Re: [boost] which tag dispatch convention to use

From: Stjepan Rajko (stipe_at_[hidden])
Date: 2007-10-19 13:06:24

Ping?  Anyone?  I'd be very grateful for any advice...

On 10/15/07, Stjepan Rajko <stipe_at_[hidden]> wrote:
> Hello,
>
> As I'm preparing the dataflow library for submission (a.k.a. signal
> network gsoc project), I'm revisiting some of the design choices.
> Since I'm not too experienced with generic library design, I was
> wondering if anyone would share some advice on which tag dispatch
> convention to use.
>
> For my specializable functions, I adapted what is used in fusion, e.g.:
>
> template<typename ProducerTag, ConsumerTag>
> struct operation_impl;
>
> template<>
> struct operation_impl<some_producer_tag, some_consumer_tag>
> {
>   template<typename P, typename C>
>   struct apply
>   {
>       typedef some_result_type type;
>
>       static type call(P &p, C &c)
>       {
>         ...
>       }
>   };
> };
>
> and then free function `operation` extracts the tags from its
> arguments, calls operation_impl, and returns the result.
>
> Could someone tell me what the advantages/disadvantages of this
> approach are compared to, say,
>
> template<>
> struct operation_impl<some_producer_tag, some_consumer_tag>
> {
>   // specify result type using result_type typedef or template<> struct result
>   // ...
>
>   template<typename P, typename C>
>   some_result_type operator()(P &p, C &c)
>   {
>     ...
>   };
> };
>
> , or the technique described in:
> http://www.boost.org/more/generic_programming.html,
>
> or any other tag dispatching convention I should be aware of?
>
> Thanks in advance!
>
> Stjepan
>