On 2/3/14 1:15 PM, Domenic Denicola wrote:
From: Boris Zbarsky <[email protected]>
I'm saying that the algorithm in the [[Call]] of those objects (or rather of the
functions being bound in this case) explicitly references a part of the environment
called the "script settings object stack" and expects whoever plans to invoke
that [[Call]] to maintain it as needed.
This expectation seems untenable.
It's completely tenable in today's world where all JS is run to
completion any anything async is happening via the browser event loop
and WebIDL; those maintain the stack in question across async
invocations, and the behavior of the stack across synchronous calls is
defined in the whatwg specification. To the extent that the latter is
true, you could argue that it did fork [[Call]] on scripted functions in
ES, I guess...
As we add an event loop to ES, we will need to maintain that stack in
ES, presumably, or some equivalent. But right now we don't.
It should be the job of a function that depends on global state to specify how
that dependency on global state works.
It's defined. The global state just needs to be there.
What I am understanding from this is that DOM specs have forked the ES spec's definition
of [[Call]] to include a hidden "script settings object stack" parameter, which
ES is not aware of.
You can view it that way if you want, I suppose. Or you can view
implementations as having implicit things like that already, for
postMessage and the like.
But again, you're ratholing on this particular example. My point was
that there are lots of edge cases like this in the web platform that we
shouldn't force every single spec author to think about. Some of them
are due to DOM things, some are due to ES things. To the extent
possible, we should make it possible to write correct and readable
specifications that do the right thing in these edge cases even if the
specification author wasn't aware of the complications.
-Boris
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