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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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  • kshegunovK kshegunov

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

    My proposal can eventually grow into another template library, can't it?

    Only if you write the library, or at least the core of it.

    The desired implementation can evolve further if the required concepts will be generally accepted.

    The only thing that's going to be generally accepted is written code, i.e. an implementation. Since you have written none, none is going to evolve.

    E Offline
    E Offline
    elfring
    wrote on last edited by
    #102

    The only thing that's going to be generally accepted is written code, i.e. an implementation.

    Some software designers expect the development of specific concepts before concrete programming.
    Template programming can help to achieve a safer coding style.

    JKSHJ 1 Reply Last reply
    0
    • E elfring

      The only thing that's going to be generally accepted is written code, i.e. an implementation.

      Some software designers expect the development of specific concepts before concrete programming.
      Template programming can help to achieve a safer coding style.

      JKSHJ Offline
      JKSHJ Offline
      JKSH
      Moderators
      wrote on last edited by
      #103

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

      Some software designers expect the development of specific concepts before concrete programming.

      @elfring, discussing "specific concepts" with you is difficult because your posts are unclear. If you write code, then your ideas will be clearer and easier to understand.

      Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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      • JKSHJ JKSH

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

        Some software designers expect the development of specific concepts before concrete programming.

        @elfring, discussing "specific concepts" with you is difficult because your posts are unclear. If you write code, then your ideas will be clearer and easier to understand.

        E Offline
        E Offline
        elfring
        wrote on last edited by
        #104

        discussing "specific concepts" with you is difficult because your posts are unclear.

        I hope that the involved communication difficulties can be resolved after a bit more time.

        If you write code, then your ideas will be clearer and easier to understand.

        • Can your desire for “source code” distract from the really relevant functional design?
        • Can other information presentation variants and communication tools help more to achieve also a better common understanding?
        kshegunovK 1 Reply Last reply
        -1
        • E elfring

          discussing "specific concepts" with you is difficult because your posts are unclear.

          I hope that the involved communication difficulties can be resolved after a bit more time.

          If you write code, then your ideas will be clearer and easier to understand.

          • Can your desire for “source code” distract from the really relevant functional design?
          • Can other information presentation variants and communication tools help more to achieve also a better common understanding?
          kshegunovK Offline
          kshegunovK Offline
          kshegunov
          Moderators
          wrote on last edited by kshegunov
          #105

          I'll take the liberty to answer instead of @JKSH.

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

          I hope that the involved communication difficulties can be resolved after a bit more time.

          Your hopes are falling short. If you don't make an effort to provide what is required for a conversation, then the conversation is nonexistent. You don't. You don't answer questions, you don't in any way try to give back what was asked for, and you randomly pick up parts of the sentences to try and extend this thread.

          Can your desire for “source code” distract from the really relevant functional design?

          It can't. Source code is the product of thought in this community. Arguing excessively and arguing against providing source code is not going to work. We want to see you're serious enough about your claim that you're willing to put an effort in defending it. Empty platitudes and (semi)random links to documentation(s) are not going to be entertained.

          Can other information presentation variants and communication tools help more to achieve also a better common understanding?

          Common understanding is a two-way street. If you're not willing to meet us halfway I see no reason any of us to want to waste our time.

          Read and abide by the Qt Code of Conduct

          E 1 Reply Last reply
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          • kshegunovK kshegunov

            I'll take the liberty to answer instead of @JKSH.

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

            I hope that the involved communication difficulties can be resolved after a bit more time.

            Your hopes are falling short. If you don't make an effort to provide what is required for a conversation, then the conversation is nonexistent. You don't. You don't answer questions, you don't in any way try to give back what was asked for, and you randomly pick up parts of the sentences to try and extend this thread.

            Can your desire for “source code” distract from the really relevant functional design?

            It can't. Source code is the product of thought in this community. Arguing excessively and arguing against providing source code is not going to work. We want to see you're serious enough about your claim that you're willing to put an effort in defending it. Empty platitudes and (semi)random links to documentation(s) are not going to be entertained.

            Can other information presentation variants and communication tools help more to achieve also a better common understanding?

            Common understanding is a two-way street. If you're not willing to meet us halfway I see no reason any of us to want to waste our time.

            E Offline
            E Offline
            elfring
            wrote on last edited by
            #106

            You don't answer questions,

            I find this information inappropriate.

            you don't in any way try to give back what was asked for, …

            I chose to respond in different ways.

            Arguing excessively and arguing against providing source code is not going to work.

            • Are there any developers around who can clarify design extensions without thinking only in source code?
            • Can the original development idea become more interesting?

            Common understanding is a two-way street.

