Thoughts on IEEE P754

David Jones drj at ravenbrook.com
Fri Aug 22 14:26:26 PDT 2008


On 22 Aug 2008, at 20:42, David-Sarah Hopwood wrote:

> David Jones wrote:
>> On 22 Aug 2008, at 19:28, David-Sarah Hopwood wrote:
>>> Two values that are === should index the same property [*].
>>
>>> [*] but not conversely: two values that index the same property are
>>>      not necessarily ===.
>>
>> That highly desirable, but not true, as my earlier message  
>> illustrates.
>> In ES3 the ToString operator on Numbers is not required to be a true
>> function in the sense of always yielding the same result for the same
>> input.
>
> That's true, but I strongly believe that it is a specification bug  
> that
> should be fixed for ES3.1 and ES-Harmony.

Well, so do I.  But until 3 implementations get on board and say "we  
can live with changing the note at the end of section 9.8.1 to being  
normative" then it looks like it's Not Gonna Happen.

>
> In practice, AFAIK, all the common JavaScript implementations do  
> have a
> deterministic ToString operation on numbers (that is, deterministic  
> for
> each implementation; I don't know whether there are differences  
> between
> implementations).
>
> <https://mail.mozilla.org/pipermail/es-discuss/2008-July/006627.html>
> # In order to ensure implementations all behave the same way I suggest
> # the note at end of section 9.8.1 be moved to normative status.
>
> I agree.

drj


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