How can I pass variables to a procedurally generated global function in Lua?

Question

I was recently trying to write event callback handlers for my UI system, and I've been having trouble accessing higher-scope variables from a procedurally generated global function.

Here's some sample code to re-create the problem:

gameInstance = {}
gameInstance.State = {}
gameInstance.State.GetPlayerCountry = function()
  local country = {}
  country.GetInterestGroups = function()
    local iglist = {}
    iglist[1] = "ig1";
    iglist[2] = "ig2";
    iglist[3] = "ig3";
    return iglist;
  end;
  return country;
end;


gameState = gameInstance.State;
playerCountry = gameState.GetPlayerCountry();
interestGroups = playerCountry.GetInterestGroups();
for i in ipairs(interestGroups) do
  local elementID = 'Slider' .. i;
  local onClickCallbackID = elementID .. 'Callback';
  print(onClickCallbackID);
  --layout.CreateElementFromTemplate('slider_template', parentElementID);
  --layout.SetOnClickCallback(elementID, onClickCallbackID);
  _G[onClickCallbackID] = function()
    --local layout = layoutController.xmlLayoutProxy;
    print('Testing a dynamic callback ' .. elementID);
  end;
  Slider1Callback();
end;

This produces the following output (quite unexpectedly):

As you can see, my elementID variable isn't being correctly read by my procedural callbacks. This is a problem because my UI framework heavily relies on ids, and the callback system isn't designed to give a callback function the id of the element it is serving as a callback for (it's expected that the function/coder who writes the function knows or has a way of looking it up), and a re-design would be painful, as I'd have to dig into old unmaintained messy C# Unity code written by somebody else that heavily uses reflection, - I'd basically have to re-write the entire event handling portion of the UI library I am using, altering dozenz of classes.

Why is this happening? Is there any way to fix this.