Yehuda Katz (ph) 718.877.1325
On Mon, Oct 15, 2012 at 12:23 PM, Brendan Eich <bren...@mozilla.org> wrote: > Allen Wirfs-Brock wrote: > >> On Oct 12, 2012, at 2:16 PM, David Herman wrote: >> >> On Oct 12, 2012, at 12:14 PM, Erik >> Arvidsson<erik.arvidsson@**gmail.com<erik.arvids...@gmail.com>> >>> wrote: >>> >>> On Fri, Oct 12, 2012 at 11:16 AM, David Bruant<bruan...@gmail.com> >>>> wrote: >>>> >>>>> Firefox has implement a Map/Set.prototype.size *method* to query the >>>>> number >>>>> of mapping/elements. >>>>> It's not in the strawman. It appears in the latest draft, though >>>>> weirdly >>>>> enough Map.prototype.size is a function with an unused argument. >>>>> What about making it an getter instead of a function? I guess we also >>>>> don't >>>>> need the extra parens to request for Map#keys, Map#values, Map#items. >>>>> >>>> For keys, values and items I think they are cleaner as methods since >>>> they return a new iterator every time. >>>> >>> Agreed. >>> >>> Dave >>> >>> >> I buy making Map/Set size an accessor. This will be the first such >> property in the ES specification and it would be good to have some >> guidelines to help us make consistent decisions about using accessors in >> the future. >> >> Erik and Tab floated a couple reasons why items/keys/values should not be >> accessors. >> >> Does anybody want to take a crack at writing up a complete set of design >> rules for when a built-in property should/shouldn't be defined as an >> accessor? >> > > Simpler is better. Tab, Arv, and others hit the big one. Here's a first > cut: > > * get-only accessor for non-writable property must be idempotent, > effect-free. > > * get/set accessor may have effects on 'set' (see the DOM) but only on the > receiver object (and unobservably, any children that become garbage, e.g. > when trimming .length on an array-like). > DOM methods like `innerHTML=` seem to violate this particular wording (but perhaps not the spirit?) > * get/set accessors should reflect as such. This means Array.length gets a > legacy dispensation, and __proto__ needs poisoning. > > * anything else is a method. > > /be > > ______________________________**_________________ > 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
