How would this work when the getter lives on a prototype? (like most builtin getters) Would it install the memoized value on `this`, or on the object that contains the getter? Would it use [[Set]] or [[Define]]?
On Tue, Jun 12, 2018 at 12:13 AM, Aadit M Shah <aaditms...@fastmail.fm> wrote: > Hello TC39, > > I recently opened an issue <https://github.com/tc39/ecma262/issues/1223> in > the tc39/ecma262 <https://github.com/tc39/ecma262> repository, proposing > a new syntax for lazy getters, and I was directed to the CONTRIBUTING > <https://github.com/tc39/ecma262/blob/master/CONTRIBUTING.md> page which > stated that I should start a conversation on this mailing list. > > So, my feature proposal is to have syntactic sugar for creating lazy > getters > <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get#Smart_self-overwriting_lazy_getters>. > To summarize my original proposal (which you can read by following the very > first link above), I find that creating lazy getters is very verbose. For > example, consider: > > const take = (n, xs) => n === 0 ? null : xs && { > head: xs.head, > get tail() { > delete this.tail; > return this.tail = take(n - 1, xs.tail); > } > }; > > My proposed solution is to add a new keyword lazy to the language. This > keyword can only be used as a prefix to longhand property names in object > initializers, and it defers the execution of the value expression until the > property is accessed. In short, it's just syntactic sugar for lazy getters: > > const take = (n, xs) => n === 0 ? null : xs && { > head: xs.head, > lazy tail: take(n - 1, xs.tail) > }; > > This is purely syntactic sugar. The semantics of this new syntax would > remain the same as that of the desugared syntax. In particular, calling > Object.getOwnPropertyDescriptor(list, "tail") would return an accessor > descriptor before accessing list.tail and a data descriptor afterwards. > > Furthermore, there are other advantages of having this syntactic sugar. > For example, creating cyclic data structures becomes much easier. Examples > are provided in my original proposal which is linked above. Hope to hear > your thoughts on this. > > Regards, > Aadit M Shah > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > >
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