diff --git a/ldo.c b/ldo.c
index 6af8843e..fcec993e 100644
--- a/ldo.c
+++ b/ldo.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 2.29 2005/08/09 19:49:04 roberto Exp roberto $
+** $Id: ldo.c,v 2.30 2005/08/22 18:54:49 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -48,7 +48,7 @@ struct lua_longjmp {
 };
 
 
-static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
+void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop) {
   switch (errcode) {
     case LUA_ERRMEM: {
       setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG));
@@ -82,7 +82,7 @@ static void resetstack (lua_State *L, int status) {
   L->ci = L->base_ci;
   L->base = L->ci->base;
   luaF_close(L, L->base);  /* close eventual pending closures */
-  seterrorobj(L, status, L->base);
+  luaD_seterrorobj(L, status, L->base);
   L->nCcalls = 0;
   L->allowhook = 1;
   restore_stack_limit(L);
@@ -427,10 +427,11 @@ LUA_API int lua_resume (lua_State *L, int nargs) {
     else if (L->ci != L->base_ci)
       return resume_error(L, "cannot resume non-suspended coroutine");
   }
+  luai_userstateresume(L, nargs);
   status = luaD_rawrunprotected(L, resume, L->top - nargs);
   if (status != 0) {  /* error? */
     L->status = cast(lu_byte, status);  /* mark thread as `dead' */
-    seterrorobj(L, status, L->top);
+    luaD_seterrorobj(L, status, L->top);
   }
   else
     status = L->status;
@@ -440,9 +441,8 @@ LUA_API int lua_resume (lua_State *L, int nargs) {
 
 
 LUA_API int lua_yield (lua_State *L, int nresults) {
-  CallInfo *ci;
+  luai_userstateyield(L, nresults);
   lua_lock(L);
-  ci = L->ci;
   if (L->nCcalls > 0)
     luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
   L->base = L->top - nresults;  /* protect stack slots below */
@@ -464,7 +464,7 @@ int luaD_pcall (lua_State *L, Pfunc func, void *u,
   if (status != 0) {  /* an error occurred? */
     StkId oldtop = restorestack(L, old_top);
     luaF_close(L, oldtop);  /* close eventual pending closures */
-    seterrorobj(L, status, oldtop);
+    luaD_seterrorobj(L, status, oldtop);
     L->nCcalls = oldnCcalls;
     L->ci = restoreci(L, old_ci);
     L->base = L->ci->base;
diff --git a/ldo.h b/ldo.h
index e1b27db7..574005a3 100644
--- a/ldo.h
+++ b/ldo.h
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.h,v 2.4 2005/04/25 19:24:10 roberto Exp roberto $
+** $Id: ldo.h,v 2.5 2005/08/22 18:54:49 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -61,6 +61,7 @@ LUAI_FUNC void luaD_growstack (lua_State *L, int n);
 LUAI_FUNC void luaD_throw (lua_State *L, int errcode);
 LUAI_FUNC int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud);
 
+LUAI_FUNC void luaD_seterrorobj (lua_State *L, int errcode, StkId oldtop);
 
 #endif
 
diff --git a/luaconf.h b/luaconf.h
index e623e314..8a57dddd 100644
--- a/luaconf.h
+++ b/luaconf.h
@@ -1,5 +1,5 @@
 /*
-** $Id: luaconf.h,v 1.59 2005/08/15 14:12:32 roberto Exp roberto $
+** $Id: luaconf.h,v 1.60 2005/08/17 18:32:09 roberto Exp roberto $
 ** Configuration file for Lua
 ** See Copyright Notice in lua.h
 */
@@ -670,11 +670,15 @@ union luai_Cast { double l_d; long l_l; };
 
 
 /*
-@@ luai_userstateopen allows user-specific initialization on new threads.
-** CHANGE it if you defined LUAI_EXTRASPACE and need to initialize that
-** data whenever a new lua_State is created.
+@@ luai_userstate* allow user-specific actions on threads.
+** CHANGE them if you defined LUAI_EXTRASPACE and need to do something
+** extra when a thread is created/deleted/resumed/yielded.
 */
-#define luai_userstateopen(L)	((void)0)
+#define luai_userstateopen(L)		((void)0)
+#define luai_userstatefree(L)		((void)0)
+#define luai_userstateresume(L,n)	((void)0)
+#define luai_userstateyield(L,n)	((void)0)
+