Re: [boost] New Boost.XInt Library, request preliminary review

Subject: Re: [boost] New Boost.XInt Library, request preliminary review
From: Jeffrey Lee Hellrung, Jr. (jhellrung_at_[hidden])
Date: 2010-04-08 14:18:46

Chad Nelson wrote:
> On 04/07/2010 05:04 PM, Joachim Faulhaber wrote:
[...]
>> I think, the values of a numeric types should be
>> (1) closed under their fundamental operations e.g. +.
[...]
> 
> I'm not sure what your first point means, but I think I agree, for the
> most part.

Closed in the sense that if x, y in S, then (x op y) in S as well.

[...]
>> and provide a NaN and Infinity closure as template
>>
>> template<class IntegralT, class ClosureTraits=...> closed { ... }
>>
>> because the way in which NaNs, Infinities (and maybe more special
>> values) are handled should be the same for all the different
>> implementations of integral numeric types.
> 
> I'm not sure what you mean by "a NaN and Infinity closure". I understand
> templates, and I think I understand closures (at least as provided by
> languages like Lisp), but I can't make out what you're trying to say
> there. Is that a C++0x (or C++1x, now) thing?

Closure in the (general) mathematical sense, not in the programming 
language sense.  I.e., extend your set to make previously-undefined 
operations defined (and somehow consistent with the existing properties 
of interest).

- Jeff