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- Subject: Re: Lua 5.3 Suggestion: extend lua_(get|set)uservalue() to associate userdata-to-userdata
- From: Sean Conner <sean@...>
- Date: Sun, 1 Dec 2013 19:41:20 -0500
It was thus said that the Great Sir Pogsalot once stated:
> Currently you can only associate a lua table with a userdata through
> lua_setuservalue() -- I wish you could also associate userdata.
> Not sure if this isn't already possible with some other function, but what
> I think I need is to be able to associate one userdata with another for
> collection -- or just a bit of memory to be collected when the one
> Lua-exposed userdata become unreferenced?
> I have a project where I create userdata from a third-party lib -- I cannot
> change its structure, I must expose it to Lua as userdata (that's it). I
> want to keep private information about that userdata but I don't want to
> keep track of its deallocation from C, I just want to associate it with the
> userdata I expose to Lua and have the private data available through
> getuservalue() and I want it deallocated by the GC when the exposed
> userdata becomes unreferenced.
> To me, it would feel less 'to the point' to contain that userdata within a
> table to then associate with the original userdata that's created for me.
> It would feel less readable and sort of ugly to lua_getuservalue() and
> then fetch the first sequence index for the userdata I need containing my
> privates (tee hee).
> Is this an acceptable suggestion or am I off my rocker?
What's wrong with this approach?
struct foo base;
/* ... */
struct myfoo *p = lua_newuserdata(sizeof(struct myfoo));
p->private1 = 1;
p->private2 = 2;
/* ... */
That is, wrap a larger structure around the structure from the third party
lib and store your private data there?