[boost] Re: Extend numeric_limits<> integer traits?

From: Beman Dawes (beman_at_[hidden])
Date: 1999-08-06 12:59:26

At 05:59 PM 8/6/99 +0200, Valentin Bonnard wrote:

>Beman Dawes wrote:
>
>> For many uses, these are sufficient.  But min() and max() are
>> problems because they are not constant expressions (5.19) and some
>> uses require constant expressions.
>
>Like C array declarations, cases in switch 
>and integral template parameters
>
>> Valentin worked around this by providing an
extended_numeric_limits<>
>> class derived from numeric_limits<>, which for integers added:
>> 
>>    static const T max_constant;
>>    static const T min_constant;
>> 
>> (I have changed lots of details from Valentin's header for the
sake
>> of exposition.)
>> 
>> Now the 64-bit question:
>
>I would go as a far as 128 bits.
>
>>    Is it worthwhile for boost to supply an
extended_numeric_limits<>
>> class?
>> 
>> To me, it seems more trouble that it is worth.  What do others
think?
>
>Simply indispensable for my integral types library.

What is the usage?  Does it really require a constant expression, or
would std::numeric_limits<T>::max() or std::numeric_limits<T>::min()
do?

>Trivial to define in term of <climits>.

Nothing is trivial that involves a new header, educating users, etc.
The implementation is certainly trivial if you don't mind using the
<climits> macros.

It seems to me that this is really a hole in the C++ standard's
numeric_limits<>.  Was there ever discussion of providing constant
expression forms of max and min for integers?  Can anyone remember
the rationale for not doing so?

--Beman