Re: [boost] How to convert a vector of base classes to template based code?

From: Peng Yu (pengyu.ut_at_[hidden])
Date: 2008-07-11 00:03:35

On Thu, Jul 10, 2008 at 2:47 AM, Sergei Politov <spolitov_at_[hidden]> wrote:
> Peng Yu <pengyu.ut <at> gmail.com> writes:
>
>>
>> The following program uses virtual functions. Essentially I need to go
> [skip]
>> }
>
>  Am I correctly understand that you are looking for something link this:
> ===================================================
> #include <iostream>
>
> #include <boost/fusion/algorithm.hpp>
> #include <boost/fusion/container.hpp>
>
> struct square {
>  void show_me() const {
>    std::cout << "square";
>  }
> };
>
> struct circle {
>  void show_me() const {
>    std::cout << "circle";
>  }
> };
>
> struct triangle {
>  void show_me() const {
>    std::cout << "triangle";
>  }
> };
>
> template<class T, class End>
> void out_pair(const T &, const End &, const End &) {}
>
> template<class T, class Begin, class End>
> void out_pair(const T & t, const Begin & begin, const End & end)
> {
>    t.show_me();
>    std::cout << " vs. ";
>    deref(begin).show_me();
>    std::cout << std::endl;
>    out_pair(t, next(begin), end);
> }
>
> template<class End>
> void out(const End &, const End &) {}
>
> template<class Begin, class End>
> void out(const Begin & begin, const End & end)
> {
>    out_pair(deref(begin), next(begin), end);
>    out(next(begin), end);
> }
>
> int main()
> {
>    typedef boost::fusion::vector<square, circle, square, triangle> Vec;
>    Vec v;
>    out(begin(v), end(v));
> }
> ===================================================
>
> Best Regards,
>  Sergei

Hi,

You understood me correctly. But it seems the transform from my code
to your code is a little complicated. Is there any more direct analog
between boost::fusion and the runtime algorithm. In particular, how to
directly use two iterations with the second iteration start with
something like it + 1 in my original code?

Thanks,
Peng