On Wed, Nov 12, 2014 at 4:18 PM, James Long <[email protected]> wrote: > On Wed, Nov 12, 2014 at 7:14 PM, Tab Atkins Jr. <[email protected]> wrote: >> On Wed, Nov 12, 2014 at 4:07 PM, James Long <[email protected]> wrote: >>> Maybe this would be resolved if you could answer this: how do you mark >>> an async function to be a top-level one? I don't see anywhere that >>> says "I don't return a promise, I want errors inside of me to >>> literally throw. I am an all-powerful top-level consumer of async >>> stuff"). Seems like that would need extra syntax? >> >> There is currently no way to do so. If there was, they still wouldn't >> "literally throw", because again, that's impossible - by the time the >> promise rejects, it may be another turn entirely, and the program >> counter is long past the callsite. The best it can do is be an >> automatically-unhandled error, caught by window.onerror. > > You do realize that generators have a `throw` method, and way long > after the generator is yielded you can throw and error from the yield > point and current devtools will correctly pause at that point if you > enable "pause on uncaught exceptions"? A top-level async function > would throw in exactly this same way when an a promise that `await` it > waiting for fails.
Yes, that's exactly what I mean by "automatically-unhandled error". It's impossible to catch an asynchronous error from the synchronous code that called it, but you can appeal to a global environment to catch it. > This really seems like a huge oversight that there isn't a way to mark > an async function as top-level. When async/await gets here people are > going to want to use that *everywhere*, as they should, and forcing > them to only interact with them as middle-men just so that you can > call `.done()` on an old-style promise chain is weird. Marking a function as "top-level" is just syntax sugar for calling .done() on the returned promise. (Assuming that .done() can forward rejections to window.onerror.) It might be useful, I dunno, but it doesn't offer anything fundamentally new. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
