Proto for Boost mailing list page: Re: [proto] Externalizing grammar pattern matching

Subject: Re: [proto] Externalizing grammar pattern matching
From: Eric Niebler (eric_at_[hidden])
Date: 2010-11-23 11:20:32

On 11/23/2010 10:19 AM, Joel Falcou wrote:
> So, question is: is there a way to have an extensible list of
> when<pattern,rule> that can be extended "from the outside", something
> like a proto::switch_ but with patterns instead of tag ?

No. The best you can do is document how to define a new Proto algorithm
from an old one:

  struct Old : proto::or_< ... > {};

  struct New : proto::or_< my_stuff, Old > {};

Now everywhere in your library that you have the Old algorithm
hard-coded, you need to make it a template parameter so that your stuff
can be used with an extended algorithm.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com