Le 22/04/2013 19:32, Dean Landolt a écrit :
I was just saying there will be pressure to include support for
thenables (already in DOMFutures). If you believe otherwise don't let
me dissuade you -- I would absolutely love it if I were proven wrong!
I guess it would take making sure no content can be confused by the
current steps 3-5 of the current resolve spec [1]. I believe browser
vendors have tools to study this kind of things.
CasperJS [2] create objects with a then method [3]. Interestingly, this
doesn't run in the browser (until someone decides to re-implement it of
top of a web browser or FirefoxOS. [4] ?). Potentially more
interestingly, Casper objects could be promises subclasses (to be
considered).
It wouldn't be surprising if there were content on the web where the
promise subclass trick couldn't work.
In any case, considering that an object with a 'then' function is a
promise is a recipe for confusion. Promise/A+ folks asked for and are
happy about it. The rest of the webdevs who aren't aware of this subtle
non-intuitive rule will have a very hard time when, for whatever reason,
they have a 'then' function in a resolve value and their code really
behaves in a way they don't understand.
I don't think in the entire platform there is a precedent of doing this
(maybe for a good reason?). We'll see what web browsers end up implementing.
David
[1] http://dom.spec.whatwg.org/#concept-resolver-resolve
[2] http://casperjs.org
[3] http://casperjs.org/api.html#casper.then
[4] https://github.com/laurentj/slimerjs
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