具有非 void 返回类型的虚函数

考虑以下继承和组合方案。

示例程序

#include <iostream>
#include <valarray>
using namespace std;
class TapProcessing
{
    public:
          TapProcessing(){};
          virtual ~TapProcessing(){};
          virtual void getWeights(valarray<double> &weights) {};
          virtual void getPrecisionWeights (valarray<double> &precWeights) {};
          virtual const uint &getTapIndex(const uint index) const
          {
              valarray<uint> a;
              a.resize(10);
              return a[index];
          }; //const {return 0;};
          virtual const uint &getTapIndexLow(const uint index) const
          {
              valarray<uint> a;
              a.resize(10);
              return a[index];
          }; //const {return 0;};;
          virtual const uint &getTapIndexHigh(const uint index) const
          {
              valarray<uint> a;
              a.resize(10);
              return a[index];
          }; //const {return 0;};
};
class StepPrecisionTapProcessing : public TapProcessing
{
    public:
        StepPrecisionTapProcessing() { _tapIndex.resize(10, 3); }
        ~StepPrecisionTapProcessing() {};
        void getWeights(valarray<double> &weights) { return weights.resize(10);}
        virtual const uint &getTapIndex(const uint index) const {return _tapIndex[index]; }
    private:
          valarray<uint> _tapIndex;
};
class HighPrecisionTapProcessing : public TapProcessing
{
    public:
        HighPrecisionTapProcessing()
        {
            _tapIndexLow.resize(10, 4);
            _tapIndexHigh.resize(10, 5);
        }
        ~HighPrecisionTapProcessing() {};
        void getPrecisionWeights (valarray<double> &precWeights) { return precWeights.resize(10); };
        virtual const uint &getTapIndexLow(const uint index) const {return _tapIndexLow[index]; }
        virtual const uint &getTapIndeHigh(const uint index) const {return _tapIndexHigh[index]; }
    private:
          valarray<uint> _tapIndexLow;
          valarray<uint> _tapIndexHigh;
};
class Generator
{
    public:
           Generator(bool isPrecision)
           {
               if (isPrecision) {_tp = new HighPrecisionTapProcessing();
               }
               else { _tp = new StepPrecisionTapProcessing(); }
           }
           ~Generator() { delete _tp; }
           const uint &getTapIndex(const uint index) const {return _tp->getTapIndex(index); }
           const uint &getTapIndexLow(const uint index) const {return _tp->getTapIndexLow(index); }
           const uint &getTapIndexHigh(const uint index) const {return _tp->getTapIndexHigh(index); }
    private:
           TapProcessing *_tp;
};

int main()
{
  Generator *G = new Generator(true);
  uint index = 5;
  cout<<"High tap index is = "<<G->getTapIndexHigh(index)<<endl;
  delete G;
  return 0;
}

当我运行main时，我得到以下输出，

高抽头指数为 = 0

在这里，如果派生类中 getTapIndeHigh 的声明覆盖了基类中的声明，我们将在输出中看到值 5 而不是 0。为什么派生类实现不覆盖非空虚方法的类方法的基数？