ES Decimal status

Brendan Eich brendan at mozilla.org
Wed Sep 24 09:17:40 PDT 2008


On Sep 24, 2008, at 9:01 AM, Mike Cowlishaw wrote:

>> I'm not sure what you are getting at. a[1] and a[1.000] refer to the
>> same property in ECMAScript, but a[1m] and a[1.000m] would not. Are
>> you saying this isn't a problem?
>
> Absolutely not a problem ... many languages (and ES itself) which  
> index
> 'arrays' by strings treat the index "1.000" as different from "1", and
> this is not considered a problem.

But they do not treat 1.000 as an index differently from 1. Explicit  
string indexes, whether literally expressed or computed, are not the  
issue here.


> This is, no doubt, because if one is treating array indexes as a  
> set of
> integers you use integer operations on those indexes (almost  
> exclusively
> +, -, and *).  If one does use a divide,

Maciej pointed out reciprocal multiplication as strength-reduced  
division; this is done often enough in graphics and other low-level  
code.


> it would be carefully chosen to
> produce an integer result;

But what if scale is preserved?


> anything which produced a result without an
> exponent of 0 would always be more likely to give a non-zero  
> fraction that
> .0, .00, .000, etc. -- and those non-zero ones would fail rapidly.

Sorry, I didn't follow this ("that" should be "than"?).

/be

>



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