Gennaro Prota <[EMAIL PROTECTED]> writes:
> On Wed, 08 Jan 2003 12:08:40 -0500, David Abrahams
> <[EMAIL PROTECTED]> wrote:
>
>>I basically agree with everything you've said, especially about the
>>separate traits (metafunctions)! I was just pointing out some overlap
>>with existing libraries.
>
> Ok, here's what I propose:
>
> a) cleaning up the whole implementation of boost/detail/limits.hpp by
>
> - getting rid of all the stuff like:
>
> template<>
> class numeric_limits<bool>
> : public _Integer_limits<bool, false, true, 0>
> {};
>
> template<>
> class numeric_limits<char>
> : public _Integer_limits<char, CHAR_MIN, CHAR_MAX>
> {};
>
> template<>
> class numeric_limits<signed char>
> : public _Integer_limits<signed char, SCHAR_MIN,
> SCHAR_MAX>
> {};
>
> because, of course, max_of and min_of can be used for this.
> Example:
>
> static T min() throw() { return min_of<T>::value; }
>
> [Or, if you prefer... ;-)
>
> return implicit_cast<T> (min_of<T>::value);
>
> ]
Uh, wait a sec. Is it a good idea to mess with
boost/detail/limits.hpp? It's just a workaround for broken/missing
numeric_limits implementations, and it was a pain to get right. Did
you mention this before? If so, I guess I missed it.
> - in general, calculating values instead of providing them
> explicitly when this is feasible in a portable way.
>
> Example: for built-in integers, instead of having a hack like
>
> template <class _Int,
> _Int __imin,
> _Int __imax,
> int __idigits = -1>
> class _Integer_limits : public _Numeric_limits_base<_Int>
>
> that either "calculates" (wrongly) digits or takes the opposite
> of the value that the user passes (__idigits), we could have:
>
> BOOST_STATIC_CONSTANT(int, digits, precision<T>::value);
I guess if you think it's doing something wrong and you can fix it,
it's worth doing.
> Note, as to digits and digits10, that a similar clean up is
> possible for floating point types too, by adding e.g.:
>
>
> template <typename T> struct digits {
> BOOST_STATIC_CONSTANT(int, value = 0); // dummy value;
> (debatable)
> };
>
> template <> struct digits<float>
> { BOOST_STATIC_CONSTANT(int, value = FLT_MANT_DIG); };
> template <> struct digits<double>
> { BOOST_STATIC_CONSTANT(int, value = DBL_MANT_DIG); };
> template <> struct digits<long double>
> { BOOST_STATIC_CONSTANT(int, value = LDBL_MANT_DIG);};
Not sure if this will work portably.
> b) Modifying integer_traits.hpp to use max_of and min_of. This is
> just for backward compatibility because I think integer_traits
> should be simply deprecated (if the information one wants to provide
> is const_max and const_min for what reason should he add that
> information somewhere else, like numeric_limits<>? And what is the
> derivation good for?)
This was the part I thought I was agreeing with; I don't know.
> What do you think? If there aren't objections I could at least
> upload the needed code to the boost sandbox.
>
> Genny.
>
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>
--
David Abrahams
[EMAIL PROTECTED] * http://www.boost-consulting.com
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