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Increasing usage for C++ new operators based on data model indexes?

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data modelscreateindexallocationnew operatorssoftware design
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  • E elfring

    Why do you think in this direction?

    kshegunovK Offline
    kshegunovK Offline
    kshegunov
    Moderators
    wrote on last edited by
    #54

    @elfring said in Increasing usage for C++ new operators based on data model indexes?:

    Why do you think in this direction?

    Experience.

    Read and abide by the Qt Code of Conduct

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    • kshegunovK kshegunov

      @elfring said in Increasing usage for C++ new operators based on data model indexes?:

      Why do you think in this direction?

      Experience.

      E Offline
      E Offline
      elfring
      wrote on last edited by
      #55

      Does your software development experience include the usage of placement new?

      VRoninV kshegunovK 2 Replies Last reply
      0
      • E elfring

        Does your software development experience include the usage of placement new?

        VRoninV Offline
        VRoninV Offline
        VRonin
        wrote on last edited by
        #56

        Does your software development experience include the usage of QAbstractItemModel?

        I wouldn't question @kshegunov 's abilities as he's firmly in the top tier of developers contributing on this forum.

        "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
        ~Napoleon Bonaparte

        On a crusade to banish setIndexWidget() from the holy land of Qt

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        • VRoninV VRonin

          Does your software development experience include the usage of QAbstractItemModel?

          I wouldn't question @kshegunov 's abilities as he's firmly in the top tier of developers contributing on this forum.

          E Offline
          E Offline
          elfring
          wrote on last edited by
          #57

          Does your software development experience include the usage of QAbstractItemModel?

          My knowledge is growing also in this software area.

          … he's firmly in the top tier of developers contributing on this forum.

          This is fine.

          Our experiences are varying in several areas, don't they?

          Understanding difficulties can happen then when someone (like me) dares to present special development ideas.

          VRoninV 1 Reply Last reply
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          • E elfring

            Does your software development experience include the usage of QAbstractItemModel?

            My knowledge is growing also in this software area.

            … he's firmly in the top tier of developers contributing on this forum.

            This is fine.

            Our experiences are varying in several areas, don't they?

            Understanding difficulties can happen then when someone (like me) dares to present special development ideas.

            VRoninV Offline
            VRoninV Offline
            VRonin
            wrote on last edited by
            #58

            @elfring said in Increasing usage for C++ new operators based on data model indexes?:

            Understanding difficulties can happen then when someone (like me) dares to present special development ideas.

            Sorry if it came out wrongly before, we are not against new development ideas at all, not on this forum and not in the Qt Project.

            I think what is clear from the discussion above is that nobody here can think of an elegant, efficient, functional and safe way to introduce the concept you suggest in the QAbstractItemModel (or any of its subclasses) interface.
            Having said that, you are correct by saying

            Our experiences are varying in several areas, don't they?

            So our point is, if you have an idea for an implementation then please go ahead and propose it to the community. I'd be very happy to participate in the review process of such an innovation as well as I might end up learning something new (punt not intended)

            "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
            ~Napoleon Bonaparte

            On a crusade to banish setIndexWidget() from the holy land of Qt

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            • VRoninV VRonin

              @elfring said in Increasing usage for C++ new operators based on data model indexes?:

              Understanding difficulties can happen then when someone (like me) dares to present special development ideas.

              Sorry if it came out wrongly before, we are not against new development ideas at all, not on this forum and not in the Qt Project.

              I think what is clear from the discussion above is that nobody here can think of an elegant, efficient, functional and safe way to introduce the concept you suggest in the QAbstractItemModel (or any of its subclasses) interface.
              Having said that, you are correct by saying

              Our experiences are varying in several areas, don't they?

              So our point is, if you have an idea for an implementation then please go ahead and propose it to the community. I'd be very happy to participate in the review process of such an innovation as well as I might end up learning something new (punt not intended)

              E Offline
              E Offline
              elfring
              wrote on last edited by
              #59

              …, if you have an idea for an implementation then please go ahead and propose it to the community.

