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QList wrapper

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  • F firen
    25 Nov 2022, 18:25

    Hi,

    I would like to override QList.

    If I instantiate it for example with QString, I would write:

    QList<QString>

    and if I would like to use Pointer it would be

    QList<QString*>.

    So is there a chance that I could override QList, that an instantiation QList<QString> would work like QList<QString*>? I would ALWAYS like to store/work only with the pointers.

    Thanks!

    M Offline
    M Offline
    mpergand
    wrote on 25 Nov 2022, 18:58 last edited by mpergand
    #3

    @firen
    A template class ?

    template <class T>
    class PointerList : public QList<T*>
    {
        public:
                   PointerList() : QList<T*>() {}
                   ~PointerList()
                        {
                        qDeleteAll(this->begin(),this->end());
                        }
    
        private:
                 Q_DISABLE_COPY(PointerList)
    
    };
    
    F 1 Reply Last reply 26 Nov 2022, 12:23
    0
    • M mpergand
      25 Nov 2022, 18:58

      @firen
      A template class ?

      template <class T>
      class PointerList : public QList<T*>
      {
          public:
                     PointerList() : QList<T*>() {}
                     ~PointerList()
                          {
                          qDeleteAll(this->begin(),this->end());
                          }
      
          private:
                   Q_DISABLE_COPY(PointerList)
      
      };
      
      F Offline
      F Offline
      firen
      wrote on 26 Nov 2022, 12:23 last edited by firen
      #4

      @mpergand That was my idea as well but didn*t work. maybe I did something wrong. I will try again. :-)

      I read about Q_DISABLE_COPY. Isn`t it mainly for QObject based types?

      C M 2 Replies Last reply 26 Nov 2022, 12:35
      0
      • F firen
        26 Nov 2022, 12:23

        @mpergand That was my idea as well but didn*t work. maybe I did something wrong. I will try again. :-)

        I read about Q_DISABLE_COPY. Isn`t it mainly for QObject based types?

        C Offline
        C Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on 26 Nov 2022, 12:35 last edited by
        #5

        @firen said in QList wrapper:

        I read about Q_DISABLE_COPY. Isn`t it mainly for QObject based types?

        If you want to copy PointerList <T> then you have to provide a proper copy operator, the one generated by the compiler will not work, therefore Q_DISABLE_COPY.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
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        • F firen
          26 Nov 2022, 12:23

          @mpergand That was my idea as well but didn*t work. maybe I did something wrong. I will try again. :-)

          I read about Q_DISABLE_COPY. Isn`t it mainly for QObject based types?

          M Offline
          M Offline
          mpergand
          wrote on 26 Nov 2022, 13:48 last edited by
          #6

          @firen said in QList wrapper:

          That was my idea as well but didn*t work. maybe I did something wrong. I will try again. :-)

          Show your code.
          You must add dynamically allocated objects to the list, it seems obvious but maybe it needs to be said.

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          • F Offline
            F Offline
            firen
            wrote on 28 Nov 2022, 09:07 last edited by firen
            #7

            It looks like this now:

            template <class T>
            class CPtrListWrapper:
              public QList<T*>
            {
            
              using Item = T*;
            
            public:
              CPtrListWrapper():
                QList(),
                m_bAutoDelete(false),
                m_pCurrentItem(nullptr)
              {
                
              }
               
              ~CPtrListWrapper()
              {
            
              }
            
            //I need to wrap an old Containerclass and want to replace it internally by QList and these is one of the original methods
              void insert(uint i,
                const T* d) // 
              {
                QList::insert(i, d);
              }
            

            But this gives me an error C2664 if I try:

            bas::qtw::CPtrList<QString> m_q5List;
            const QString* pString = new QString("TEST");
            
            m_q5List.insert(0, pString);
            
            

            The error is that he cannot convert "const QString *" in "QString *const &"

            J 1 Reply Last reply 28 Nov 2022, 09:10
            0
            • F firen
              28 Nov 2022, 09:07

              It looks like this now:

              template <class T>
              class CPtrListWrapper:
                public QList<T*>
              {
              
                using Item = T*;
              
              public:
                CPtrListWrapper():
                  QList(),
                  m_bAutoDelete(false),
                  m_pCurrentItem(nullptr)
                {
                  
                }
                 
                ~CPtrListWrapper()
                {
              
                }
              
              //I need to wrap an old Containerclass and want to replace it internally by QList and these is one of the original methods
                void insert(uint i,
                  const T* d) // 
                {
                  QList::insert(i, d);
                }
              

              But this gives me an error C2664 if I try:

              bas::qtw::CPtrList<QString> m_q5List;
              const QString* pString = new QString("TEST");
              
              m_q5List.insert(0, pString);
              
              

              The error is that he cannot convert "const QString *" in "QString *const &"

              J Offline
              J Offline
              jsulm
              Lifetime Qt Champion
              wrote on 28 Nov 2022, 09:10 last edited by jsulm
              #8

              @firen said in QList wrapper:

              But this gives me an error C2664 if I try:

              Please post the whole error, not just its id.
              Also, show the declaration of m_q5List.

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

              F 1 Reply Last reply 28 Nov 2022, 09:13
              0
              • J jsulm
                28 Nov 2022, 09:10

                @firen said in QList wrapper:

                But this gives me an error C2664 if I try:

                Please post the whole error, not just its id.
                Also, show the declaration of m_q5List.

                F Offline
                F Offline
                firen
                wrote on 28 Nov 2022, 09:13 last edited by
                #9

                @jsulm I have edited the post.

                Thanks! :)

                J 1 Reply Last reply 28 Nov 2022, 09:26
                0
                • F firen
                  28 Nov 2022, 09:13

                  @jsulm I have edited the post.

                  Thanks! :)

                  J Offline
                  J Offline
                  JonB
                  wrote on 28 Nov 2022, 09:26 last edited by
                  #10
                  This post is deleted!
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                  • F Offline
                    F Offline
                    firen
                    wrote on 28 Nov 2022, 12:53 last edited by firen
                    #11
                    This post is deleted!
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                    • F Offline
                      F Offline
                      firen
                      wrote on 28 Nov 2022, 13:01 last edited by
                      #12
                      This post is deleted!
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                      • M Offline
                        M Offline
                        mpergand
                        wrote on 28 Nov 2022, 13:25 last edited by
                        #13
                            PointerList<QString> plist;
                            plist.append(new QString("World"));
                            plist.insert(0,new QString("Hello"));
                        
                            for(const QString* str : plist)
                                qDebug()<<*str;
                        

                        print:
                        "Hello"
                        "World"

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                        0

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                        28 Nov 2022, 13:01

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