Re: caching userdata pointers, lua_pushuserdata?

[David Burgess <dburgess@...>]

Why not use lua_pushvalue() ?

On 7/26/05, Kriss <Kriss@xixs.com> wrote:
> 
> 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
> 
> http://XIXs.com -><- http://www.WetGenes.com
> 
> 
>