Proto for Boost mailing list page: Re: [proto] Thoughts on traversing proto expressions and reusing grammar

Subject: Re: [proto] Thoughts on traversing proto expressions and reusing grammar
From: Thomas Heller (thom.heller_at_[hidden])
Date: 2010-10-18 06:15:36

On Saturday 16 October 2010 04:10:23 Eric Niebler wrote:
> On Thu, Oct 14, 2010 at 10:46 PM, Thomas Heller
> 
> <thom.heller_at_[hidden]>wrote:
> > So, one of your points of criticism was that my solution was overly
> > verbose.
> > I like to throw this ball back at you. I think both solutions are quite
> > verbose. I guess verbosity is what it takes to get a solution meeting
> > the requirements.
> 
> You're right, my solution is verbose, too. The problem is the
> open-extensibility requirement. Proto::or_ is concise. The equivalent
> proto::switch_ is verbose. There aren't many constructs in C++ that are
> openly extensible. Namespaces, overload sets and template
> specializations. (Others?) Only template specializations fit the bill,
> and specializing a template takes a lot of typing. And if you want the
> set of transforms to be also openly extensible and independent of the
> grammars, that's twice the boilerplate. Seems unavoidable.
> 
> I'm interested in finding some nice wrapper that presents a cleaner
> interface. Maybe even macros could help.

Yes this i a hard problem to tackle.

Anyway ... i started the new prototype. I finished the core.
I added customization points for placeholders and terminals.
I have no time to explain what i have done so far. But want to share if you 
want to have a preview:
http://github.com/sithhell/boosties/tree/master/phoenix/

Will share more this evening.