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

From: David Abrahams (dave_at_[hidden])
Date: 2005-09-01 11:16:42

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.  So why are you saying there's a numerical representation
and a limit on # of types?

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