Re: I dont understand all those discussions.

[Martin <eden_martin_fuhrspam@...>]

On 16-07-21 12:50 PM, Russell Haley wrote:
> Perhaps posting an example for people to follow would help lessen some
> of the "noise"?

As stated somewhere earlier, to implement arrays with nils inside you
just need to define __len metamethod. This sketch demonstrates one of
possible implementations of this idea.

-----
local empty_func = function() end
--( Implement yourself:
local assert_table = empty_func
local is_number = function() return true end
local is_integer = function() return true end
--)

local get_max_idx =
  function(t)
    assert_table(t)
    local result
    for k, v in pairs(t) do
      if is_number(k) and is_integer(k) then
        if not result or (k > result) then
          result = k
        end
      end
    end
    return result
  end

local length_func =
  function(t)
    local mt = getmetatable(t)
    return mt.array_length
  end

local to_array =
  function(t, length)
    length = length or get_max_idx(t) or 0
    setmetatable(
      t,
      {
        is_array = true,
        array_length = length,
        __len = length_func,
      }
    )
  end

-- Demo:
local t = {nil, nil, 3, nil, 5}
to_array(t)
for i = 1, #t do
  print(i, t[i])
end
-----