[+google-caja-discuss] Hi John,
First, thanks for commenting on repairES5.js. Please keep the comments coming. Anything not appropriate for the es-discuss like should instead be posted to google-caja-discuss, cc'ed. But please look instead at < http://code.google.com/p/es-lab/source/browse/trunk/src/ses/repairES5.js>, which is the version in review at <http://codereview.appspot.com/5489103/>. Regarding this issue, thanks for raising it here. I was planning to do so myself, once I flesh out < http://wiki.ecmascript.org/doku.php?id=strawman:fixing_override_mistake>. But what's already there is coherent enough to look at. The Irony of this "feature" of the language is that SES pays a significant performance penalty only on platforms that pass the test you link to. On platforms that fail this test, our "repair" in review at < http://code.google.com/p/es-lab/source/browse/trunk/src/ses/repairES5.js#2252> makes them much faster. On Thu, Dec 29, 2011 at 2:56 PM, John-David Dalton < [email protected]> wrote: > So I was digging through repairES5.js > > http://code.google.com/p/google-caja/source/browse/trunk/src/com/google/caja/ses/repairES5.js#1427 > > and noticed that: > > var a = Object.freeze({ 'x': 1 }); > var b = Object.create(a); > b.x = 2; > b.x; // should still be 1 > > Then I dug into spec and noticed: > http://es5.github.com/#x8.12.4 > > so `b.x` remains 1 because the property 'x' of its [[Prototype]] is > writable: false. > > Ok, so why all of that when you could simply do: > > var b = Object.create(a, { > 'x': { > 'configurable': true, > 'enumerable': true, > 'writable': true, > 'value': 2 > } > }); > > or > > Object.defineProperty(b, 'x', { > 'configurable': true, > 'enumerable': true, > 'writable': true, > 'value': 2 > }); > > b.x; // 2 > > - JDD > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > -- Cheers, --MarkM
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