On Mon, Apr 15, 2013 at 5:34 PM, Jake Verbaten <rayn...@gmail.com> wrote: > So one thing that is confusing is that `next()` has an API that looks like > the stream is a "pull stream". A "pull stream" means that you call next() > and it will give you the next value when it has it. This type of stream > generally buffers values internally and only gives you them when you pull > them out by calling next(). Node's streams2 API has a similar thing with a > read() API. > > The semantics of the stream are actually push, which means the stream will > just push values out whenever it has them and it's the consumers > responsibility to add listeners using `listen()`. The usage of `next()` is > confusing as it's easy to mistake the stream for being pull based.
Ah, I see the problem. Yes, under my proposal's semantics, you shouldn't be using `next` as the standard way to consume data - that's what `listen` is for. `next` is for when you just need the next update only (or the next update that satisfies some filter) - it imposes no constraints on the stream, so it's possible to miss updates even if you call `next` again inside the future's accept callback. For an example of where this is useful, check out my Font Futures proposal at <http://www.xanthir.com/b4PV1>. The `FontList#ready` function is *basically* equivalent to getting an observer stream off of the loadStatus attribute, and then calling `next("loaded")` on it. All you care about is the *very next* time it's "loaded" - if it flips between "loading" and "loaded" more, you don't really care. (Actually, to handle this properly you need a Stream subclass that remembers the stream's last update, and a `value` method that's identical to `next` except it first checks against the last update.) My proposal isn't meant to be a lossless stream, though like I said, it's not hard to imagine a subclass that represents one, and a method that generates a lossless stream out of a lossy stream via buffering. ~TJ _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
