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- Subject: Proposal to enhance table.remove
- From: Alexander Chernoskutov <alecherov@...>
- Date: Sat, 10 Sep 2022 22:16:41 +0500
***Sorry in advance if this idea has been discussed recently. I did
found the same exact suggestion back from 2011, but the discussion
didn't seem to reach any conclusion.***
I would like to propose a third argument to `table.remove (list [, pos
`count` - number of elements to remove starting from position `pos`
(defaults to 1). All the removed values are returned. [Also, we can
probably allow `count` to be negative.]
Right know there's no good way to remove `count` elements from a table.
One can only write something like this
for i = 1,count do table.remove(t, pos) end
My problem with this approach is grossly unjustified inefficiency.
table.remove itself is O(#t) and the cycle amounts to O(count * #t).
(Worst case scenario is `pos` == 1, `count` == #t which leads to O(#t ^ 2) )
If we add count argument to the library function, the complexity is
going to be limited to O(#t) regardless of `count`.
This, of course, should not break any existing code since the argument
is optional and defaults to the current behaviour.
If necessary, I can provide my implementation. (I'm not doing it right
away because the official FAQ discourages submitting any code.)
With regards, Alex Ch