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Mainwindow closes when I close PCL window.

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  • J jsulm
    3 May 2021, 08:13

    @surajj4837 Also, does pcl::visualization::CloudViewer allocate the actual dialog on the heap?

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    surajj4837
    wrote on 3 May 2021, 08:25 last edited by
    #17

    @jsulm The CloudViewer constructor definition says it creates the object on heap.

    J 1 Reply Last reply 3 May 2021, 08:30
    0
    • J JonB
      3 May 2021, 08:14

      @surajj4837
      For one thing, because of your

      pcl::visualization::CloudViewer viewer("Cloud Viewer");
      

      local variable this will be automatically destructed on reaching the end of function's } scope. You shouldn't call the destructor explicitly, even if that was OK I imagine it would cause double-destruction on exiting the method....

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      surajj4837
      wrote on 3 May 2021, 08:27 last edited by
      #18

      @JonB https://www.geeksforgeeks.org/possible-call-constructor-destructor-explicitly/

      C J 2 Replies Last reply 3 May 2021, 08:28
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      • S surajj4837
        3 May 2021, 08:27

        @JonB https://www.geeksforgeeks.org/possible-call-constructor-destructor-explicitly/

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        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on 3 May 2021, 08:28 last edited by Christian Ehrlicher 5 Mar 2021, 08:29
        #19

        @surajj4837 You must not call a dtor for an object when you created it on the stack as you did - no matter if you call it in an unusual way like you did or with the correct c++ way by calling delete. C++ basics.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
        Visit the Qt Academy at https://academy.qt.io/catalog

        S 1 Reply Last reply 3 May 2021, 08:31
        1
        • S surajj4837
          3 May 2021, 08:27

          @JonB https://www.geeksforgeeks.org/possible-call-constructor-destructor-explicitly/

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          JonB
          wrote on 3 May 2021, 08:28 last edited by JonB 5 Mar 2021, 08:29
          #20

          @surajj4837

          @JonB https://www.geeksforgeeks.org/possible-call-constructor-destructor-explicitly/

          Explicit call to destructor is only necessary when object is placed at particular location in memory by using placement new.

          Do you have any evidence this is the case for you?

          S 1 Reply Last reply 3 May 2021, 08:31
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          • S surajj4837
            3 May 2021, 08:25

            @jsulm The CloudViewer constructor definition says it creates the object on heap.

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            jsulm
            Lifetime Qt Champion
            wrote on 3 May 2021, 08:30 last edited by
            #21

            @surajj4837 said in Mainwindow closes when I close PCL window.:

            The CloudViewer constructor definition says it creates the object on heap

            Please show its code. viewer itself is allocated on the stack as you can clearly see from your code...

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

            S 1 Reply Last reply 3 May 2021, 08:32
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            • C Christian Ehrlicher
              3 May 2021, 08:28

              @surajj4837 You must not call a dtor for an object when you created it on the stack as you did - no matter if you call it in an unusual way like you did or with the correct c++ way by calling delete. C++ basics.

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              surajj4837
              wrote on 3 May 2021, 08:31 last edited by
              #22

              @Christian-Ehrlicher Okay

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              • J JonB
                3 May 2021, 08:28

                @surajj4837

                @JonB https://www.geeksforgeeks.org/possible-call-constructor-destructor-explicitly/

                Explicit call to destructor is only necessary when object is placed at particular location in memory by using placement new.

                Do you have any evidence this is the case for you?

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                surajj4837
                wrote on 3 May 2021, 08:31 last edited by
                #23

                @JonB No.

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                • J jsulm
                  3 May 2021, 08:30

                  @surajj4837 said in Mainwindow closes when I close PCL window.:

                  The CloudViewer constructor definition says it creates the object on heap

                  Please show its code. viewer itself is allocated on the stack as you can clearly see from your code...

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                  surajj4837
                  wrote on 3 May 2021, 08:32 last edited by
                  #24

                  @jsulm Official source code. Line #266.

                  J C 4 Replies Last reply 3 May 2021, 08:32
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                  • S surajj4837
                    3 May 2021, 08:32

                    @jsulm Official source code. Line #266.

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                    jsulm
                    Lifetime Qt Champion
                    wrote on 3 May 2021, 08:32 last edited by
                    #25

                    @surajj4837 said in Mainwindow closes when I close PCL window.:

                    Line #266.

                    What is in that line?

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

                    1 Reply Last reply
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                    • S surajj4837
                      3 May 2021, 08:32

                      @jsulm Official source code. Line #266.

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                      Christian Ehrlicher
                      Lifetime Qt Champion
                      wrote on 3 May 2021, 08:33 last edited by
                      #26

                      @surajj4837 said in Mainwindow closes when I close PCL window.:

                      @jsulm Official source code. Line #266.

                      There the object itself creates a new object on the heap. Don't know what this should have to do with your object which you create on the stack though.

                      Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                      Visit the Qt Academy at https://academy.qt.io/catalog

                      1 Reply Last reply
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                      • S surajj4837
                        3 May 2021, 08:32

                        @jsulm Official source code. Line #266.

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                        jsulm
                        Lifetime Qt Champion
                        wrote on 3 May 2021, 08:35 last edited by jsulm 5 Mar 2021, 08:35
                        #27

                        @surajj4837 This does not change anything! viewer is allocated on the stack. Its constructor allocates something on the heap but that is deleted in the destructor. But you do not have to call destructor for objects allocated on the stack as it is called when the object is destroyed (if it leaves its scope). I suggest you learn C++ basics (memory management).

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

                        S 1 Reply Last reply 3 May 2021, 08:38
                        1
                        • S surajj4837
                          3 May 2021, 08:32

                          @jsulm Official source code. Line #266.

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                          jsulm
                          Lifetime Qt Champion
                          wrote on 3 May 2021, 08:37 last edited by
                          #28

                          @surajj4837 Actually there seems to be a bug:

                          00270 pcl::visualization::CloudViewer::~CloudViewer ()
                          00271 {
                          00272   impl_->quit_ = true;
                          00273   impl_->viewer_thread_.join();
                          00274 }
                          00275 
                          

                          Destructor does not delete impl!
                          It should be

                          pcl::visualization::CloudViewer::~CloudViewer ()
                          {
                             impl_->quit_ = true;
                             impl_->viewer_thread_.join();
                             delete impl;
                          }
                          

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

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                          • J jsulm
                            3 May 2021, 08:35

                            @surajj4837 This does not change anything! viewer is allocated on the stack. Its constructor allocates something on the heap but that is deleted in the destructor. But you do not have to call destructor for objects allocated on the stack as it is called when the object is destroyed (if it leaves its scope). I suggest you learn C++ basics (memory management).

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                            surajj4837
                            wrote on 3 May 2021, 08:38 last edited by
                            #29

                            @jsulm Sure, I will do that.

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