domains have a parallel to sync code. Use event emitters for your sync
flow. promises only have a parallel to sync code if you use promises for
sync & async code.
On Tue, Oct 2, 2012 at 7:28 PM, Domenic Denicola <
dome...@domenicdenicola.com> wrote:
> I forgot to add, this is especially important in Node, where promises
> solve the entire uncaught-exception-in-callbacks problem if used
> consistently throughout an app. An exception in a very deeply-nested
> promise callback simply transforms that innermost promise into a rejected
> promise, which then propagates up the chain to the closest rejection
> handler (just like sync exceptions!). This is unlike the situation with
> callbacks, where an exception in a deeply-nested callback jumps immediately
> out to process.on("uncaughtException").
>
> Notably this uncaught exception jumping is the problem domains attempt to
> solve; they do so in the majority of cases, when all your asynchronicity
> eventually comes from the EventEmitters that domains hook into, at the cost
> of introducing an abstraction that---unlike promises---has no parallel to
> sync code.
>
> But yeah, since jQuery doesn't translate exceptions into rejections, this
> entire benefit is lost and you're back in traditional callback land, where
> an exception inside a callback jumps all the way back up to window.onerror.
>
>
>
> On Tuesday, October 2, 2012 10:18:42 PM UTC-4, Domenic Denicola wrote:
>>
>> jQuery promises also aren't interoperable with other promise-consuming
>> libraries, because they do not transform errors thrown in callbacks into
>> rejection reasons, violating Promises/A. So e.g.
>>
>> function doOperationAndDontGiveUp(**operation) {
>> return operation().then(null, function (error) {
>> if (error instanceof TemporaryNetworkError) {
>> return doOperationAndDontGiveUp(**operation);
>> }
>> throw error;
>> });
>> }
>>
>> doOperationAndDontGiveUp(**whatever).then(console.log, function (error) {
>> console.log("A non-temporary error: ", error);
>> });
>>
>> will not work, because you can't re-throw errors in jQuery to stay in a
>> rejected state; the error will end up uncaught by any handlers except
>> window.onerror/process.on("**uncaughtException"), and so the rejection
>> handler will never be called.
>>
>> There's also the issue where jQuery promises can be resolved with
>> multiple values, which other libraries cannot consume.
>>
>> You're better off using a different promise library, like Kris Kowal and
>> myself's Q, or Mariusz's deferred, or When, in both the browser and the
>> server, and immediately converting any jQuery promises to real Promises/A
>> promises using e.g. Q.when(jQueryPromise).
>>
>>
>> On Tuesday, October 2, 2012 12:01:03 PM UTC-4, Jeff Barczewski wrote:
>>>
>>> Mariusz,
>>>
>>> I was using an old version of your deferred module, Deferred@0.1.1which was
>>> API compatible with jQuery.
>>>
>>> I guess for upgrading many things have changed since then:
>>>
>>> - .promise() becomes .promise
>>> - Deferred.when() - I will have to create my own, right?
>>>
>>> Anything else that you remember which will need to change? (I know this
>>> was a long time ago when you changed it so not a big deal if you don't
>>> remember)
>>>
>>>
>>> If I want to keep the jQuery.Deferred style API (for consistency on all
>>> client and server code) but use your latest module, then I guess I need to
>>> create some light adapters which will use your api under the covers.
>>>
>>> If you have any other ideas or thoughts on this let me know.
>>>
>>> Thanks in advance!
>>>
>>> Jeff
>>>
>>>
>>> --
> Job Board: http://jobs.nodejs.org/
> Posting guidelines:
> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
> You received this message because you are subscribed to the Google
> Groups "nodejs" group.
> To post to this group, send email to nodejs@googlegroups.com
> To unsubscribe from this group, send email to
> nodejs+unsubscr...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/nodejs?hl=en?hl=en
>
--
Job Board: http://jobs.nodejs.org/
Posting guidelines:
https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
You received this message because you are subscribed to the Google
Groups "nodejs" group.
To post to this group, send email to nodejs@googlegroups.com
To unsubscribe from this group, send email to
nodejs+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/nodejs?hl=en?hl=en
