[boost] Re: Re: Proposal --- A type-safe union

From: Andrei Alexandrescu (andrewalex_at_[hidden])
Date: 2002-06-13 01:18:13

"Douglas Gregor" <gregod_at_[hidden]> wrote in message
news:200206130105.16819.gregod_at_cs.rpi.edu...
> I just don't see any axis along which there is a significant
variation with
> the use of variants where we would need a nontrivial policy.

I believe the same. The variant is quite a fundamental type with a
small and clear set of primitive operations. In particular, those
primitive operations ought to allow implementing higher level
operations.

For example, let's take various conversions. These can be nicely
implemented through visitation. So why not focus on developing a nice
visitation facility and then use it for all sorts of conversions?

What I also believe, in contradiction with some participants, is that
Variant should use typelists. If not, then Variant will factionally
develop its own little typelist facility (as some other libraries in
boost do today) and this doesn't work very nicely.

Andrei