            Can the clarification of design aspects from a function template declaration help here?

            kshegunovK 1 Reply Last reply
            0
            • E elfring

              You don't answer questions,

              I find this information inappropriate.

              you don't in any way try to give back what was asked for, …

              I chose to respond in different ways.

              Arguing excessively and arguing against providing source code is not going to work.

              • Are there any developers around who can clarify design extensions without thinking only in source code?
              • Can the original development idea become more interesting?

              Common understanding is a two-way street.

              Can the clarification of design aspects from a function template declaration help here?

              kshegunovK Offline
              kshegunovK Offline
              kshegunov
              Moderators
              wrote on last edited by
              #107

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

              I find this information inappropriate.

              Yeah, me too.

              I chose to respond in different ways.

              Yeah, me too.

              • Are there any developers around who can clarify design extensions without thinking only in source code?

              We don't think only in source code, but we find it as a useful way to clarify what we mean. Are you able to clarify your design extensions through source code?

              • Can the original development idea become more interesting?

              Not unless you make it more interesting by including some source that we can discuss.

              Can the clarification of design aspects from a function template declaration help here?

              Nope, but a class with its function bodies would help.

              Read and abide by the Qt Code of Conduct

              E 1 Reply Last reply
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              • kshegunovK kshegunov

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

                I find this information inappropriate.

                Yeah, me too.

                I chose to respond in different ways.

                Yeah, me too.

                • Are there any developers around who can clarify design extensions without thinking only in source code?

                We don't think only in source code, but we find it as a useful way to clarify what we mean. Are you able to clarify your design extensions through source code?

                • Can the original development idea become more interesting?

                Not unless you make it more interesting by including some source that we can discuss.

                Can the clarification of design aspects from a function template declaration help here?

                Nope, but a class with its function bodies would help.

                E Offline
                E Offline
                elfring
                wrote on last edited by
                #108

                Are you able to clarify your design extensions through source code?

                My published software development activities demonstrate that such contributions can happen.

                Not unless you make it more interesting by including some source that we can discuss.

                How will your interests evolve for application programming interfaces expressed in the format of function template declarations?

                Nope, but a class with its function bodies would help.

                Can it occasionally be more helpful to clarify software design properties before attempting a specific implementation?

                kshegunovK 1 Reply Last reply
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                • E elfring

                  Are you able to clarify your design extensions through source code?

                  My published software development activities demonstrate that such contributions can happen.

                  Not unless you make it more interesting by including some source that we can discuss.

                  How will your interests evolve for application programming interfaces expressed in the format of function template declarations?

                  Nope, but a class with its function bodies would help.

                  Can it occasionally be more helpful to clarify software design properties before attempting a specific implementation?

                  kshegunovK Offline
                  kshegunovK Offline
                  kshegunov
                  Moderators
                  wrote on last edited by
                  #109

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

                  My published software development activities demonstrate that such contributions can happen.

                  Not from what I was able to see.

                  How will your interests evolve for application programming interfaces expressed in the format of function template declarations?

                  They will not. My interests have evolved already and in their current state of evolution they require hard facts, evidence if you will.

                  Can it occasionally be more helpful to clarify software design properties before attempting a specific implementation?

                  Occasionally it can, but not in this case.

                  Read and abide by the Qt Code of Conduct

                  E 1 Reply Last reply
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                  • kshegunovK kshegunov

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

                    My published software development activities demonstrate that such contributions can happen.

                    Not from what I was able to see.

                    How will your interests evolve for application programming interfaces expressed in the format of function template declarations?

                    They will not. My interests have evolved already and in their current state of evolution they require hard facts, evidence if you will.

                    Can it occasionally be more helpful to clarify software design properties before attempting a specific implementation?

                    Occasionally it can, but not in this case.

                    E Offline
                    E Offline
                    elfring
                    wrote on last edited by elfring
                    #110

                    They will not.

                    Can this kind of feedback express another kind of change resistance?

                    Occasionally it can,

                    It is nice that you can follow this view to some degree.

                    but not in this case.

                    I prefer a stricter separation between a software design draft and a possible prototype implementation here.

                    kshegunovK 1 Reply Last reply
                    0
                    • E elfring

                      They will not.

                      Can this kind of feedback express another kind of change resistance?

                      Occasionally it can,

                      It is nice that you can follow this view to some degree.

                      but not in this case.

                      I prefer a stricter separation between a software design draft and a possible prototype implementation here.

                      kshegunovK Offline
                      kshegunovK Offline
                      kshegunov
                      Moderators
                      wrote on last edited by
                      #111

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

                      Can this kind of feedback express another kind of change resistance?

