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- Subject: Re: Struggling with userdata concepts
- From: Michal Kottman <k0mpjut0r@...>
- Date: Sun, 28 Aug 2011 13:00:13 +0200
2011/8/28 Jeff Smith <email@example.com>:
> Does my understanding sound correct on that ? That was expected from the
> limitation you mentioned ?
Yes, this is the implication of modifying the metatable of light
userdata - you have only one (global) metatable for light userdata.
> OK, so that kind of makes light userdata pretty much useless for real world
> examples where more than one structure type is needed, or am I missing
> something here, it sounds too big a limitation so I am doubting my
> understanding is correct.
As I said, it is useful for opaque foreign (non-Lua) types like
handles, which you use in a non-object-oriented way (i.e. get them as
return values and pass them as parameters to functions).
> I guess I need to look at using full userdata now as an alternative way to
> go, I didnt really follow Michals follow up post , but I have only read it
> once so far, I need to re-read that one
Sorry for not being clear, I wanted to be brief. I recommend you read
the book Programming in Lua, mainly the chapter about user-defined
types in C , where everything you seem to need is explained step by
step (actually, I recommend reading the whole book when you have the