                J 1 Reply Last reply
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                • JonBJ JonB

                  @jaouad100
                  Then I think (I am not a C++-er) you'll find that as @sierdzio wrote for the old syntax you need to remove the two & characters prior to MainWindow:: in both SIGNAL() & SLOT() (because they effectively put their own & in for you) ....

                  J Offline
                  J Offline
                  jaouad100
                  wrote on last edited by
                  #10

                  @JonB Yes I noticed that but it is not the issue

                  JonBJ 1 Reply Last reply
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                  • J jaouad100

                    @JonB Yes I noticed that but it is not the issue

                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by JonB
                    #11

                    @jaouad100
                    If it is not the issue, then why does your error message read:
                    qdude::MainWindow::&MainWindow::newImage(const QImage&*)
                    with that middling & in it? I believe it is....

                    If I wanted to use the old syntax, I would be writing:

                    QObject::connect(this, SIGNAL(newImage(const QImage &)), this, SLOT(setImage(const QImage &)));
                    

                    exactly as per e.g. http://doc.qt.io/qt-5/qobject.html#connect

                    J 1 Reply Last reply
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                    • JonBJ JonB

                      @jaouad100
                      If it is not the issue, then why does your error message read:
                      qdude::MainWindow::&MainWindow::newImage(const QImage&*)
                      with that middling & in it? I believe it is....

                      If I wanted to use the old syntax, I would be writing:

                      QObject::connect(this, SIGNAL(newImage(const QImage &)), this, SLOT(setImage(const QImage &)));
                      

                      exactly as per e.g. http://doc.qt.io/qt-5/qobject.html#connect

                      J Offline
                      J Offline
                      jaouad100
                      wrote on last edited by
                      #12

                      @JonB Yes you're right. It was not only the reference because I tried without the reference but it didn't work but also the qualification on the names MainWindow:: I took it off and now it works, thanks!

                      1 Reply Last reply
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