On Wed, Dec 5, 2012 at 10:06 AM, Nathan Wall <nathan.w...@live.com> wrote:
> > Date: Tue, 4 Dec 2012 11:03:57 -0800 > > From: bren...@mozilla.org > > > Subject: Re: (Map|Set|WeakMap)#set() returns `this` ? > > > > Allen Wirfs-Brock wrote: > > > It's less clear which is the best choice for JS. > > > > Cascading wants its own special form, e.g., Dave's > > mustache-repurposed proposal at > > > > https://blog.mozilla.org/dherman/2011/12/01/now-thats-a-nice-stache/ > > > > so one can write cascades without having to be sure the methods involved > > follow an unchecked |this|-returning convention. > > > I really like this possibility. Is there any way of the monocle-mustache > making it into ... say, ES7? > > If so, it would seem wrong to ever return `this`. Sounds like you get the > best of both worlds to me! > Yes, monocle-mustache is very cool, especially Dave's proposed version here, but this: obj.{ prop = "val" }; ...has received negative feedback, because developers want colon, not equal, but colon is to "define" as equal is to "assign". eg. What does this do? elem.{ innerHTML: "<p>paragraph</p>" }; Most developers would naturally assume that this sets elem.innerHTML to "<p>paragraph</p>", but it actually results in a [[DefineOwnProperty]] of innerHTML with {[[Value]]: "<p>paragraph</p>" , [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: true}, which would blow away the accessor descriptor that was previously defined for elem.innerHTML (ie. the one that would convert "<p>paragraph</p>" to a node and insert it into the DOM. So the obvious choice is to use "=" instead of ":" because it correctly connotes the assignment behaviour—except that developers complained about that when we evangelized the possibility. Monocle-mustache is simply not a replacement for return this because chaining mutation methods is not the sole use case. Please review the use cases I provided earlier in the thread. There is simply too much real world evidence (widely adopted libraries (web) and modules (node)) in support of return-this-from-mutation-method to ignore, or now go back on, a base criteria for including the pattern in newly designed built-in object APIs. Rick
_______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
