On Feb 14, 2012, at 4:20 PM, "Tab Atkins Jr." <[email protected]> wrote:
> On Tue, Feb 14, 2012 at 1:10 PM, Dean Landolt <[email protected]> wrote: >> On Tue, Feb 14, 2012 at 3:54 PM, Tab Atkins Jr. <[email protected]> >> wrote: >>> On Sun, Feb 12, 2012 at 7:08 PM, Brendan Eich <[email protected]> wrote: >>>> See the thread containing Dean Landolt's dissent on 'length' being the >>>> best >>>> name: >>>> >>>> https://mail.mozilla.org/pipermail/es-discuss/2011-November/018571.html >>>> >>>> The January 19 2012 meeting notes recorded here: >>>> >>>> https://mail.mozilla.org/pipermail/es-discuss/2012-January/019784.html >>>> >>>> include "At next meeting MarkM will present a tiny API proposal for maps >>>> and >>>> sets." >>> >>> In today's practice, iterables are ducktyped by the presence of a >>> "length" property. >> >> >> IME they're ducktyped by the presence of forEach (this is far from perfect). >> Length has nothing to do with iterability. What about generators? > > I don't want to go looking anything up right now, but I have lots of > memories of things looking for the presence of "length" to denote an > array-like. Not only that, `length` is how ES's own Array methods control iteration. > [].forEach.call({ 0: "bar", 1: "qux" }, function(val) { console.log(val); }); undefined > [].forEach.call({ 0: "bar", 1: "qux", length: 2 }, function(val) { > console.log(val); }); bar qux undefined > > >>> I don't think an "[implication of] metric >>> topology" matters to basically anyone who's not a huge language-design >>> nerd. ^_^ >> >> I'm pretty sure math geeks would disagree. > > We math geeks are also thin on the ground, so the point of my > assertion (that the number of people who care is vanishingly small) > still holds. > > >>> Additionally, having multiple names for the "size of" property makes >>> it more difficult to learn, and more difficult to create generic code. >> >> That's a bold assertion. I'd argue that having two different names for two >> things that are fundamentally different is quite practical. It's especially >> useful for writing generic code ;) > > They're not fundamentally different unless you go to some lengths (pun > not intended) to make them so. "length" is the size of a collection; > it doesn't immediately denote anything about the indexability of said > collection. > > >> But more practically we need different names -- setting length has certain >> expectations that wouldn't hold across all collections. Violating these >> expectations would make things ever more difficult to learn...and generic >> code even harder to write. > > This sounds pretty reasonable. The fact that 'length' is settable on > Array is pretty weird in the first place imo, If you think of `length` in terms of measuring a physical thing, it's not weird at all. > and as you say, it's > nonsensical for Set/Map. Okay, I'm more in favor of 'count' or > something being a readonly on all the collections then, as you > suggested in the thread Brendan linked, so that it can become the "new > length". > > ~TJ > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
