On Fri, Aug 17, 2012 at 6:49 PM, Brendan Eich <bren...@mozilla.org> wrote:
> All praise to Raf et al., my concern is that something synchronous, plus > event loop concurrency and setImmediate, would suffice to bootstrap the > rather more elaborate proposal on top of the simpler O.p.watch like > fundament. > > This is not to say we shouldn't standardize higher-level APIs, and instead > push that off on library authors to write, and users to download. There's a > delicate balance here. We often screw up higher-level abstractions in > annoying ways, but perhaps that risk is worth taking. > > What I'm really getting at is this: why not expose the synchronous > primitive and e.l.c. building blocks as well? > A synchronous observation mechanism provides an attacker too many opportunities for a plan interference attack. If you'll recall, an earlier synchronous proposal died for this reason. Object.observe has been carefully designed to strike a good balance between providing non-malicious code useful new powers without providing attackers significant new attack opportunities. The core principle is that a client of an object can anyway observe changes to observable state asynchronously by polling between turns. And a client of an object, if it receives control during a turn, can poll while it has control. To a first approximation, Object.observe can be understood as an optimization of polling. It is actually more powerful than that, but in ways that are beneficial without IMO creating significant new hazards. > > /be > > Brandon Benvie wrote: > >> I agree on the above with regard to Proxies. They are awesome and allow >> for incredible things, but Object.observe fills a different use case that I >> think is more common at at the user standpoint or at least library >> standpoint. When you look around at the major JS libraries that exist the >> problem they are trying to solve (after DOM normalization) is data-binding. >> Proxy can be used to solve this for new objects or wrapped objects, but >> that's overkill and may have performance consequences, and has no support >> for working with existing objects. Proxy and observe end up filling two >> completely different use-cases, and I would venture to say that observe is >> the one that most people could make better use of if they had it in their >> hands today. >> ______________________________**_________________ >> es-discuss mailing list >> es-discuss@mozilla.org >> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss> >> > ______________________________**_________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss> > -- Cheers, --MarkM
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