Re: 'oldindex' metamethod?

[Javier Guerra Giraldez <javier@...>]

On Fri, Sep 19, 2014 at 11:17 AM, John Hind <john.hind@zen.co.uk> wrote:
> Admittedly
> some interpretations of the last case might involve some scanning back, if
> you do not want
> to permit holes at the top of the sequence - but that is a little esoteric


not esoteric at all.

imagine you have a 100,000 element array, then decide to keep only the
first 500.  the obvious way would be:

for i=501, #t do
    t[i] = nil
end

on each iteration, the #t would stay as before on 100,000, until the
very last, where it suddenly would have to scan back 99,500 elements
to find the new end.


-- 
Javier