Re: Use lua_State as local variable in C function call, but not to load instructions each time

[Bogdan Harjoc <harjoc@...>]

Hi,

Huang Lin wrote:
> Hi there,
>  
> I use lua in this way in my C program.
>  
> int getPrompt (char* output)
> {
>         lua_State *L = lua_open();  /* create state */
>
>         if (luaL_loadfile(L, "test.lua") || lua_pcall(L, 0, 0, 0))
>         {
>
>         }
>         /// other lua logic to get output
>         lua_close(L);
> }
> By using a local lua_State, the C program can begin the LUA logic from a 
> fresh environment. This is also helpful when the C function, getPrompt, 
> was run in multithread environment that doesn't require LUA related data 
> to be shared/exchanged between threads.
>  
> But it is expensive to load the LUA instructions each time when I just 
> want a local and fresh LUA runtime environment.
>  
> Is it possible to load/compile the LUA scripts once, put the result in 
> the memory, and let the local lua_State(an independent lua universes) 
> use it?
>  
> Thanks,
> Huang Lin
>  

Since luaL_load() pushes the main chunk to the stack, you can store it 
in some
global variable or in the registry, along with the environment (using 
perhaps
getfenv()/setfenv() ) and call it several times later, restoring the env 
each time.

I realise that if you can't reuse the lua_State then this is probably 
all useless.


Cheers!
Bogdan