Re: [boost] [serialization] facets for non-finite numbers

From: Robert Ramey (ramey_at_[hidden])
Date: 2006-08-02 11:33:49

Johan Råde wrote:
> Paul A Bristow wrote:
>> Johan Råde wrote:
>>>  Paul A. Bristow wrote:> |
>>>  > Surely C99 signbit tests the sign bit?
>
>>>  You are right, but our goals are different. You are working on a
>>>  proposal to the C++ standardization committee. I writing code that
>>>  should work with existing C++ compilers and std lib
>>>  implementations. So I can not assume that the C99 signbit macro is
>>> present.
>>
>> OK, so why not write - or get someone else to write ;-)
>> a C++ is_negative function,
>> and use the signbit macro if available,
>> or make up your own bit test if not?
>>
>> There are a few variations with type, endianness and compiler, of
>> course, but not TOO many?
>
> I'm not going to do it.
> I don't need the sign bit in Nan (and 0),
> and I don't want to dig into the binary representation
> of floating point numbers on different platforms.
>
> If anyone needs it, let him write it.

> If he does,

and he writes corresponding tests, jamfiles, documentation
and includes support for the variety of compilers and libraries
that boost supports.

>I will add it to my code.

A very good answer.  The problem at hand is to define
otherwise undefined behavior that currently, can result in non-sensical
programs.  Your solution addresses that problem.  If someone
wants to address some other problem, facets can be written
for that and included in the "facets library".  People regularly
have problems with the current situtation.  When someone
proposes a solution, a bunch of other people chime in with
their proposal to expand the problem to the point of
insolubility.  The task is then too large to address and the
situation goes back to where it was before.  This is a boost
problem.

>
> --Johan Råde
>
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