New ES6 strawman: Array.prototype.fill and Array.prototype.move

Brian Kardell bkardell at gmail.com
Sun Jun 23 18:18:54 PDT 2013


On Jun 23, 2013 5:12 PM, "Allen Wirfs-Brock" <allen at wirfs-brock.com> wrote:
>
>
> On Jun 23, 2013, at 1:36 PM, Brendan Eich wrote:
>
> > Allen Wirfs-Brock wrote:
> >> See http://wiki.ecmascript.org/doku.php?id=strawman:array_fill_and_movefor a strawman proposal for two new Array methods. These are proposed for
inclusion in ES6.
> >
> > I updated the wiki:
> >
> >
> > Discussion
> >
> > Q: Does anyone know of a rationale for why (start, end) might be a
better design pattern than (start, count) for such operation?
> >
> > A: Array.prototype.slice uses (start, end) where end is a fencepost to
facilitate looping over half-open ranges within a larger range. Spec’ing
count requires subtracting next_start - end, gratuitously. Also,
consistency with slice and range APIs matters. This should be considered
carefully in the design.
>
> Yes, both start,end (slice) and start,count  (splice) currently appears
in Array methods so it isn't obvious which precedent to follow for best
consistency. I could go either way.  It would be nice to have a
utilitarian-based argument for one or the other.  Search result was it
because of the -1.
>
> allen
>
>
>
>
>
> >
> > — /Brendan Eich <mailto:%26%23x62%3B%26%23x72%3B%26%23x65%3B%26%23x6e%3B%26%23x64%3B%26%23x61%3B%26%23x6e%3B%26%23x40%3B%26%23x6d%3B%26%23x6f%3B%26%23x7a%3B%26%23x69%3B%26%23x6c%3B%26%23x6c%3B%26%23x61%3B%26%23x2e%3B%26%23x6f%3B%26%23x72%3B%26%23x67%3B>
2013/06/23 20:31/
> >
> >
> > /be
> >
>
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I would like to propose that .move() smells funny.  It implies things that
are not so.  It actually copies, and, while .copyRange suggestion from the
wiki is better, it really -feels- like .copySlice() which answers the args
question as well.
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