[boost] Re: [variant, MPL] Is there a variant -> mpl sequence metafunction ?

From: Joaquin M Lopez Munoz (joaquin_at_[hidden])
Date: 2005-05-18 01:09:21

Larry Evans <cppljevans <at> cox-internet.com> writes:

> 
> On 05/17/2005 10:07 PM, Jaakko Järvi wrote:
> > make_variant_over<Seq>::type
> > 
> > creates a variant type from an MPL Sequence.
> > 
> > Is there an operation that would do the opposite, create an MPL sequence 
> > from a variant?
> > 
> > I cannot just use the type parameter list as such because the types that 
> > stand for an empty
> > type are different in both libraries: boost::detail::variant::void_ in 
> > variant, and something
> > else in MPL.
> I'd suggest making variant part of mpl.  With that, the problem
> disappears.  Also, variant and tuple are duals of each other, in
> category theory terms; hence, it would make sense if the implementations
> reflected this duality.  The code at:
> 
> http://cvs.sourceforge.net/viewcvs.py/boost-sandbox/boost-
sandbox/boost/indexed_set/?hideattic=0
> 
> is an intial attempt at exploiting this duality.
> 
> 
Aren't you referrring to

http://cvs.sourceforge.net/viewcvs.py/boost-sandbox/boost-
sandbox/boost/indexed_types/?hideattic=0

instead?

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo