[boost] Re: Proposal: configurable tuple arity limit

From: David Abrahams (dave_at_[hidden])
Date: 2004-02-16 09:52:46

"Max Motovilov" <max_at_[hidden]> writes:

> I may have posted something to this effect in Apr. 2003 but got no
> response if I have; just thought I might have better luck the second time as
> there
> were no changes to the tuple library since then.
>
> Proposal: current boost/tuple library has a hardcoded limit on the tuple
> arity (10 elements). Some applications may require substantially larger
> tuples even at a cost of extended compilation time. Using boost/preprocessor
> library, it is relatively easy to rewrite the tuple code in such a way that
> arity limit will depend on a single configuration macro without incuring any
> other changes to the library. No additional cost will be imposed on the
> users who are satisifed with the current tuple library.
>
> I have a working implementation of such configurable tuples that I've been
> using since Apr. 2003. As I had no need to support C++ compilers that do not
> implement partial specification, I have only converted
> boost/tuple/detail/tuple_basic.hpp so far. Arity limit is controlled by the
> BOOST_TUPLE_MAX_ARITY macro which is defaulted to 10 inside tuple_basic.hpp
> if it is not defined prior to its inclusion. Since I am not sure what
> procedure should I follow to submit such a modification to an existing Boost
> library, I decided just to post the proposal here and provide a link to the
> modifed file: http://fridge.yymap.com/files/tuple_basic.hpp

The existing tuple implementation is scheduled to be replaced in
Boost 1.32.0 by Joel de Guzman's "Fusion" library.  See
http://boost-consulting.com/boost/boost/spirit/fusion/

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com