template < class T > class XVector < T >
{
   ...
   template < class T > T
   XVector < T >::getIncrement ()
   {
       ...
   }
   template < class T > int
   XVector < T >::getValue (size_t index, T& value)
   {
      ...
      //The problematic line
      value = (T) (first_value + getIncrement())
                  * (long) (index - first_index);
      ....
   }
}

class TypeValue
{
    union
    {
        long* _int_value;
        double* _real_value;
        string* _text_value;
    } _value;

    TypeValue();
    explicit TypeValue(long _long);
    explicit TypeValue(int _int);
    explicit TypeValue(unsigned long _ulong);
    ...
    //similarly for all the remaining supported types.
    TypeValue(const TypeValue& ) //Copy constructor

    virtual TypeValue& operator=(const TypeValue &rhs);
    TypeValue& operator+ (TypeValue& )const;
    TypeValue& operator* (TypeValue& )const;
    ...
    //For all the basic operators

    operator long() const;
    operator int() const;
    operator unsigned long() const;
    operator unsigned int() const;
    ...

}

long [int]

operator long() const;

long ToLong() const;