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QObject::connect returns false

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  • SPlattenS SPlatten

    @JonB , so the source now reads:

    Q_ASSERT(pobjEmulator);
    Q_ASSERT(pobjService);
    bool blnRC(QObject::connect(pobjEmulator, SIGNAL(epoch(long))
                               ,pobjService, SLOT(updateTime(long))));
    

    Built and run, no assertions, blnRC is false.

    JonBJ Offline
    JonBJ Offline
    JonB
    wrote on last edited by
    #15

    @SPlatten said in QObject::connect returns false:

    Built and run, no assertions, blnRC is false.

    Just checking: how do you know that? I wouldn't trist that if you are only viewing in debugger, as I believe you sometimes do; are you actually outputting the variable's value?

    SPlattenS 1 Reply Last reply
    0
    • KroMignonK KroMignon

      @J-Hilk said in QObject::connect returns false:

      or more in general, the long typdef may not be correctly registered with the meta system.

      But this would not affect to connect() call, only slot may not be called if sender and receiver not in same thread.

      For my comprehension of QObject signals/slots, connect() will only fail if no machting signal or slot signature are found in meta-data. Which are generated by moc.

      SPlattenS Offline
      SPlattenS Offline
      SPlatten
      wrote on last edited by
      #16

      @KroMignon I will look at the generated moc files, but as you can see from my posts the prototypes are identical.

      Kind Regards,
      Sy

      JonBJ KroMignonK 2 Replies Last reply
      0
      • JonBJ JonB

        @SPlatten said in QObject::connect returns false:

        Built and run, no assertions, blnRC is false.

        Just checking: how do you know that? I wouldn't trist that if you are only viewing in debugger, as I believe you sometimes do; are you actually outputting the variable's value?

        SPlattenS Offline
        SPlattenS Offline
        SPlatten
        wrote on last edited by
        #17

        @JonB , I have a break point in the debugger after the connect and can see it contains false.

        Kind Regards,
        Sy

        JonBJ 1 Reply Last reply
        0
        • SPlattenS SPlatten

          @KroMignon I will look at the generated moc files, but as you can see from my posts the prototypes are identical.

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by
          #18

          @SPlatten
          Per @KroMignon, just start by emptying out your build output directory and doing a complete rebuild, just in case. Always start there when Qt gives you something "inexplicable" :)

          1 Reply Last reply
          0
          • JonBJ JonB

            @SPlatten
            Sorry, what's wrong with what?
            My previous post was just expressing surprise to @J-Hilk that long type might not be "registered with the meta system", but he knows more than I....

            KroMignonK Offline
            KroMignonK Offline
            KroMignon
            wrote on last edited by
            #19

            @JonB said in QObject::connect returns false:

            My previous post was just expressing surprise to @J-Hilk that long type might not be "registered with the meta system", but he knows more than I..

            For inter-thread communication, or in case of Qt::QueuedConnection, parameters needs to be copied. So QMeta needs to know how to create a copy of them. This is way all types needs to be registered. Some are already registered my Qt, some not ;)

            It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

            1 Reply Last reply
            0
            • SPlattenS SPlatten

              @JonB , I have a break point in the debugger after the connect and can see it contains false.

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by
              #20

              @SPlatten said in QObject::connect returns false:

              @JonB , I have a break point in the debugger after the connect and can see it contains false.

              Noooo.
              Like I said, print it out........

              SPlattenS 1 Reply Last reply
              0
              • JonBJ JonB

                @SPlatten said in QObject::connect returns false:

                @JonB , I have a break point in the debugger after the connect and can see it contains false.

                Noooo.
                Like I said, print it out........

                SPlattenS Offline
                SPlattenS Offline
                SPlatten
                wrote on last edited by
                #21

                @JonB, just did that adding:

                qDebug() << "connect: " << blnRC;
                

                Shown in console as:

                connect: false
                

                Kind Regards,
                Sy

                JonBJ 2 Replies Last reply
                0
                • SPlattenS SPlatten

                  @JonB, just did that adding:

                  qDebug() << "connect: " << blnRC;
                  

                  Shown in console as:

                  connect: false
                  
                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by
                  #22

                  @SPlatten
                  OK, damn!
                  Just I warn you now: do not rely on what you see in the debugger for values of variables...!

                  1 Reply Last reply
                  0
                  • SPlattenS SPlatten

                    @KroMignon I will look at the generated moc files, but as you can see from my posts the prototypes are identical.

                    KroMignonK Offline
                    KroMignonK Offline
                    KroMignon
                    wrote on last edited by
                    #23

                    @SPlatten said in QObject::connect returns false:

                    I will look at the generated moc files, but as you can see from my posts the prototypes are identical.

                    Are you sure header files are in HEADERS in your PRO file?
                    Did you (re)run qmake?
                    You could also try to remove the build directory to force moc re-run.

