[boost] [metamath] Using mpl::numeric_cast

From: Cromwell Enage (sponage_at_[hidden])
Date: 2005-09-20 15:24:35

Scattered throughout the metamath library are template
specializations of numeric metafunction classes like
the following:

template <>
struct times_impl<
    integral_c_tag
  , metamath::double_c_tag
>
{
    ...
}

The purpose of mpl::numeric_cast<> (or
BOOST_MPL_AUX_NUMERIC_CAST) is to render such
specializations unnecessary.  I understand that if
template instantiation overhead is a problem then the
current situation is okay, but if we start
implementing more numeric metatypes such as
metamath::float_ and/or metamath::long_double_, then
the net increase in code size will become an issue.

Also included in the last update of my math sublibrary
are files from the metamath library that I modified to
make use of BOOST_MPL_AUX_NUMERIC_CAST:
*  In <boost/metamath/double/double.hpp> I modified
double_c_tag so that it inherits from
boost::mpl::int_<8> (an arbitrary constant higher than
zero).
*  In <boost/metamath/double/integral_to_double.hpp> I
added a template specialization of
BOOST_MPL_AUX_NUMERIC_CAST that uses
integral_to_double<>.
*  In the other files I deleted the redundant
specializations.

Let me know what you think.

                              Cromwell D. Enage

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