Re: [boost] Is there a macro to test ifstd::numerc_limits<>::max_digits10 is supported by a platform?

Subject: Re: [boost] Is there a macro to test ifstd::numerc_limits<>::max_digits10 is supported by a platform?
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2012-06-14 08:26:20

> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]] On Behalf Of John
> Maddock
> Sent: Thursday, June 14, 2012 12:14 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] Is there a macro to test ifstd::numerc_limits<>::max_digits10 is supported by
a
> platform?
> 
> >A proposed (but not reverted) fix for
> >
> > Trac #5758: Boost.Test Floating-point comparison diagnostic output
> > does not support radix 10
> >
> >        if( std::numeric_limits<T>::is_specialized &&
> > std::numeric_limits<T>::radix == 10 )
> >            ostr.precision( 2 + std::numeric_limits<T>::max_digits10);
> >            // Assume that max_digits10 is provided for all radix 10 as
> > they are quite new,
> >            // and anyway Kahan formula will not work for decimal.
> >
> > has caused trouble on platforms that do not yet support
> >
> > std::numeric_limits<T>::max_digits10
> >
> > We need a macro perhaps BOOST_NO_NUMERIC_LIMITS_ MAX_DIGITS10
> >
> > that will prevent the compiler seeing this code if max_digits10 is not
> > supported.
> 
> Try BOOST_NO_NUMERIC_LIMITS_LOWEST as a proxy?

OK, but I'm on holiday for a while so I'll wait until I get back before I create more trouble ;-)

Anyone trying multiprecision and wanting this feature can patch their
\boost-trunk\boost\test\tools\impl.hpp locally.

Thanks

Paul

---
Paul A. Bristow,
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[phone]  07714330204
pbristow_at_[hidden]