LuaObjectType.lua

function LuaObjectType(obj)
  local t = rawget(obj, "luaObjectType")
  if t == nil then
    --[[No way to avoid a pcall unfortunately]]
    local success, help = pcall(function(obj) return obj.help() end, obj)
    local luaObjectType
    if not success then
      --[[Extract type from error message]]
      t = string.sub(help, 1, string.find(help, " ") - 1)
    else
      --[[Extract type from help message]]
      t = string.sub(help, 10, string.find(help, ":") - 1)
    end
    rawset(obj, "luaObjectType", t)
  end
  return t
end

--[[This is a magic string used by factorio to identify LuaObjects]]
isluaobjectmagic = "802384732948701238470123"
function extendedtype(obj)
  local t = type(obj)
  if t == "table" and obj.isluaobject == isluaobjectmagic and
    --[[In addition to the magic, verify it really has the expected userdata and hidden metatable]]
    type(obj.__self) == "userdata" and getmetatable(obj) == "private" then
    return LuaObjectType(obj)
  end
  return t
end