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Problem in Connecting ctkDoubleSpinBox

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  • jsulmJ jsulm

    @Meera-Hadid Try to do the connect using new connect syntax https://doc.qt.io/qt-5/signalsandslots.html

    M Offline
    M Offline
    Meera Hadid
    wrote on last edited by
    #10

    @jsulm

    • do you mean this syntax?
     Counter a, b;
        QObject::connect(&a, &Counter::valueChanged,
                         &b, &Counter::setValue);
    
    • I am getting a syntax error when I use this: this->SliceController->&spinBox
    JonBJ 1 Reply Last reply
    0
    • M Meera Hadid

      @jsulm

      • do you mean this syntax?
       Counter a, b;
          QObject::connect(&a, &Counter::valueChanged,
                           &b, &Counter::setValue);
      
      • I am getting a syntax error when I use this: this->SliceController->&spinBox
      JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by JonB
      #11

      @Meera-Hadid said in Problem in Connecting ctkDoubleSpinBox:

      I am getting a syntax error when I use this: this->SliceController->&spinBox

      This is not legal C++. It should be:

      &this->SliceController->spinBox
      

      Whether you want the & depends on whether spinbox is already a pointer or not (I think yours is a pointer, in which case you would not want it?)

      M 1 Reply Last reply
      1
      • Christian EhrlicherC Online
        Christian EhrlicherC Online
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on last edited by
        #12

        @JonB said in Problem in Connecting ctkDoubleSpinBox:

        &this->SliceController->spinBox

        But according to the error message

        cannot convert argument 1 from 'ctkDoubleSpinBox *' to 'const QObject *

        It's already a pointer so the & is wrong.
        I still think the header for this class is not included where the connect is done so the compiler doesn't know that ctkDoubleSpinBox is derived from QObject.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
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        M 1 Reply Last reply
        2
        • Christian EhrlicherC Christian Ehrlicher

          @JonB said in Problem in Connecting ctkDoubleSpinBox:

          &this->SliceController->spinBox

          But according to the error message

          cannot convert argument 1 from 'ctkDoubleSpinBox *' to 'const QObject *

          It's already a pointer so the & is wrong.
          I still think the header for this class is not included where the connect is done so the compiler doesn't know that ctkDoubleSpinBox is derived from QObject.

          M Offline
          M Offline
          Meera Hadid
          wrote on last edited by
          #13

          @Christian-Ehrlicher

          • I did include #include <ctkDoubleSpinBox.h>
          jsulmJ 1 Reply Last reply
          0
          • M Meera Hadid

            @Christian-Ehrlicher

            • I did include #include <ctkDoubleSpinBox.h>
            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #14

            @Meera-Hadid Fix your connect as suggested by @JonB and try again

            https://forum.qt.io/topic/113070/qt-code-of-conduct

            1 Reply Last reply
            0
            • JonBJ JonB

              @Meera-Hadid said in Problem in Connecting ctkDoubleSpinBox:

              I am getting a syntax error when I use this: this->SliceController->&spinBox

              This is not legal C++. It should be:

              &this->SliceController->spinBox
              

              Whether you want the & depends on whether spinbox is already a pointer or not (I think yours is a pointer, in which case you would not want it?)

              M Offline
              M Offline
              Meera Hadid
              wrote on last edited by
              #15

              @JonB

              • Yes when I tried without using & it was raising an error that cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

              @jsulm

              • The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'
              JonBJ jsulmJ 3 Replies Last reply
              0
              • M Meera Hadid

                @JonB

                • Yes when I tried without using & it was raising an error that cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                @jsulm

                • The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'
                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by
                #16

                @Meera-Hadid said in Problem in Connecting ctkDoubleSpinBox:

                @JonB

                Yes when I tried without using & it was raising an error that cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                @jsulm

                The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                Inserting a & randomly will not help. The message already tells that pointer-ness is not the issue.

                1 Reply Last reply
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                • M Meera Hadid

                  @JonB

                  • Yes when I tried without using & it was raising an error that cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                  @jsulm

                  • The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'
                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #17

                  @Meera-Hadid said in Problem in Connecting ctkDoubleSpinBox:

                  The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                  Do you mean you get same error message if you use new connect syntax?

