Re: [boost] New implementation of remove_xxx for vintage compilers

From: Peder Holt (peder.holt_at_[hidden])
Date: 2005-09-02 00:48:17

On 9/1/05, David Abrahams <dave_at_[hidden]> wrote:
> David Abrahams <dave_at_[hidden]> writes:
> 
> > Peder Holt <peder.holt_at_[hidden]> writes:
> >
> >> On 9/1/05, David Abrahams <dave_at_[hidden]> wrote:
> >>> Eric Niebler <eric_at_[hidden]> writes:
> >>>
> >>> > Ah. But the fact remains that remove_pointer et al. are indeed broken on
> >>> > VC6 and VC7, and the regression tests bear this out.
> >>> >
> >>> > http://tinyurl.com/8fs7w
> >>> >
> >>> > IMO, the best path is to preserve the meaning of
> >>> > BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION for compilers without
> >>> > PTS. That is, it still defines full specializations of the type traits
> >>> > templates. But the typeof implementation should be what the primary
> >>> > template uses for compilers without PTS. That way, everything that is
> >>> > working now, keeps working with no change in performance.
> >>>
> >>> I think it would better to do some actual speed testing there.  After
> >>> all, using the typeof hack *could* turn out to be much faster and use
> >>> fewer resources than doing it the other way.
> >>>
> >>> It's a pretty easy test.
> >>
> >> I don't think using the typeof library directly is the best idea. When
> >> using typeof, you represent each type by a number, limiting you to
> >> ~1000 types.
> >
> > I hope that's false, but in any case, you've completely missed the
> > point.  There's a bugfeature in vc <= 7.1 that allows typeof to be
> > implemented without any such limitation.  No numerical representation
> > is ever generated.
> 
> Whoops; I read too fast, sorry.  You obviously know about the
> bugfeature. 

...I would think so.
Igor' Chesnokov's trick only applies to VC6.5 and VC7.1.
I implemented the trick used for VC7.0 :)

 So why are you saying there's a numerical representation
> and a limit on # of types?
> 
> --
> Dave Abrahams
> Boost Consulting
> www.boost-consulting.com
> 
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