              I guess that progress will depend on this basic clarification:
              Are you familiar with the usage of placement new?

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              • VRoninV Offline
                VRoninV Offline
                VRonin
                wrote on last edited by
                #60

                The project maintainers are seasoned (15-20 years experience) developers and are familiar with all aspects of standard C++ (especially its oldest parts like placement new).

                It's safe to assume a total mastery of the placement new concept by people reviewing code, don't worry

                "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                ~Napoleon Bonaparte

                On a crusade to banish setIndexWidget() from the holy land of Qt

                E 1 Reply Last reply
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                • VRoninV VRonin

                  The project maintainers are seasoned (15-20 years experience) developers and are familiar with all aspects of standard C++ (especially its oldest parts like placement new).

                  It's safe to assume a total mastery of the placement new concept by people reviewing code, don't worry

                  E Offline
                  E Offline
                  elfring
                  wrote on last edited by
                  #61

                  It's safe to assume a total mastery of the placement new concept by people reviewing code, don't worry

                  This information is very promising.

                  • Unfortunately, I could not extract corresponding indications of understanding for my proposal so far.
                  • How would you like to clarify a possible mapping from data model indexes to pointers further?
                  VRoninV sierdzioS 2 Replies Last reply
                  0
                  • E elfring

                    It's safe to assume a total mastery of the placement new concept by people reviewing code, don't worry

                    This information is very promising.

                    • Unfortunately, I could not extract corresponding indications of understanding for my proposal so far.
                    • How would you like to clarify a possible mapping from data model indexes to pointers further?
                    VRoninV Offline
                    VRoninV Offline
                    VRonin
                    wrote on last edited by
                    #62

                    @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                    How would you like to clarify a possible mapping from data model indexes to pointers further?

                    That's what we are asking you to propose.
                    We can't think of a way unfortunately

                    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                    ~Napoleon Bonaparte

                    On a crusade to banish setIndexWidget() from the holy land of Qt

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                    • VRoninV VRonin

                      @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                      How would you like to clarify a possible mapping from data model indexes to pointers further?

                      That's what we are asking you to propose.
                      We can't think of a way unfortunately

                      E Offline
                      E Offline
                      elfring
                      wrote on last edited by
                      #63

                      We can't think of a way unfortunately

                      Why do you stumble on limitations in your imaginations here?

                      J.HilkJ VRoninV 2 Replies Last reply
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                      • E elfring

                        It's safe to assume a total mastery of the placement new concept by people reviewing code, don't worry

                        This information is very promising.

                        • Unfortunately, I could not extract corresponding indications of understanding for my proposal so far.
                        • How would you like to clarify a possible mapping from data model indexes to pointers further?
                        sierdzioS Offline
                        sierdzioS Offline
                        sierdzio
                        Moderators
                        wrote on last edited by
                        #64

                        @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                        Unfortunately, I could not extract corresponding indications of understanding for my proposal so far.

                        Because you have not proposed anything. Show an API and it will be judged. Show a usage example of that API and it will help us know if the API is convenient. Measure with benchmark and we'll know if it improves performance.

                        Without concrete foundations, any idea can be argued endlessly without result.

                        (Z(:^

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                        • E elfring

                          We can't think of a way unfortunately

                          Why do you stumble on limitations in your imaginations here?

                          J.HilkJ Offline
                          J.HilkJ Offline
                          J.Hilk
                          Moderators
                          wrote on last edited by
                          #65

                          @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                          We can't think of a way unfortunately

                          Why do you stumble on limitations in your imaginations here?

                          I guess that will depend on this basic clarification:
                          Are you familiar with the usage of placement new?


                          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.

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                          • E elfring

                            We can't think of a way unfortunately

                            Why do you stumble on limitations in your imaginations here?

                            VRoninV Offline
                            VRoninV Offline
                            VRonin
                            wrote on last edited by VRonin
                            #66

                            @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                            Why do you stumble on limitations in your imaginations here?

