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Re: ECMAScript and chaining

From: Anne van Kesteren <annevk@annevk.nl>
Date: Thu, 22 Nov 2012 13:32:27 +0100
Message-ID: <CADnb78jeDN8qXL_F0QH-KUfhDe2wT4aVfibZaOzieqnTRdGz5w@mail.gmail.com>
To: Rick Waldron <waldron.rick@gmail.com>
Cc: "public-script-coord@w3.org" <public-script-coord@w3.org>
On Thu, Nov 22, 2012 at 3:31 AM, Rick Waldron <waldron.rick@gmail.com> wrote:
> On Wed, Nov 21, 2012 at 5:26 PM, Anne van Kesteren <annevk@annevk.nl> wrote:
>> I was wondering if the plan of TC39 is to start returning the object
>> on which a method was invoked if that method would otherwise just
>> return undefined. E.g. this seems to be what Object.freeze() and
>> Object.preventExtensions() do. It's also a somewhat popular API idiom
>> in jQuery and the like (see also method chaining, fluent interface).
> I'm not sure what you mean by "start"—this is already the prevailing
> practice. APIs either return an expected specified value/object, the target
> object (in the case of static built-ins, eg. Object.freeze(o); // o ) or a
> new specified object (eg. Array.prototype.{ filter, map } etc.).

Well e.g. Date seems  to work differently (e.g. setHours returns
milliseconds rather than just the Date object), and only the Object
examples you give match the definition I gave and since those are
relatively new I thought I'd raise the question.

>> (The reason I'm asking is that I just WONTFIXED two bugs asking for
>> that stating that ECMAScript did not have this pattern either and I
>> was confronted with the above.
> Links?


>> I had been looking at Map.set() myself.)
> The ES6 Map, Set and WeakMap API specifications are still in development and
> probably shouldn't be used to make decisions like this.

Why not? Patterns used for new APIs typically show the trend.

> In this particular case there is no rationale documented for these not
> returning the object they are called from, so it's still open for
> discussion, ie. Map.prototype.set, Set.prototype.add and
> WeakMap.prototype.set.

We'll see I guess.

Received on Thursday, 22 November 2012 12:32:55 UTC

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