Re: template class question

From:

Barry <dhb2000@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 31 May 2008 20:20:59 -0700 (PDT)

Message-ID:

<a052ddbb-13a5-4e00-b629-cde96e40d746@k30g2000hse.googlegroups.com>

On Jun 1, 5:56 am, girays <selcukgi...@gmail.com> wrote:

Hello everyone,

I have a simple problem what I don't know the exact syntac for this.
My code is shown below:

        enum LengthType
        {
                LENGTH_METER = 0,
                LENGTH_KMETER,
                LENGTH_YARD, // 1 yard = 0,914 me=

ter

LENGTH_KYARD
};

add conversion ratio template
template <LengthType fromType, LengthType toType>
struct ConvRatio;

template <>
struct ConvRatio <LENGTH_METER, LENGTH_KMETER>
{ enum { value = 1000 }; };
// if value is not always integer,
// use a static member function to return a float

// other conversion ratios go here ...

        template <LengthType L>
        class Length
        {
        public:
                Length(void);
                ~Length(void);

                // Length<toType> convertTo(LengthType toT=

ype) const; ???????

                 template <LengthType toType>
                 Length<toType> convertTo() const
                 { return m_value * ConvRatio<L, toType>::value; }

        private:
                LengthType m_type;
                float m_value;
        };

        template <LengthType L>
                Length<L>::Length( void )
                : m_type(L)
                , m_value()
        {
        }

You can see the lined marked ??????? at the end of line. I want to
convert from one Length object to another Length object. How can I
write this simple (may be not simple but I don't know how to do with
template code) code?

Suppose you have constructor
Length::Length(float);
and define your Length destruction;

Here is a test case:

int main()
{
  Length<LENGTH_METER> len1(15);
  Length<LENGTH_KMETER> len2 = len1.convertTo<LENGTH_KMETER>();
  //std::cout << len2 << std::endl; // need to friend the ostream
inserter
}

--
Best Ragards
Barry