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Re: [Public WebGL] typed arrays + edge cases



On Feb 3, 2010, at 2:50 PM, Vladimir Vukicevic wrote:

> 
> A few edge cases keep coming up that are underspecified currently... a few of these we talked about in the past, but I don't know if we captured
> 
> - If a non-numeric array property is set/read, what happens?
> 
> Suggestion: exception (we have out-of-bounds numeric indexes spec'd to raise an exception currently, so this falls in the same category to me)

I'd really like this to work. It enables using arrays to store additional, application specific data, just like normal Arrays.

> 
> - If the array type is non-float and a non-numeric value is stored, what happens?
> 
> Suggestion: 0 or exception
> 
> - If the array type is float and a non-numeric value is stored, what happens?
> 
> Suggestion: NaN or 0 or exception

What happens if you do this on an Array? We should match that behavior.

> 
> - If the array type is float and someone bit-fiddles an unusual NaN in there, does that unusual NaN get passed to the engine to deal with (even if it might not normally use them, e.g. signalling NaN etc.)?
> 
> Suggestion: I don't have a good one.  The engine should maybe convert all NaNs into whatever NaN it understands on element access?

I think all invalid NaN variants should be converted to a quiet NaN, which is what JS supports, right? I think the values we should support are all valid, normalized floats, +/-Inf and a quiet NaN. Everything should be converted to a quiet NaN.

-----
~Chris
cmarrin@apple.com




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