Re: [boost] Interest in switch generator

3 Feb 2007


      Steven Watanabe wrote:
...
AMDG
Is there any interest in a function template that generates a switch 
statement?
struct f {
    typedef void result_type;
    void operator()(mpl::int_<0>) const {
       std::cout << "2" << std::endl;
    }
    void operator()(mpl::int_<1>) const {
       std::cout << "1" << std::endl;
    }
    void operator()(mpl::int_<5>) const {
       std::cout << "0" << std::endl;
    }
};
int main() {
    typedef mpl::vector<mpl::int_<0>, mpl::int_<1>, mpl::int_<5> > cases;
    switch<cases>(5, f()); //prints 0
    try {
        switch<cases>(3, f());
    } catch(bad_switch&) {}
}
I'm interested. I'll need polymorphic return type handling though.
Something like:

struct f
{
     template <typename Case> struct result;

     template <> struct result<mpl::int_<0> >
         : mpl::identity<char> {};

     template <> struct result<mpl::int_<2> >
         : mpl::identity<float> {};

     template <> struct result<mpl::int_<5> >
         : mpl::identity<std::string> {};

     char operator()(mpl::int_<0>) const;
     float operator()(mpl::int_<1>) const;
     std::string operator()(mpl::int_<5>) const;
};

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net