Could you not do this with a promise? If not, what's missing in promise that you could do with "lazy"? Sorry if I've missed the whole premise
On Thu, 31 Aug 2017 at 19:09 Andrea Giammarchi <[email protected]> wrote: > the following is how I usually consider lazy values > > ```js > class Any { > _lazy(name) { > switch (name) { > case 'uid': return Math.random(); > // others ... eventually > } > } > get uid() { > var value = this._lazy('uid'); > // from now on, direct access > Object.defineProperty(this, 'uid', {value}); > return value; > } > } > > const a = new Any; > a.uid === a.uid; // true > ``` > > If I understand correctly your proposal is to use Lazy as generic > descriptor, is that correct ? > > ```js > Object.defineProperty({}, 'something', new Lazy(function (val) { > return this.shakaLaka ? val : 'no shakaLaka'; > })); > ``` > > ??? > > If that's the case I see already people confused by arrow function > in case they need to access the context, > plus no property access optimization once resolved. > > It's also not clear if such property can be set again later on (right now > it cannot) > 'cause lazy definition doesn't always necessarily mean inability to > reassign. > > What am I missing/misunderstanding? > > Regards > > > > On Thu, Aug 31, 2017 at 2:21 PM, Isiah Meadows <[email protected]> > wrote: > >> It'd be really nice if lazy values made it into the spec somehow. I've >> already found myself using things like this [1] quite a bit, and I've >> also found myself frequently initializing properties not on first >> access. >> >> [1]: >> https://gist.github.com/isiahmeadows/4c0723bdfa555a1c2cb01341b323c3d4 >> >> As for what would be a nice API, maybe something like one of these? >> >> ```js >> class Lazy<T> { >> constructor(init: () => T); >> get(): T; // or error thrown >> } >> >> function lazy<T>(init: () => T): () => T; // or error thrown >> >> function lazy<T>(init: () => T): { >> get(): T; // or error thrown >> } >> ``` >> >> Alternatively, syntax might work, with `do` expression semantics: >> >> ```js >> const x = lazy do { ... } >> // expose via `x.get()` or just `x()` >> ``` >> >> ----- >> >> Isiah Meadows >> [email protected] >> >> Looking for web consulting? Or a new website? >> Send me an email and we can get started. >> www.isiahmeadows.com >> _______________________________________________ >> 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 >
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
