caching userdata pointers, lua_pushuserdata?

[Kriss <Kriss@...>]

I  was just thinking about tidying up some code and want to do the 
following.

cache a pointer returned from lua_touserdata() on the C side (I am 
already doing this anyway)

at some point later on, push that userdata onto the stack to be used as 
a table look up key, I can guarantee that the userdata will not have 
been GCd at this point. At the moment I am using a unique integer as a 
table key, but it would be simpler to use the userdata instead.

however there is no lua_pushuserdata()

Is it safe just to use a modified version of lua_newuserdata() that 
doesnt allocate any new userdata but takes a previously allocated 
pointer and pushes it on the stack?

EG  some untested 5.0 code :)

LUA_API void lua_pushuserdata (lua_State *L, void *data) {
 lua_lock(L);
 luaC_checkGC(L);
 setuvalue(L->top, ((Udata *)(data))-1);
 api_incr_top(L);
 lua_unlock(L);
}

or is there some more magic surrounding userdata I should be aware of.

--

Kriss

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