Re: [Boost-users] Ann: Floating Point Utilities Review starts today

From: Pfligersdorffer, Christian (Christian.Pfligersdorffer_at_[hidden])
Date: 2008-02-21 04:54:29

Hello all,

we use fp_utilities in our portable binary archive implementation to
serialize floating point numbers. For doing so we found the functions
fp_traits<T>_impl::get_bits() and set_bits() to be exactly what we need.
In combination with Beman Dawes endian library we're able to transfer
binary data between ppc-32 and x86-32 reliably. This might serve as a
usecase since John Maddock pointed out serialization as a prominent
application of the library.

/**
 * save floating point types
 * 
 * We simply rely on fp_traits to extract the bit pattern into an
(unsigned)
 * integral type and store that into the stream.
 *
 * \todo treat nan values using fp_classify
 */
template <typename T>
BOOST_DEDUCED_TYPENAME boost::enable_if<boost::is_floating_point<T>
>::type
save(const T & t, dummy<3> = 0)
{
        using namespace boost::math::detail;
        BOOST_DEDUCED_TYPENAME fp_traits<T>::type::bits bits;
        fp_traits<T>::type::get_bits(t, bits);
        save(bits);
}

As you can see our code depends on functions that apparently are not
part of the public interface and I wonder why. Perhaps I overlooked
something? Those interested in the full code can find it in the boost
vault.

To sum it up: We think the fp_utilities provide useful functionality and
our tests indicate reliability that can be counted on. So thank you
Johan Rade for this contribution!

Best Regards,

--
Christian Pfligersdorffer
Software Engineering
http://www.eos.info
 
John Maddock wrote:
> The review of Johan Rade's floating point utilities starts today.
>
> [...]
>
> 3) C++ locale facets: these will read and write non-finite
> numbers in a portable and round-trippable way: that is not
> otherwise possible with current C++ std library
> implementations.  These are particularly useful for
> number-serialisation for example.
> 
> Since the design is already specified by the C++ standard for
> these facets, your review here should focus on
> implementation, testing, documentation, and perhaps where in
> Boost these should best be placed if accepted.
> 
> These look to be a useful collection of utilities, so I'll
> look forward to your reviews,