[boost] Variant Library: copy constructible requirements

From: Gennadiy Rozental (gennadiy.rozental_at_[hidden])
Date: 2003-04-02 01:50:40

> > 3. Copy Constructible/Assignable requirements on bounded types
> > This only need to be required if variant should have appropriate
> > feature.
>
> I disagree. As-is, every variant object requires CopyConstructible
> bounded types, as it is the only way to construct its content.
>
> Some notes, however. I may be able to eliminate the Assignable
> requirement altogether by modifying the implementation of
> variant::swap. As well, there has been some discussion about in-place
> construction, which could eliminate the CopyConstructible requirement
> except in cases of actual variant copying. (This conversation occurred
> with regard to optional, but could work with equal applicability to
> variant.)

 I think it's the way to go. This implementation issue shouldn't affect
overall design. It would be a pity if we couldn't use variant for
noncopyable types.

Gennadiy.