Scoped binding of a method to an object

Brendan Eich brendan at mozilla.com
Sun Oct 13 10:49:28 PDT 2013


> Erik Arvidsson <mailto:erik.arvidsson at gmail.com>
> October 13, 2013 10:32 AM
> We did proposes this back in 2011
>
> http://wiki.ecmascript.org/doku.php?id=strawman:scoped_object_extensions
>
> I wasn't at this actual F2F meeting so I don't know many details.
> Brendan might remember what the blocking issue was?

I wrote why in my reply, cited below:

> Your subject recalls a defunct proposal to add lexically-scoped but 
> heap-based -- therefore object property-lookup performance hindering 
> -- extension properties. This proposal died precise because of the 
> performance problem.

Every property access sprouts a third parameter beyond object and 
property name, namely a lexical scope token of some kind. All property 
maps in objects shared in the heap also sprout such a scope token along 
with property name.

(This is quite reminiscent of ES4 namespaces, which we agreed to reject 
from any future ECMA-262 in order to forge Harmony in 2008. See 
https://mail.mozilla.org/pipermail/es-discuss/2008-August/006837.html.)

Implementors objected, including V8 folks (if I recall correctly, 
Andreas Rossberg). This was at the May 2011 TC39 meeting hosted at the 
University of California at Santa Cruz.

/be


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