On Mon, 20 Jun 2016 18:07:46 +0100 Tom Hacohen <t...@osg.samsung.com> said:
> On 19/06/16 02:27, Carsten Haitzler wrote: > > On Fri, 17 Jun 2016 09:41:39 +0100 Tom Hacohen <t...@osg.samsung.com> said: > > > >> On 17/06/16 03:28, Carsten Haitzler wrote: > >>> On Thu, 16 Jun 2016 19:13:20 +0100 Tom Hacohen <t...@osg.samsung.com> > >>> said: > >>> > >>>> On 03/06/16 20:17, Cedric BAIL wrote: > >>>> <snip> > >>>>>>> also promises should become eo objects with event cb's > >>>>>>> so they work just like everything else. i can ref, unref, delete and > >>>>>>> whatever them like everything else. > >>>>> > >>>>> As said above, this does work. Example with event : > >>>>> eo_promise = efl_file_set(image, "toto.jpg", NULL); > >>>>> eo_event_callback_array_add(eo_promise, promise_callbacks1(), NULL); > >>>>> eo_event_callback_array_add(eo_promise, promise_callbacks2(), NULL); > >>>>> > >>>>> In this 3 lines, there is already 2 case in which that fail. First if, > >>>>> the object is done before the callback is set, data are lost and there > >>>>> is no way to get any event. Ofcourse, we can override the behavior of > >>>>> events on this eo_promise completely. Now let's imagine, that we > >>>>> actually do always store the events, so that everytime someone > >>>>> register a callback we can send the event. Still you can't auto del > >>>>> the object at any point in time, you have to force the user to > >>>>> implement the eo_del and to always provide both a then and cancel > >>>>> callback. > >>>>> > >>>>> Other possibility, it is an event on the object itself. > >>>>> eo_event_callback_array_add(image, promise_callbacks1(), NULL); > >>>>> efl_file_set(image, "toto.jpg", NULL); > >>>>> eo_event_callback_array_add(image, promise_callbacks2(), NULL); > >>>>> > >>>>> Same again, this can not work. The first group of event handler, > >>>>> promise_callbacks1(), may actually be triggered by a previously > >>>>> running promise on the object, so you have to first forcefully stop > >>>>> the previous operation. This would add complexity. And still the > >>>>> second callback has the same issue as the previous case, if it is a > >>>>> normal eo event, it could have been triggered before any callback get > >>>>> registered and the event be lost... Same story short, doesn't work. > >>>>> > >>>> > >>>> I'm currently reading through the thread, and I didn't see anything > >>>> mentioned about this other than a casual remark you made, so just wanted > >>>> to make it crystal clear regarding implementing it as an Eo object. > >>>> The whole point/magic of inheritance is that you can and are supposed to > >>>> override functions if needed. Overriding callback add to call the > >>>> callback immediately upon addition (if already done) is how I would > >>>> implement promise callbacks. It's clean, easy and as intended. This is > >>>> definitely not a problem. > >>> > >>> just for convenience i think having a special eo_promise_then(obj, cb1, > >>> cb2, data); may be best as its the simplest and is not pretending to ADD > >>> a cb in the name. it sets it explicitly. this needs special treatment > >>> like the eo event callbacks of course. > >>> > >>> but using an eo event is possible by override indeed, but here is the > >>> issue. you have to wait until either "then" or "else" or both are set. > >>> since you set one then set another... you will have to always add one of > >>> them as a NULL or dummy cb just to do this. having a single method/func > >>> set both makes more sense. in fact this likely needs manual > >>> binding/.handling per language anyway. i'm really only thinking of eo > >>> events for EXTRA features like progress events on a promise that happen > >>> before the success/fail cb's above. > >>> > >>> > >> > >> This is explained better in my reply to the initial post of this thread, > >> but essentially you don't. What you are missing, and why life-cycle can > >> be pretty broken, and why this doesn't matter is that you can register a > >> few "then" and a few "cancel" in promises. That is actually the power of > >> promises, that you can chain them and use them for a few things. This is > >> dealt with nicely. See the post I mentioned. > > > > register a few then/else cb's on the same promise? at least that should not > > be possible (it should not work). on;y one else/then cb (zero or one of > > each). > > > > > > Why not? Anyhow, as I said, that is very common in js land and how race > and all are probably implemented. eh? well eina_promise allowed only a single then... which i think is the sanest way here. limit it to one. the reason is that otherwise you never know when the promise is finished its setup. you need a special done() call on the promise then to tell it you're done attaching callbacks. e.g. for the case it's an async load but the load finds the target in an in-memory cache already and wants to immediately call the then func - when does it call it? if you can add any number of then funcs... ? -- ------------- Codito, ergo sum - "I code, therefore I am" -------------- The Rasterman (Carsten Haitzler) ras...@rasterman.com ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. 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