Re: Using Lua and C with a Garbage Collector

["Todor Totev" <umbra.tenebris@...>]

In Lua 5.1 it is trivial to change the memory management.
Acording the manual, the function to create lua state
receives as an argument a function that manages the memory:

  lua_State *lua_newstate (lua_Alloc f, void *ud);

In manual paragraph 3.7:

  typedef void * (*lua_Alloc) (void *ud,
                               void *ptr,
                               size_t osize,
                               size_t nsize);

Perhaps your one will be something like:

static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
  (void)ud;     /* not used */
  (void)osize;  /* not used */
  if (nsize == 0) {
    GC_FREE(ptr);  /* ANSI requires that free(NULL) has no effect */
    return NULL;
  }
  else
    return GC_REALLOC(ptr, nsize);
}

though I'm not expert in using Hans's GC.

If you are using 5.0 - you must re-define some preprocessor macros but
I have never done this before.

Regards,
Todor

On Wed, 15 Mar 2006 01:07:07 +0200, SevenThunders <mattcbro@earthlink.net>  
wrote:

> Unfortunately it is not trivial to attempt to use both techniques at the
> same time.  For example I have a C library that uses garbage collection
> (Hans Boehm et. al.) to manage a complex tree-like data structure.  I  
> wish
> to expose the C library to Lua so that I can script a lot of my test
> routines and perform debugging in LUA.  The problem is that the Hans  
> Boehm
> gc utilities can not see any of the C pointers that are being held in Lua
> and thus all my C objects are eventually collected even though I am still
> 'using' them.
>
> Is there any clean way to do this?  The solutions I can think of all have
> issues.