                    It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                    1 Reply Last reply
                    2
                    • SPlattenS SPlatten

                      @JonB, just did that adding:

                      qDebug() << "connect: " << blnRC;
                      

                      Shown in console as:

                      connect: false
                      
                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by
                      #24

                      @SPlatten
                      Like I said, have you done a delete and fresh rebuild?
                      Does clsTimeEmu have Q_OBJECT in it?

                      1 Reply Last reply
                      0
                      • SPlattenS Offline
                        SPlattenS Offline
                        SPlatten
                        wrote on last edited by
                        #25

                        @J-Hilk , @JonB , @KroMignon , I've looked at both moc files, moc_clsTimeEmu.cpp has the signal:

                        // SIGNAL_0
                        void clsTimeEmu::epoch(int _t1)
                        {
                            void *_a[] = { 0, const_cast<void*>reinterpret_cast<const void*>(&_t)) };
                            QMetaObject::activate(this, &staticMetaObject, 0, _a);
                        }
                        

                        moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                        Kind Regards,
                        Sy

                        J.HilkJ KroMignonK JonBJ 3 Replies Last reply
                        0
                        • SPlattenS SPlatten

                          @J-Hilk , @JonB , @KroMignon , I've looked at both moc files, moc_clsTimeEmu.cpp has the signal:

                          // SIGNAL_0
                          void clsTimeEmu::epoch(int _t1)
                          {
                              void *_a[] = { 0, const_cast<void*>reinterpret_cast<const void*>(&_t)) };
                              QMetaObject::activate(this, &staticMetaObject, 0, _a);
                          }
                          

                          moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                          J.HilkJ Offline
                          J.HilkJ Offline
                          J.Hilk
                          Moderators
                          wrote on last edited by J.Hilk
                          #26

                          @SPlatten well, can you post more of the clsSchdSrv header ?


                          Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                          Q: What's that?
                          A: It's blue light.
                          Q: What does it do?
                          A: It turns blue.

                          SPlattenS 1 Reply Last reply
                          0
                          • SPlattenS SPlatten

                            @J-Hilk , @JonB , @KroMignon , I've looked at both moc files, moc_clsTimeEmu.cpp has the signal:

                            // SIGNAL_0
                            void clsTimeEmu::epoch(int _t1)
                            {
                                void *_a[] = { 0, const_cast<void*>reinterpret_cast<const void*>(&_t)) };
                                QMetaObject::activate(this, &staticMetaObject, 0, _a);
                            }
                            

                            moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                            KroMignonK Offline
                            KroMignonK Offline
                            KroMignon
                            wrote on last edited by
                            #27

                            @SPlatten said in QObject::connect returns false:

                            moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                            Some time Qt-Creator do not detect changes is HEADERS files, so moc will not be re-run.
                            This is why I suggest you to try to re-run yourself qmake and, if this not help, remove the build directory (as also suggested by @JonB ) to force full rebuild (with moc).

                            But first, make sure all headers are present in HEADERS of your PRO file.

                            It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                            SPlattenS 1 Reply Last reply
                            0
                            • J.HilkJ J.Hilk

                              @SPlatten well, can you post more of the clsSchdSrv header ?

                              SPlattenS Offline
                              SPlattenS Offline
                              SPlatten
                              wrote on last edited by SPlatten
                              #28

                              @J-Hilk , clsSchdSrv.h, still a early work in progress:

                              class clsSchdSrv : public QTimer {
                                  Q_OBJECT
                              
                              public:
                                  explicit clsSchdSrv(QObject* pParent = 0);
                                  void kick();
                              
                              public slots:
                                  virtual void expired() = 0;
                              }
                              

                              Sorry, should have added:

                              class clsTimeSync : public clsSchdSrv {
                              public:
                                  explicit clsTimeSync();
                              
                              public slots:
                                  virtual void expired();
                                  void updateTime(int intTimeNow);
                              }
                              

                              Kind Regards,
                              Sy

                              jsulmJ J.HilkJ JonBJ KroMignonK 4 Replies Last reply
                              0
                              • SPlattenS SPlatten

                                @J-Hilk , @JonB , @KroMignon , I've looked at both moc files, moc_clsTimeEmu.cpp has the signal:

                                // SIGNAL_0
                                void clsTimeEmu::epoch(int _t1)
                                {
                                    void *_a[] = { 0, const_cast<void*>reinterpret_cast<const void*>(&_t)) };
                                    QMetaObject::activate(this, &staticMetaObject, 0, _a);
                                }
                                

                                moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                                JonBJ Offline
                                JonBJ Offline
                                JonB
                                wrote on last edited by
                                #29

                                @SPlatten
                                We have all said several times to try a complete delete and re-build.....