                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  1
                  • M Meera Hadid

                    @JonB

                    • Yes when I tried without using & it was raising an error that cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'

                    @jsulm

                    • The issue is not getting pointer the issue is it cannot convert from 'ctkDoubleSpinBox *' to 'const QObject *'
                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by JonB
                    #18

                    @Meera-Hadid
                    Please do the following:

                    • First, delete all the files from the build output directory. Do a fresh qmake followed by a build. Does the error still occur?
                    • From the line number in the error message, are you quite sure it is on the connect() statement you have shown, and not some other?
                    • I believe I already advised this before in answer to the same problem from you in another thread: on the line above the connect() put in
                    const QObject *temp = this->SliceController->spinBox;
                    

                    Does that error (show message)?

                    M 1 Reply Last reply
                    0
                    • JonBJ JonB

                      @Meera-Hadid
                      Please do the following:

                      • First, delete all the files from the build output directory. Do a fresh qmake followed by a build. Does the error still occur?
                      • From the line number in the error message, are you quite sure it is on the connect() statement you have shown, and not some other?
                      • I believe I already advised this before in answer to the same problem from you in another thread: on the line above the connect() put in
                      const QObject *temp = this->SliceController->spinBox;
                      

                      Does that error (show message)?

                      M Offline
                      M Offline
                      Meera Hadid
                      wrote on last edited by
                      #19

                      @JonB

                      • const QObject *temp = this->SliceController->spinBox;
                        this works
                      • But the signal SIGNAL(valueChanged(double)) doesn't get activated (QLabel value doesn't change). Is it because temp is returing nullptr?
                      JonBJ 1 Reply Last reply
                      0
                      • M Meera Hadid

                        @JonB

                        • const QObject *temp = this->SliceController->spinBox;
                          this works
                        • But the signal SIGNAL(valueChanged(double)) doesn't get activated (QLabel value doesn't change). Is it because temp is returing nullptr?
                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by
                        #20

                        @Meera-Hadid

                        Is it because temp is returing nullptr?

                        Pardon? Are you saying this->SliceController->spinBox == nullptr at the time you execute the connect() statement?

                        Separately, put a qDebug() statement as the first thing in your void qMRMLSliceWidget::updateLabel().

                        M 1 Reply Last reply
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                        • JonBJ JonB

                          @Meera-Hadid

                          Is it because temp is returing nullptr?

                          Pardon? Are you saying this->SliceController->spinBox == nullptr at the time you execute the connect() statement?

                          Separately, put a qDebug() statement as the first thing in your void qMRMLSliceWidget::updateLabel().

                          M Offline
                          M Offline
                          Meera Hadid
                          wrote on last edited by
                          #21

                          @JonB said in Problem in Connecting ctkDoubleSpinBox:

                          Separately, put a qDebug() statement as the first thing in your void qMRMLSliceWidget::updateLabel().

                          Yes I did but that statement is not getting printed/executed

                          JonBJ 1 Reply Last reply
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                          • M Meera Hadid

                            @JonB said in Problem in Connecting ctkDoubleSpinBox:

                            Separately, put a qDebug() statement as the first thing in your void qMRMLSliceWidget::updateLabel().

                            Yes I did but that statement is not getting printed/executed

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by
                            #22

                            @Meera-Hadid
                            I have asked you other questions. If you don't want to respond to them that is up to you.

                            M 1 Reply Last reply
                            0
                            • JonBJ JonB

                              @Meera-Hadid
                              I have asked you other questions. If you don't want to respond to them that is up to you.

                              M Offline
                              M Offline
                              Meera Hadid
                              wrote on last edited by
                              #23

                              @JonB

                              • First, delete all the files from the build output directory. Do a fresh qmake followed by a build. Does the error still occur?
                                Since there are a lot of files it takes a lot of time to build hence I did not clear the build.
                              • It's my bad that I assumed this->SliceController->spinBox was returning a nullptr. The problem was with slot I changed it.
                              • const QObject *temp = this->SliceController->spinBox; worked for me

                              Thanks everyone for contributing.

                              1 Reply Last reply
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