Re: [boost] Re: Variant implementation change (wasre:unions)finalsummary

From: E. Gladyshev (egladysh_at_[hidden])
Date: 2003-10-09 21:51:09

--- Eric Friedman <ebf_at_[hidden]> wrote:
> brock wrote:
> [snip]
> > There are a lot of disadvantages in allowing variants to be singular at any
> > time.  We've been all over this.  But if we say they can be singular only
> > after a failed assignment, then you can pretty safely ignore the possibility
> > in most of your code...  I think.  I wonder what Eric and Dave think of this
> > or if they finally got tired of all the noise and tuned out :)  Maybe this
> > is noise too :)
> 
> I've suggested it before.
> 
> See http://aspn.activestate.com/ASPN/Mail/Message/boost/1831995.
> 
>  From an implementation standpoint, there is no problem at all with 
> singular variants; I can code variant so that it destroys itself 
> properly even when in a singular state. As well, since assignment to a 
> singular variant is a meaningful operation, it is possible to "restore" 
> a singular variant to full-status. However, visitation of a singular 
> variant is *not* a meaningful operation in anyway and should be left 
> undefined.
> 
> Given that singular variants will *only occur in the wake of failed 
> assignment*, this may not be a problem. Allowing the possibility of 
> singular variants at all, however, does represent a departure from where 
> variant has been in the past. Before I make a change like this, I would 
> appreciate some sort of consent from the community. So far, this has 
> been significantly lacking.
> 

You know *my* point of view and rationale.
I am strongly for singular variant for now.
The better option is strong guarantees
but the discussion about it is still underway.

Thanks again for the last changes!

Eugene

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