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

From: David Abrahams (dave_at_[hidden])
Date: 2005-09-01 09:37:16

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.

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