Re: A Question of Notation

[Dirk Laurie <dpl@...>]

On Sun, Dec 19, 2010 at 04:16:12PM +0200, steve donovan wrote:
> 
> > However, there is still __call available, which, as Luiz pointed out
> > in the slice thread on 2010-12-15, allows the syntax ls{1,4,6}.
> 
> __call works well on the right-hand side, but can't be coerced into
> working on the left-hand side; indexing is the only operator that has
> that desirable property.
> 

For that, you could use a two-argument call: 
    ls({1,4,6},{10,40,60})

setmetatable(ls,{__call = 
    function(self,slice,newval)
        if newval==nil then
            local s={}
            for i,k in ipairs(slice) do s[i]=self[k] end
            return s
        else for i,k in ipairs(slice) do self[k]=newval[i] end
        end
    end })

Maybe disallow nil in newval to avoid the dreaded 'holy' arrays?

Dirk