Providing a record source

1. Define the record source using TRecordSource.
   
2. Define the handle class to be used by client applications using TRecordSourceHandle.
   

Begin by defining the record source:

  class TFibonacciRecordSource : public TRecordSource
  {
  protected:
      TFibonacciRecordSource() : fCurrent(0), fNext(1) {}
      ELength GetRecordCount(long&) const
          {return TRecordSourceHandle::kInfinite;}
      ELength GetRecordsRemaining(long&) const
          {return TRecordSourceHandle::kInfinite;}
      long GetColumnCount() const {return 1;}
      long GetColumnTitle(TText title, ColumnPosition)
          {title.Replace("Fibonacci");}
      EColumnType GetColumnType(ColumnPosition)
          {return TRecordSourceHandle::kLong;}
      Boolean GetField(long& value, ColumnPosition) const
          {value = fCurrent;}
      Boolean FetchRecord()
          {   long value = fCurrent + fNext;
              fCurrent = fNext;
              fNext = value;
              return TRUE;
          }
  private:
      long fCurrent;
      long fNext;
      friend class TFibonacciRecordSourceHandle;
  };

  class TFibonacciRecordSourceHandle : public TRecordSourceHandle
  {
  public:
      TFibonacciRecordSourceHandle()
          : TRecordSourceHandle(* new TFibonacciRecordSource);
  };

{ TFibonacciRecordSourceHandle fibonacci; long value; while (fibonacci.FetchRecord()) { GetField(value, 1); cout << value << ", "; } }