                                1 Reply Last reply
                                0
                                • SPlattenS SPlatten

                                  @J-Hilk , clsSchdSrv.h, still a early work in progress:

                                  class clsSchdSrv : public QTimer {
                                      Q_OBJECT
                                  
                                  public:
                                      explicit clsSchdSrv(QObject* pParent = 0);
                                      void kick();
                                  
                                  public slots:
                                      virtual void expired() = 0;
                                  }
                                  

                                  Sorry, should have added:

                                  class clsTimeSync : public clsSchdSrv {
                                  public:
                                      explicit clsTimeSync();
                                  
                                  public slots:
                                      virtual void expired();
                                      void updateTime(int intTimeNow);
                                  }
                                  
                                  jsulmJ Offline
                                  jsulmJ Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on last edited by
                                  #30

                                  @SPlatten You should see a warning at runtime when connect is executed: what does it say?

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

                                  1 Reply Last reply
                                  0
                                  • KroMignonK KroMignon

                                    @SPlatten said in QObject::connect returns false:

                                    moc_clsSchdSrv.cpp does not have anything that looks like the slot, no mention of updateTime at all, why ?

                                    Some time Qt-Creator do not detect changes is HEADERS files, so moc will not be re-run.
                                    This is why I suggest you to try to re-run yourself qmake and, if this not help, remove the build directory (as also suggested by @JonB ) to force full rebuild (with moc).

                                    But first, make sure all headers are present in HEADERS of your PRO file.

                                    SPlattenS Offline
                                    SPlattenS Offline
                                    SPlatten
                                    wrote on last edited by
                                    #31

                                    @KroMignon, I deleted the content of the build folder , checking for any hidden files, then ran clean, remake and build, same results.

                                    Kind Regards,
                                    Sy

                                    1 Reply Last reply
                                    0
                                    • SPlattenS SPlatten

                                      @J-Hilk , clsSchdSrv.h, still a early work in progress:

                                      class clsSchdSrv : public QTimer {
                                          Q_OBJECT
                                      
                                      public:
                                          explicit clsSchdSrv(QObject* pParent = 0);
                                          void kick();
                                      
                                      public slots:
                                          virtual void expired() = 0;
                                      }
                                      

                                      Sorry, should have added:

                                      class clsTimeSync : public clsSchdSrv {
                                      public:
                                          explicit clsTimeSync();
                                      
                                      public slots:
                                          virtual void expired();
                                          void updateTime(int intTimeNow);
                                      }
                                      
                                      J.HilkJ Offline
                                      J.HilkJ Offline
                                      J.Hilk
                                      Moderators
                                      wrote on last edited by
                                      #32

                                      @SPlatten if thats the header, than I as well fail to see the slot void updateTime(long); declaration ;)


                                      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                      Q: What's that?
                                      A: It's blue light.
                                      Q: What does it do?
                                      A: It turns blue.

                                      1 Reply Last reply
                                      0
                                      • SPlattenS SPlatten

                                        @J-Hilk , clsSchdSrv.h, still a early work in progress:

                                        class clsSchdSrv : public QTimer {
                                            Q_OBJECT
                                        
                                        public:
                                            explicit clsSchdSrv(QObject* pParent = 0);
                                            void kick();
                                        
                                        public slots:
                                            virtual void expired() = 0;
                                        }
                                        

                                        Sorry, should have added:

                                        class clsTimeSync : public clsSchdSrv {
                                        public:
                                            explicit clsTimeSync();
                                        
                                        public slots:
                                            virtual void expired();
                                            void updateTime(int intTimeNow);
                                        }
                                        
                                        JonBJ Offline
                                        JonBJ Offline
                                        JonB
                                        wrote on last edited by JonB
                                        #33

                                        @SPlatten said in QObject::connect returns false:

                                        public slots:
                                        virtual void expired() = 0;

                                        But you use SLOT(updateTime())?

                                        Why are you showing us clsSchdSrv? Earlier you showed clsTimeSync?

                                        SPlattenS 1 Reply Last reply
                                        0
                                        • SPlattenS SPlatten

                                          @J-Hilk , clsSchdSrv.h, still a early work in progress:

                                          class clsSchdSrv : public QTimer {
                                              Q_OBJECT
                                          
                                          public:
                                              explicit clsSchdSrv(QObject* pParent = 0);
                                              void kick();
                                          
                                          public slots:
                                              virtual void expired() = 0;
                                          }
                                          

                                          Sorry, should have added:

                                          class clsTimeSync : public clsSchdSrv {
                                          public:
                                              explicit clsTimeSync();
                                          
                                          public slots:
                                              virtual void expired();
                                              void updateTime(int intTimeNow);
                                          }
                                          
                                          KroMignonK Offline
                                          KroMignonK Offline
                                          KroMignon
                                          wrote on last edited by
                                          #34

                                          @SPlatten said in QObject::connect returns false:

                                          clsSchdSrv.h, still a early work in progress:

                                          I am not sure, you can declare a slot as virtual.
                                          I would change this to:

                                          class clsSchdSrv : public QTimer {
                                              Q_OBJECT
                                          
                                          public:
                                              explicit clsSchdSrv(QObject* pParent = 0);
                                              void kick();
                                          
                                          public:
                                               virtual void  onExpired() = 0;
                                          public slots:
                                              void expired() {  onExpired(); } 
                                          }
                                          

                                          It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                                          1 Reply Last reply
                                          0

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