                      I don't resist change. You have not proposed a change but a hypothesis, it's yet to be proven if it can be made into a change.

                      I prefer a stricter separation between a software design draft and a possible prototype implementation here.

                      That's your prerogative, just don't expect people to write the code for you.

                      Read and abide by the Qt Code of Conduct

                      1 Reply Last reply
                      1
                      • VRoninV Offline
                        VRoninV Offline
                        VRonin
                        wrote on last edited by
                        #112

                        Since we didn't make it explicit so far: we think your idea is really, really, bad. We tried to explain you why it's bad but you either decided to ignore us or just don't understand models enough to see the faults.

                        Proposing useful extensions is one thing, making us waste time discussing changes that are so bad they would get shot out in the first code review stage is another

                        "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

                          Since we didn't make it explicit so far: we think your idea is really, really, bad. We tried to explain you why it's bad but you either decided to ignore us or just don't understand models enough to see the faults.

                          Proposing useful extensions is one thing, making us waste time discussing changes that are so bad they would get shot out in the first code review stage is another

                          E Offline
                          E Offline
                          elfring
                          wrote on last edited by
                          #113

                          we think your idea is really, really, bad.

                          So it seems that we stumble on a conflict because of varying imaginations for further software evolution.
                          Our ways of thinking about software design aspects are generally different.

                          I am curious if any other Qt user or contributor would like to adjust the mentioned design details any more.

                          1 Reply Last reply
                          0
                          • VRoninV Offline
                            VRoninV Offline
                            VRonin
                            wrote on last edited by
                            #114

                            Ok, let's start a vote.

                            Anybody here thinks the design "proposed" above has any reason to exist?

                            "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

                            kshegunovK 1 Reply Last reply
                            0
                            • VRoninV VRonin

                              Ok, let's start a vote.

                              Anybody here thinks the design "proposed" above has any reason to exist?

                              kshegunovK Offline
                              kshegunovK Offline
                              kshegunov
                              Moderators
                              wrote on last edited by kshegunov
                              #115

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

                              Ok, let's start a vote.

                              Fine, I'll bite.

                              Anybody here thinks the design "proposed" above has any reason to exist?

                              No due to the "design" not having addressed all any of the issues raised in this thread. Being incomplete and practically inapplicable, which is my beef with it, makes the proposition more of a theoretical hypothesizing than a design proposition. Here's what is to be done, so to have it considered as a proposition for a change:

                              1. Motivation:
                                • There's no clear distinction why this change is needed. The QModelIndex class is already very light and can be passed around by value extremely cheaply. Why would introducing a heap manager be better.
                              2. Structure & design
                                • There's no clear way to tell how the memory management is to be done - the placement new requires a memory block to begin with. What class and how is going to manage the memory blocks throughout the application and how?
                                • There's no clarity how the interface between Qt code and user code is going to work.
                                  • Templates with QObjects is not an option, and deriving from QObject is necessary to have signal-slots.
                                  • Templates with models means making promises about binary and source compatibility hell. The API would define the private internals of the class and once set there's no going back to fix it for a period of a major version turnaround. (Notable warnings in the documentation that the containers should not be subclassed!)
                                  • Even if we assume the above is solved instantiation of the models will make binaries extremely fat.
                                  • Templates are distinct types, so QAbstractItemModel<MyType> is different from QAbstractItemModel<YourType>. Only way to solve is to have an interface (purely abstract class) that is to be referred in the user code. Possible, but hardly worth it; the vtables are going to get enormous.
                                  • Above statement also implies that the views have to be templated, as they have no notion of the user type until an instantiation of the model happens, which is in the user code. Practicality goes out the window.
                              3. Implementation
                                • No implementation provided.
                                • The sheer amount of changes needed means that basically half the Qt toolkit needs to be reimplemented.

                              Read and abide by the Qt Code of Conduct

                              1 Reply Last reply
                              6
                              • VRoninV Offline
                                VRoninV Offline
                                VRonin
                                wrote on last edited by VRonin
                                #116

                                Of course I'll cast my -1 vote as well.

                                I'll add to point 1:

                                • If the data contained in the model is all of basic types or implicitly shared types then it's possible to already use the current framework without ever triggering any expensive* copy

                                , to point 2:

                                • There's no clarity on how to support different types in different roles
                                  • would we need an additional template argument for each used role beyond Qt::UserRole? is so the problems above grow exponentially with the roles

                                And to point 3:

                                • No possible implementation for a reliable dataChanged emission if model internals are exposed directly

                                *expensive = a copy that implies more that a:

                                • memcpy of less than 65bits and
                                • an increase/decrease of a numeric reference counter

                                "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

                                1 Reply Last reply
                                3

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