Thoughts on IEEE P754

Mike Cowlishaw MFC at uk.ibm.com
Fri Aug 22 12:15:17 PDT 2008


> Mike Cowlishaw wrote:
> > Seems to me the problem here is not decimal (or binary) 
representations 
> > but arrays (consider a(0.0) and a("0.0")).
> > 
> > In effect the array definition in ES3 says -- in a rather roundabout 
way 
> > -- that all indexes must be an integer (which fits in 32 bits if 
encoded 
> > in binary).  So, as long as there's a toInt32 in there, decimals with 
> > trailing zeros after the point are just fine.  In other words the 
> > processing of array indexes could (conceptually) be 
> > toString->toNumber->toInt32 (or something like that).
> 
> That's incompatible with ES3.  There is no toInt in there.

I confess it's eight years since I looked at that text, but I wasn't 
saying there was a toInt32 in ES3.  I'm just saying that that could/should 
be added.  Surely there was something about array indexes having to have 
the same result as though it had a toInt32?  Anything else that wouldn't 
convert to an integer would be 'out of range'?

ES arrays are essentially just like Java arrays -- indexed by integers, 
zero through length-1?

Mike





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