On Sep 24, 2009, at 9:47 AM, Brendan Eich wrote:
On Sep 24, 2009, at 7:55 AM, Maciej Stachowiak wrote:
It seems like this is a Web IDL issue. I don't see any reason for
Web IDL to move to ECMA. It is a nominally language-independent
formalism that's being picked up by many W3C specs, and which
happens to have ECMAScript as one of the target languages. Much of
it is defined by Web compatibility constraints which would be
outside the core expertise of TC39.
Some of us on TC39 have lots of Web compatibility experience :-P.
Probably the best thing to do is to provide detailed technical
review of Web IDL via the W3C process.
Expertise on both sides of the artificial standards body divide may
very well be needed. The rest of this message convinces me it is
needed.
One problem with inviting review via the W3C process is getting
attention and following too many firehose-like mailing lists. es-discuss@mozilla.org
is at most a garden hose, which is an advantage.
Another problem is that not all Ecma TC39 members are W3C members
(their employers are not members, that is).
The converse of all these problems would arise if the spec became an
ECMA spec. Indeed, possibly worse, because ECMA has no formally
defined process for external review of a specification (though ECMA
subgroups could define their own process presumably).
There are transparency problems on both sides, IMHO. People in dark-
glass houses...
https://mail.mozilla.org/pipermail/es5-discuss/2009-September/003312.html
and the rest of that thread
https://mail.mozilla.org/pipermail/es5-discuss/2009-September/003343.html
(not the transactional behavior, which is out -- just the
interaction with Array's custom [[Put]]).
https://mail.mozilla.org/pipermail/es-discuss/2009-May/009300.html
on an "ArrayLike interface" with references to DOM docs at the
bottom
https://mail.mozilla.org/pipermail/es5-discuss/2009-June/002865.html
about a WebIDL float terminal value issue.
It seems like these are largely Web IDL issues (to the extent I can
identify issues in the threads at all).
TC39 members, Mark Miller articulated this yesterday, hope to
restrict host objects in future versions of the JavaScript standard
from doing any nutty thing they like, possibly by collaborating with
WebIDL standardizers so that instead of "anything goes" for host
objects, we have "only what WebIDL can express".
Catch-all magic where host object interfaces handle arbitrary
property gets and puts are currently not implementable in ES -- this
may be possible in a future edition, but even then it will carry
performance penalties and introduce analysis hazards. We hope to
steer ES bindings for WebIDL-expressed interfaces away from catch-
all patterns.
We could recommend avoiding catch-alls as a best practice. However,
many legacy DOM interfaces require catch-all behavior, so it can't be
completely eliminated. If we want to restrict host objects to what
WebIDL allows, but not break the Web, then catch-all getters and
putters have to be among the things it allows.
Beyond this tarpit, we're interested in the best way to linearize
multiply-inherited WebIDL interfaces onto prototype chains, or
whether to use prototype chains at all -- or in the seemingly
unlikely event ES grows first-class method-suite mixins, binding
WebIDL inheritance to those. We would welcome use-cases and
collobaration, at least I would. Who knows what better system might
result?
Yes, linearization of multiply-inherited interfaces (and multiple
interfaces that are present but not inherited) is something that could
use careful review and a better design. When I said "these are largely
Web IDL issues" I mean "not directly issues for the HTML Working
Group". I did not mean to imply that TC 39 shouldn't have input - it
should.
There are larger (and less precise concerns at this time) about
execution scope (e.g., presumptions of locking behavior,
particularly by HTML5 features such as local storage). The two
groups need to work together to convert these concerns into
actionable suggestions for improvement.
There was extensive recent email discussion of local storage
locking on the <wha...@whatwg.org> mailing list. We could continue
here if it would be helpful. I'm not sure it's useful to discuss in
person without being up to speed on the email discussion. Here are
some relevant threads: <http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-September/022542.html
> <http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-September/022672.html
> <http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-September/022993.html
> <http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-September/022810.html
>.
Thanks for the links, I was aware of these but hadn't read them.
Mandatory try-locks in JS, just say no.
I didn't like most of the proposed designs either.
I'm not sure what the other concerns about "execution scope" are -
seems hard to discuss fruitfully without more detail.
The term I used was "execution model". "scope" is a mis-transcription.
Are there specific issues other than the concurrency model for storage
APIs?
We should take steps to address the following "willful violation":
If the script's global object is a Window object, then in
JavaScript,
the this keyword in the global scope must return the Window object's
WindowProxy object.
This is a willful violation of the JavaScript specification
current at
the time of writing (ECMAScript edition 3). The JavaScript
specification requires that the this keyword in the global scope
return the global object, but this is not compatible with the
security
design prevalent in implementations as specified herein. [ECMA262]
Wasn't ES5 fixed to address this?
No, nothing was changed in ES5 and it is not clear without more
discussion with various experts active in whatwg, w3, and Ecma what
to do.
Since you asked, I think you make the case that we should
collaborate a bit more closely.
Sounds like a good issue to discuss then.
I know the feedback was passed along.
Yes, but describing the problem does not give the solution.
If ES5 has requirements on this that match ES3, then it has a
requirement that Firefox, Safari and Chrome (and I think Opera?) are
all violating, and likely will continue to violate for the foreseeable
future. That seems like a problem. (Unless we convince ourselves that
the split global object pattern somehow doesn't actually violate the
ECMAScript spec.)
Regards,
Maciej
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