Maurizio Vitale wrote:
Eric Niebler <eric@boost-consulting.com> writes:
What about introducing a macro:
#define BOOST_PROTO_WRAP(DOMAIN,EXPRESSION) \ [cut] 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
Maurizio Vitale wrote: 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.
Instead of the macro I was thinking about defining the generator inside my_domain. If the code is really always the same, it is not even necessary to define the complete generator, just the expression to wrap around proto expressions. I think where the wrapper is used, my_context is available.
If this is doable it would encapsulate the wrapper inside the domain, which is where it belongs.
This is now implemented. Proto::generate<> is gone. You now specify the expression generator as a template parameter to proto::domain. NOTE: the generator parameter comes first! The (optional) grammar parameter is now second. Also, there is a helper for adapting an expression wrapper to a generator. Given some expression wrapper: struct mydomain; template<typename Expr> struct myexpr : proto::extends<Expr, myexpr<Expr>, mydomain> ... You can specify the generator with: struct mydomain : proto::domain< proto::generator<myexpr> > {}; This change should loudly break any existing code that uses generators. Sorry for that. -- Eric Niebler Boost Consulting www.boost-consulting.com