Nailing object property order

Brendan Eich brendan at mozilla.org
Thu Apr 16 18:37:57 UTC 2015


Also, it's too late. Engines are converging, inter-operation pressure 
points in one direction only: greater convergence and standardization.

It's true engines are not converging on the ancient insertion order, and 
that caused some interop stress, but we are over that hump now. See 
https://code.google.com/p/v8/issues/detail?id=164&can=1&q=enumeration&colspec=ID%20Type%20Status%20Priority%20Owner%20Summary%20HW%20OS%20Area%20Stars 
(a long, and long-resolved, V8 issue).

Bergi's frustration is understandable. Leaving things unspecified for 
too long was a failure on our part in tending the spec, or a trade-off 
(we had other things to do ;-). All water under the bridge, but we're 
not stepping back to unspecified behavior. Because engines aren't, 
because developers do not want.

And agree with Mark: POITROAE.

/be

Mark S. Miller wrote:
> Developer productivity > hypothetical minor performance gains.
>
> +1 to all steps to make the specified behavior more deterministic, 
> including this one.
>
>
> On Thu, Apr 16, 2015 at 10:07 AM, liorean <liorean at gmail.com 
> <mailto:liorean at gmail.com>> wrote:
>
>     I'm very much opposed to locking this down for general objects because
>     it locks the implementation choices for generic objects down. What if
>     the engine backing implementation was, say, some variation of a trie
>     for instance? It cannot really be done today without adding extraneous
>     data into the structure, because lookup in that case happens on a
>     character by character basis, not on a whole string basis, so
>     properties that use common prefixes would always end up adjacent and
>     even if the keys weren't inserted in order by bit patterns into the
>     trie as most implementations do, they would still be grouped by common
>     prefix.
>     --
>     David "liorean" Andersson
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>
> -- 
>     Cheers,
>     --MarkM
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