Reading your explanation and rereading the change notes at http://wiki.ecmascript.org/doku.php?id=harmony:observe (need to learn to look there more) I see how this change came to be.
Time for a minor hack to get it in and then some major rewriting to support it properly along with other changes like the Synthetic Change Records. Thanks for the clearup, - Jeremy On Wed, Sep 10, 2014 at 9:25 AM, Erik Arvidsson <[email protected]> wrote: > I think you are confusing the internal spec function from the API function > deliverChangeRecords. > > Object.deliverChangeRecords always returns undefined. It is the internal > [[DeliverChangeRecords]] that gets called until the queue of change records > is exhausted. > > The point of Object.deliverChangeRecords is to get a synchronous delivery > to the function that is listening to the mutations. > > http://jsbin.com/qazipicipume/1/edit?js,console > > HTH > > > On Tue, Sep 9, 2014 at 9:50 PM, Jeremy Darling <[email protected]> > wrote: > >> I maintain a Shim of Object.observe ( >> https://github.com/jdarling/Object.observe) that has been gaining in >> popularity since Chrome implemented the functionality in their public >> release. It had some usage before but it has really started picking up >> since. >> >> That being beside the point, someone asked us about implementing the >> update to deliverChangeRecords ( >> https://github.com/jdarling/Object.observe/issues/13). It seems that at >> some time deliverChangeRecords moved from the ObjectNotifier to Object >> itself. >> >> Per the spec at >> http://wiki.ecmascript.org/doku.php?id=harmony:observe_public_api >> >> Object.deliverChangeRecords >> >> A new function Object.deliverChangeRecords(callback) is added, which >> behaves as follows: >> >> 1. If IsCallable(*callback*) is not *true*, throw a TypeError >> exception. >> 2. Call [[DeliverChangeRecords]] with arguments: *callback* repeatedly >> until it returns false (no records were pending for delivery and callback >> no invoked). >> 3. Return. >> >> >> This seems very grey and not well defined at all. One would assume that >> per the above the following code would function calling changeHandler2 for >> all change records (and maybe, its unclear from the above, changeHandler1 >> as well). >> >> >> var obj = {}; >> var changeHandler1 = function(changes) { >> console.log('1)', changes); >> }; >> >> var changeHandler2 = function(changes) { >> console.log('2)', changes); >> }; >> >> Object.observe(obj, changeHandler); >> obj.test = 5; >> >> while(Object.deliverChangeRecords(changeHandler2)){ >> console.log('got a change') >> } >> >> So we went to Chrome 36 and looked at how it handled the above code. To >> our surprise changeHandler1 got called with the change but changeHandler2 >> did not get called, also 'got a change' was never logged to the console. >> >> This lead us to assume that the handler must be one that was already >> registered with Object.observe. So we tried the following code instead: >> >> var obj = {}; >> var changeHandler = function(changes) { >> console.log('1)', changes); >> }; >> >> Object.observe(obj, changeHandler); >> obj.test = 5; >> >> while(Object.deliverChangeRecords(changeHandler)){ >> console.log('got a change') >> } >> >> When running the above changeHandler seems to be called via the normal >> Object.observe pipe and still 'got a change' is not recorded in the >> console. Basically making Object.deliverChangeRecords appear to be a noop >> that actually ignores the callback that has been passed into it. >> >> So, after all the above, here is my question; What exactly is >> Object.deliverChangeRecords supposed to do? As a follow on to that, can >> someone post a test scenario that actually covers its proposed actions so >> we can implement it? >> >> Seems to me, to add it in the way Chrome as so far we could just noop it >> and go on, but that just doesn't feel right in the grand scheme of things. >> >> Thanks, >> - Jeremy >> >> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> > > > -- > erik >
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