[webkit-dev] ExecState::thisObject()

Adam Barth abarth at webkit.org
Fri Jul 10 18:11:26 PDT 2009

Sent again from the right address.  Gmail hates me today.

On Fri, Jul 10, 2009 at 6:10 PM, Adam Barth<abarth at eecs.berkeley.edu> wrote:
> On Fri, Jul 10, 2009 at 6:04 PM, Maciej Stachowiak<mjs at apple.com> wrote:
>> On Jul 10, 2009, at 5:55 PM, Adam Barth wrote:
>>> Eric and I spent some more time this afternoon looking at this.  We
>>> don't think the ExecState::thisValue() approach is going to work.  We
>>> implemented hacky version to experiment with, but the problem is with
>>> cases like this:
>>> document.body
>>> In evaluating this case, the "this" value isn't what we want because
>>> our computed "thisValue" is for the running function, not for the
>>> getter.
>> Is it definitely right for document.body to make a wrapper using prototypes
>> from the document's host window, rather than from the accessing function's
>> window? What do other browsers do?
> That's correct.  Other browser's get this case right.  Here are a
> couple test cases you might find interesting:
> http://webblaze.org/abarth/tests/protoconfused/test1.html
> http://webblaze.org/abarth/tests/protoconfused/test2.html
> The question is how to compute the correct wrapper context in all
> cases.  There are a bunch of approaches that cover 80% of the cases.
> The trick is finding an approach that works for 100% of the causes.
> Adam

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