Problems with luaL_checkuserdata

["Tom Miles" <Tom@...>]

Hi there,

I've been trying to add some form of type safety with my use of
representing pointers in my C++ app with lightuserdata, using
lua_newmetatable, and luaL_checkuserdata etc.  This works in most
instances, but I have an odd situation that I don't know what to do
about.

I have this code in my script:

local region_details = nil
local map = nil

function InitRegionMap(theatre, faction)
	region_details = CampaignUI.RegionsInTheatre(theatre, faction)
	
	map = UIImage(region_details.Map)	
	
	map:SetComponentTexture(Address, 0)

	...
end

The RegionsInTheatre call returns a table of information of which one
field is a value called "Address" that is a userdata storing a pointer
to a "REGION" class, the UIImage is a class wrapped with Lunar, and
Address is a global userdata assigned with a userdata value of type
"COMPONENT".  Before I added the checkuserdata, this all worked fine,
when I read out Address in the SetComponentTexture and do a
lua_touserdata() it works fine, however when I use luaL_checkuserdata it
seems to get confused about which "Address" variable is being used.
I.e. it checks the region_details.Address value, not the global value. 

The error I get when calling luaL_checkuserdata is:

"calling 'SetComponentTexture' on bad self (COMPONENT expected, got
userdata)"

If I put print("Map", Address) before and after the region_details
assignment, I get:

Map	COMPONENT (0x0228f885c)
Map	REGION (0x0228f885c)

As far as I know I don't do anything wrong passing tables back to Lua
from my app. Does anyone have any ideas about what's going on here?  I'm
using Lua 5.1, and I've already fallen foul of the "no virtual indices"
issue, but can't for the life of me figure out what I'm doing wrong.

Thanks for any help,

Tom




 
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