"David Abrahams" <dave@[...].com>  wrote in message
news:un0lswyue.fsf@[...]..
>  Hugo Duncan <hugoduncan@[...].net> writes:
> 
>  > I am trying to use MPL to generate code.
>  >
>  > I have a list of types, which I would like to use to call a template
>  > function with arguments that are not dependent on the list.
>  >
>  > eg
>  >
>  > given:
>  >   template <typename T> void my_function(std::string& s);
>  >   typedef list<int, float, double> my_list;
>  >   std::string s;
>  >
>  > what do I write using MPL to generate the equivalent of the following ?
>  >
>  >   my_function<int>(s);
>  >   my_function<float>(s);
>  >   my_function<double>(s);
> 
>  With the latest CVS, it would be something like this:
> 
>      struct func
>      {
>          func(std::string& s) : s(s) {}
> 
>          template <class T>
>          void operator()(T) const
>          {
>              my_function<T>(s);
>          }
> 
>       private:
>           std::string& s;
>      };
> 
>      mpl::for_each<my_list>(func(s));
> 
>  If you have any reference or array types in my_list, you might need to
>  do this instead:
> 
> 
>      struct func
>      {
>          func(std::string& s) : s(s) {}
> 
>          template <class T>
>          void operator()(mpl::identity<T>) const
>          {
>              my_function<T>(s);
>          }
> 
>       private:
>           std::string& s;
>      };
> 
>      mpl::for_each<my_list, mpl::make_identity<> >(func(s));

Or (barring my lack of mastering some syntactic details):

inline void do_my_function(string&, void_) {}

template <class Lst> 
inline void do_my_function(string& s, Lst lst)
{
    my_function<front<Lst> ::type>(s);
    do_my_function(s, pop_front<Lst> ::type());
}
...
do_my_function(s, my_list());

No struct, no for_each, no operator(). Et que le meilleur gagne :o).


Andrei



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