RE: ipairs_remove - remove items from array while iterating it

[Thijs Schreijer <thijs@...>]

> 
> Well noted! Also including the fix by Ashwin Hirchi (I love this list!)
> 
> local function ipairs_remove(tbl)
>    local i = 0
>    local shiftback = 0
>    local remove = function()
>       shiftback = shiftback + 1
>       i = i - 1
>    end
>    return function()
>       i = i + 1
>       if shiftback > 0 then
>          tbl[i] = tbl[i+shiftback]
>       end
>       if tbl[i] ~= nil then
>          return i, tbl[i], remove
>       end
>       for n = 1, shiftback-1 do
>          tbl[i+n] = nil
>       end
>       return nil
>    end
> end
> 

This contains some nasty side effects when not finishing the loop (return, break, or goto). Only when the loop finishes the remaining elements are cleared. So if you don't finish, they get duplicated. If you modify the code to clear them while looping, then breaking the loop results in a hole in the list (possibly even worse).

So I think the remove() function should use table.remove() to clear the entry to prevent those sideeffects

Having said that, I think the most elegant solution is backward traversal, as Pasi Mankinen already mentioned

Thijs