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Help with QTimer scope

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  • C Christianvs

    @sierdzio @aha_1980 @jsulm

    Thanks for the answers! I've tried following (i'm sorry about the messy code, in my attempt to get this working lines have been added, changed and commented out):

    0_1520248658951_72b4fec2-16da-4dc9-8bb0-e1d02793c340-image.png

    I am not sure if i get the new connect method right. In the case it should be the right way i connect it, i still seem to have the same problem as before.

    @jsulm
    I actually started out with initializing the Qtimers in the header file, but in my search for my mistake i tried allocating on the heap

    aha_1980A Offline
    aha_1980A Offline
    aha_1980
    Lifetime Qt Champion
    wrote on last edited by
    #8

    @Christianvs Are you sure your debug output works? Can you set a breakpoint in the slot?

    Beside the "mess" your code looks Ok.

    If it still not works, you have to look if you somewhere block signals or if the event loop is not running etc.

    Qt has to stay free or it will die.

    1 Reply Last reply
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    • jsulmJ jsulm

      @Christianvs What is ROS_INFO_STREAM?
      Can you try qDebug() instead to verify the slot is called?

      C Offline
      C Offline
      Christianvs
      wrote on last edited by Christianvs
      #9

      @jsulm

      The whole project is connected through ROS as it controls an AC motor. To be honest i'm not sure if qDebug works in my current setup.

      None the less i got the timer to say it's active by running isActive() after i start the timer (what a stupid mistake!)

      But that actually solves part of my problem as i now know the timer is actually active!

      But it still does not execute the timerTest() function!

      jsulmJ 1 Reply Last reply
      0
      • C Christianvs

        @jsulm

        The whole project is connected through ROS as it controls an AC motor. To be honest i'm not sure if qDebug works in my current setup.

        None the less i got the timer to say it's active by running isActive() after i start the timer (what a stupid mistake!)

        But that actually solves part of my problem as i now know the timer is actually active!

        But it still does not execute the timerTest() function!

        jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #10

        @Christianvs said in Help with QTimer scope:

        qDebug works in my current setup

        std::cout should work.
        And you can place a breakpoint inside the slot and start through debugger.

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

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        • C Offline
          C Offline
          Christianvs
          wrote on last edited by
          #11

          Could the problem be that my weightChanger object somehow needs to be initialized in another way? By using new ?

          0_1520249436236_6d85866a-a01e-4a81-b0ed-645520a5e3fa-image.png

          Above is where i actually initialize the object and it is within this object the QTimer is stored

          sierdzioS 1 Reply Last reply
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          • C Christianvs

            Could the problem be that my weightChanger object somehow needs to be initialized in another way? By using new ?

            0_1520249436236_6d85866a-a01e-4a81-b0ed-645520a5e3fa-image.png

            Above is where i actually initialize the object and it is within this object the QTimer is stored

            sierdzioS Offline
            sierdzioS Offline
            sierdzio
            Moderators
            wrote on last edited by
            #12

            @Christianvs said in Help with QTimer scope:

            Could the problem be that my weightChanger object somehow needs to be initialized in another way? By using new ?

            Yes! When this function ends, it will be destroyed (object goes out of scope).

            (Z(:^

            jsulmJ 1 Reply Last reply
            2
            • sierdzioS sierdzio

              @Christianvs said in Help with QTimer scope:

              Could the problem be that my weightChanger object somehow needs to be initialized in another way? By using new ?

              Yes! When this function ends, it will be destroyed (object goes out of scope).

              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #13

              @sierdzio @Christianvs You can see this type of error very often here :-)

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

              1 Reply Last reply
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              • C Offline
                C Offline
                Christianvs
                wrote on last edited by
                #14

                Yay! Now that i create it on the heap using new the timers work without any problems!

                Thanks for the help all of you! :)

                1 Reply Last reply
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                • sierdzioS Offline
                  sierdzioS Offline
                  sierdzio
                  Moderators
                  wrote on last edited by
                  #15

                  Just make sure it is cleaned up properly afterwards (either assign this as parent or call delete on it when you don't need it anymore).

                  (Z(:^

                  C 1 Reply Last reply
                  1
                  • Pablo J. RoginaP Offline
                    Pablo J. RoginaP Offline
                    Pablo J. Rogina
                    wrote on last edited by
                    #16

                    @Christianvs if your issue is solved, please don't forget to mark your post as such. Thanks.

                    Upvote the answer(s) that helped you solve the issue
                    Use "Topic Tools" button to mark your post as Solved
                    Add screenshots via postimage.org
                    Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

                    1 Reply Last reply
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                    • sierdzioS sierdzio

                      Just make sure it is cleaned up properly afterwards (either assign this as parent or call delete on it when you don't need it anymore).

                      C Offline
                      C Offline
                      Christianvs
                      wrote on last edited by Christianvs
                      #17

                      @sierdzio
                      Is there any downside to just calling this as parent?

                      @Pablo-J-Rogina
                      I actually cannot find where to mark it as solved
                      EDIT: Done! :)

                      sierdzioS 1 Reply Last reply
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                      • C Christianvs

                        @sierdzio
                        Is there any downside to just calling this as parent?

                        @Pablo-J-Rogina
                        I actually cannot find where to mark it as solved
                        EDIT: Done! :)

                        sierdzioS Offline
                        sierdzioS Offline
                        sierdzio
                        Moderators
                        wrote on last edited by
                        #18

                        @Christianvs said in Help with QTimer scope:

                        Is there any downside to just calling this as parent?

                        No. The other solution is worse, because it is easy to forget about calling delete. If you use Qt's parent-child system, then Qt will automatically delete objects when their parent is deleted.

                        There is a possibility that it is not the behaviour you want, but that is not something we can determine from the code above.

                        Other options for managing object life:

                        • QSharedPointer
                        • stl pointers

                        (Z(:^

                        1 Reply Last reply
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