                            Honestly I just think I'm not smart enough to get into this. It wouldn't be the first time. On the other hand I'd be really happy to see how it could be implemented so I could learn something new

                            "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                            ~Napoleon Bonaparte

                            On a crusade to banish setIndexWidget() from the holy land of Qt

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                            • sierdzioS sierdzio

                              @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                              Unfortunately, I could not extract corresponding indications of understanding for my proposal so far.

                              Because you have not proposed anything. Show an API and it will be judged. Show a usage example of that API and it will help us know if the API is convenient. Measure with benchmark and we'll know if it improves performance.

                              Without concrete foundations, any idea can be argued endlessly without result.

                              E Offline
                              E Offline
                              elfring
                              wrote on last edited by
                              #67

                              Show an API and it will be judged.

                              Can this application programming interface be just “placement new” (which got the parameters “row” and “column” passed)?

                              VRoninV 1 Reply Last reply
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                              • E elfring

                                Show an API and it will be judged.

                                Can this application programming interface be just “placement new” (which got the parameters “row” and “column” passed)?

                                VRoninV Offline
                                VRoninV Offline
                                VRonin
                                wrote on last edited by VRonin
                                #68

                                @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                                Can this application programming interface be just “placement new” (which got the parameters “row” and “column” passed)?

                                See, I struggle already, what would the return type be? (void* is a bit useless...)

                                "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                                ~Napoleon Bonaparte

                                On a crusade to banish setIndexWidget() from the holy land of Qt

                                E 1 Reply Last reply
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                                • VRoninV VRonin

                                  @elfring said in Increasing usage for C++ new operators based on data model indexes?:

                                  Can this application programming interface be just “placement new” (which got the parameters “row” and “column” passed)?

                                  See, I struggle already, what would the return type be? (void* is a bit useless...)

                                  E Offline
                                  E Offline
                                  elfring
                                  wrote on last edited by
                                  #69

                                  See, I struggle already, what would the return type be?

                                  C++ new operators are returning non-void-pointer types, don't they?

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                                  • VRoninV Offline
                                    VRoninV Offline
                                    VRonin
                                    wrote on last edited by
                                    #70

                                    I still can't see a way forward.
                                    The simplest example would probably be QStringListModel. Could you help me understand how the placement new operator would work in that case?

                                    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                                    ~Napoleon Bonaparte

                                    On a crusade to banish setIndexWidget() from the holy land of Qt

                                    E 1 Reply Last reply
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                                    • VRoninV VRonin

                                      I still can't see a way forward.
                                      The simplest example would probably be QStringListModel. Could you help me understand how the placement new operator would work in that case?

                                      E Offline
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                                      elfring
                                      wrote on last edited by
                                      #71

                                      Could you help me understand how the placement new operator would work in that case?

                                      Can you understand already that “placement new” provides a pointer to an existing object?

                                      VRoninV 1 Reply Last reply
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                                      • E elfring

                                        Could you help me understand how the placement new operator would work in that case?

                                        Can you understand already that “placement new” provides a pointer to an existing object?

                                        VRoninV Offline
                                        VRoninV Offline
                                        VRonin
                                        wrote on last edited by
                                        #72

                                        Yes, I can't see a safe way to use that pointer though

                                        "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                                        ~Napoleon Bonaparte

                                        On a crusade to banish setIndexWidget() from the holy land of Qt

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                                        • VRoninV VRonin

                                          Yes, I can't see a safe way to use that pointer though

                                          E Offline
                                          E Offline
                                          elfring
                                          wrote on last edited by
                                          #73

                                          Yes,

                                          I find this answer confusing in combination with the subsequent information.

                                          I can't see a safe way to use that pointer though

                                          You are used to the application of ordinary pointers.

                                          auto x(new my_ball);
                                          

                                          How many ball variants would you manage by your QStringListModel example?

                                          1 Reply Last reply
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