On Jul 30, 2010, at 2:53 PM, Brendan Eich wrote: > On Jul 30, 2010, at 2:43 PM, felix wrote: > >>> Of course this does not say what the syntax for a meta-programmable >>> iteration construct should be, but laziness suggests "all" is not >>> precisely on target. >> >> so why not make it "for each"? for-each iterates over a stream, and in the >> case of arrays the stream is the array values. > > Reasons not to add each: > > 1. Avoid another contextual keyword (few implemented E4X). > 2. Avoid confusion over what "each" means. > 3. Even assuming we added "each" based on E4X, the objection that |for each > (x in y)| loops would need to cope with y being a proxy that customizes > value-iteration exists. > > Point 3 is Waldemar's objection w.r.t. |for-in| becoming customizable (as it > is in JS1.7 and Python). It applies equally to |for-each-in| given the E4X > precedent of non-proxy object on right of 'in' being enumerated (iterated > over its enumerable keys), and its enumerable keys' values returned. > > One can bikeshed for days on all sorts of vague and wrongly general words > such as "each". Instead, focusing on the right side of "in", providing an > explicit iterator-factory call, seems strictly better.
I think that while "for each ... in" or "for all ... in" is a potentially confusing distinction vs. "for ... in", it still seems less potentially confusing to me than having no distinction at all. Another entry for the bikeshedding pile: "for values ... in". That definitely screams "values, not keys". Regards, Maciej _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
