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Re: Lua 5.2 creating globals with userdata

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On10.04.2012 04:51, James Norton wrote:
[);
// clear the stack
lua_pop(L, lua_gettop(L));
}

test.lua:7: attempt to index global 'x' (a userdata value)

My question is, why does line 4 work correctly, while line 7 complains about the global being userdata? What is the difference between the = assignment on line 3 and the lua_setglobal in my Objective C code?

Thanks in advance for any suggestions.

-James


I don't think there is any difference how metatables are invoked in this two cases, actually if you didn't declared "line" as local than it is a global as well.
I think that the problem lies in the order in which createGlobal and luaopen_display_lib is called. You have to make sure that luaopen_display_lib is called before createGlobal otherwise the luaL_getmetatable in lineSetup will get you a nil value. This would cause the global "Runtime" to have no metatable. If a userdata has no metatable with the function __newindex set you will exactly get the error message you have.

--
Thomas

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