On Mon, Jan 23, 2012 at 5:37 AM, Herby Vojčík <[email protected]> wrote:
> Allen Wirfs-Brock wrote: > >> The following is just speculation...One possible such bottleneck >> might be whole object allocation. A JS clone function probably would >> have to allocate an empty object and then dynamically populate it by >> adding properties one at a time. A native implementation is more >> like to have the ability to examine a complete object and create, in >> a single primitive operation, a new object with all of the same >> properties as the original object. In other words, a native >> implementation of deep clone is likely to use some sort of shallow >> clone operation is that not available to pure JS code. This suggest >> that a better way to get faster deep cloning functions is to make a >> native shallow clone function available to JS code. >> > > +1, nice. > Well, to see if this is the bottleneck, one needs to benchmark, first. > > But I feel the need for shallow clone in the language. Such API should be > there, and if needed, with native implementation as well. > > As part of the HTML5 specification, there is the structured clone algorithm<http://www.w3.org/TR/html5/common-dom-interfaces.html#safe-passing-of-structured-data> whose primary use case is web workers. It has already been implemented in Chrome and Firefox, I believe. Not sure if that might be a good place to start in possibly exposing that as part of JavaScript. If I were to make a feature request here, instead of a clone that might not be terribly useful, I would love to see some better support for Clojure style persistent data structures <http://clojure.org/data_structures#Data Structures-Maps (IPersistentMap)>. I know that's a bit of a long shot, but for all the uses of deep cloning I can think of, I feel like persistent data structures are much nicer, and harder to implement in JS. - Russ
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