Re: ipairs in Lua 5.3.0-alpha

[Andrew Starks <andrew.starks@...>]

On Saturday, August 16, 2014, Dirk Laurie <dirk.laurie@gmail.com> wrote:
> 2014-08-16 16:42 GMT+02:00 Andrew Starks <andrew.starks@trms.com>:
> >
> >
> > On Saturday, August 16, 2014, Dirk Laurie <dirk.laurie@gmail.com> wrote:
> >>
> >> 2014-08-16 16:23 GMT+02:00 Andrew Starks <andrew.starks@trms.com>:
> >>
> >> > What would be most useful to me, would be if ipairs returned all numeric
> >> > key
> >> > / value pairs, in order, regardless of holes.
> >>
> >> I can't see how implementing that in C would be possible in
> >> a cleverer way than iterating over pairs and keeping what you
> >> need. But the Lua extension I thought was off-topic would
> >> do this for you:
> >>
> >>    for k,v in pairs(tbl) if type(k)=='number' do
> >>       ...
> >>    end
> >>
> >
> > Not in order.
>
> Didn't see that. Then you will have to cache everything in a list
> and sort it, since there is no way you can make a table like
> {[130]='a',[292]='b'} etc retrieve the keys in order, even in C.

Yes, and that is what I do now and it works nicely, except that it means quite a bit of code. 

I assert that ipairs is used when order matters. So, thinking about ipairs in terms of it being the ordinal iterator could be a useful mental framework. 

[I often feel the need to state that I'm on a more facile level than most of you. Sometimes a naive point of view is helpful, though...]

Andrew