[boost] Re: variant questions

From: David Abrahams (dave_at_[hidden])
Date: 2003-09-02 06:44:55

"Eric Friedman" <ebf_at_[hidden]> writes:

> Alexander Nasonov wrote:
>> Eric Friedman wrote:
>> > If I understand you correctly, earlier versions of variant did precisely
>> > what you describe. Unfortunately, the "assumption" you make is false in
>> > general. See
> http://aspn.activestate.com/ASPN/Mail/Message/boost/1311813.
>> >
>> > Eric
>>
>> Well, is_polymorphic<T> based on compiler properties beyond the standrad.
>> Why not optimize variant for compilers which safely memcpy forth and back?
>
> I'm not sure how we would know... It seems to be a very bad idea to simply
> guess.

Don't guess.  Test on many platforms and enable the optimization where
possible.  FWIW, it's almost always possible.  I can't think of a
platform where it will fail.

> Plus, for compilers where it is in fact not allowed, we still need a
> workable, defined solution.

Absolutely.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com