Re: [boost] [proto] macro for wrapping expressions

From: Eric Niebler (eric_at_[hidden])
Date: 2007-05-15 19:29:17

Maurizio Vitale wrote:
> What about introducing a macro:
> 
> #define BOOST_PROTO_WRAP(DOMAIN,EXPRESSION)                           \
> namespace boost { namespace proto {                                   \
>     template<typename E>                                              \
>     struct generate<DOMAIN, E> {                                      \
>       typedef EXPRESSION<E> type;                                     \
>       static type make (E const& expr) {                              \
>         return type (expr);                                           \
>       }                                                               \
>     };                                                                \
> } } 
> 
> as far as I can tell one does never need something different from the above boilerplate code.
> (otherwise I'd like to see examples, for my own education)
> 
> Not a big deal, I know, but looks nicer (and sound nicer in the docs as well, I think).

I agree, this part of proto isn't as nice as it could be. I've 
considered making the expression generator a template parameter to the 
proto::domain, something like:

struct my_domain
   : proto::domain< struct my_grammar, struct my_generator >
{};

This way, you wouldn't have to open proto's namespace to specialize 
proto::generate. I haven't thought too hard about it, though. I do know 
that I would like to avoid macros in proto's interface as much as possible.

> Have fun in Colorado!

Workin' on it! :-)

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com