On Jun 30, 2010, at 10:05 AM, Jürg Lehni wrote:
> I am still interested in hearing more feedback on this. Maybe my examples
> were not so clear?
>
> As more real world example, taken from a UI library that I am working with,
> would look like this:
>
> var stopButton = new ImageButton(this) {
> image: getImage('stop.png'),
> size: buttonSize,
> toolTip: 'Stop Running Scripts',
> onClick: stopAll
> };
>
>
> Again, all the properties from the object literal immediately following the
> constructor call would then be set on the created object.
>
> Rhino allows me to use this already and it has been proven to be very useful
> in many occasions, leading to cleaner and more readable code.
Some of us old-timers were around at Netscape with Norris Boyd when this was
designed and added to Rhino. It was not added to SpiderMonkey, though, for not
terribly compelling reasons.
I remember being concerned about the ASI issue, which requries a [no
LineTerminator here] restricted production. That is still a concern: the TC39
committee doesn't want to add restricted productions without very good reason.
This came up later, via https://bugzilla.mozilla.org/show_bug.cgi?id=253138 --
see https://bugzilla.mozilla.org/show_bug.cgi?id=253138#c7.
https://bugzilla.mozilla.org/show_bug.cgi?id=253138#c10 suggests an operator of
some sort to "merge" the objects.
Another point to note is that [1,2,3] is not equivalent to new Array(3) {0:1,
1:2, 2:3}, because the array initialiser form users the original value of
Array.prototype, and it does not call the current binding of Array as a
constructor.
So, more work needed to avoid a restricted production, at least. A linking
operator or keyword ("with" a la functional record update) would help.
/be
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