RE: [boost] Re: Variant implementation change (was re: unions)finalsummary

From: Brock Peabody (brock.peabody_at_[hidden])
Date: 2003-10-09 15:46:34

> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]]
> On Behalf Of David Abrahams
> Sent: Thursday, October 09, 2003 3:19 PM
> To: boost_at_[hidden]
> Subject: [boost] Re: Variant implementation change (was re:
> unions)finalsummary
> 
> "Rainer Deyke" <rainerd_at_[hidden]> writes:
> 
> > Brock Peabody wrote:
> >> (5) If variant can be singular you will need an additional case for
> >> each variant and possibly turn many compile-time errors into run-time
> >> errors.
> >> This is a fact too.
> >
> > While trivially true, I doubt this is actually important in real code.
> If a
> > variant operation that only provides the basic guarantee throws, the
> state
> > of the variant is "valid" but undefined.
> 
> Not undefined, but unspecified.  There's a big difference.

Yes, and the point I was trying to make with (5) really has nothing to do
with exceptions anyway.  Making it so that variants can be singular
increases the complexity and chance for error in all code that uses
variants.

Brock