On 9/1/05, David Abrahams <dave@boost-consulting.com> wrote:
Eric Niebler <eric@boost-consulting.com> 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.
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. Here, though, we have more information. In stead of using an integral number to 'register' a type, we can use the input type: template<typename InputType> struct msvc_extract_type { struct id2type; }; template<typename RegisteredType, typename InputType> struct msvc_register_type : msvc_typeof_base<InputType> { struct msvc_typeof_base<InputType>::id2type // This uses nice VC6-VC7 bugfeature { typedef RegisteredType type; }; }; Later: template<typename U> struct remove_pointer { template<typename T> msvc_register_type<T,remove_pointer<T*> > remove_ptr_fn(T* (*)()) static U test_function(); enum {register_type=sizeof(remove_ptr_fn(test_function))}; typedef typename msvc_extract_type<remove_pointer<U> >::id2type::type type; }; I'll try to get a version up and going with this implementation very soon. Regards, Peder
-- Dave Abrahams Boost Consulting www.boost-consulting.com
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