Re: [boost] variadic template proto (was Re: [proto] design of expr<>

From: Eric Niebler (eric_at_[hidden])
Date: 2008-03-10 19:11:57

Larry Evans wrote:
> The args.hpp code here:
> 
> http://svn.boost.org/trac/boost/browser/branches/proto/v3/boost/xpressive/proto/args.hpp
> 
> around line 61 contains:
> 
<snip>
> 
> I don't understand why BOOST_PP_ENUM_PARMS is used in the same statement 
> as Args....  AFAICT, the BOOST_PP_ENUM_PARMS should be used when #undef 
> BOOST_HAS_VARIADIC_TMPL and the Args... when #define 
> BOOST_HAS_VARIADIC_TMPL.
> 
> Am I missing something?

It uses the preprocessor to do loop unrolling. It was an effort to bring 
compile times under control by reducing the number of template 
instantiations.

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