From 1d6ebce2969d3bfe406633fd8e284ff187ce00f2 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 18 Jun 2009 15:59:18 -0300
Subject: [PATCH] new function 'lua_version' (so that 'checkversion' can be
 implemented in the auxiliary library)

---
 lapi.c   | 14 ++++++--------
 lstate.c |  4 ++--
 lstate.h |  4 ++--
 lua.h    |  5 ++---
 4 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/lapi.c b/lapi.c
index f6e8b034..dd8a96ac 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.81 2009/06/17 18:38:54 roberto Exp roberto $
+** $Id: lapi.c,v 2.82 2009/06/18 16:36:40 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -129,13 +129,11 @@ LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) {
 }
 
 
-LUA_API void lua_checkversion_ (lua_State *L, int version) {
-  lua_lock(L);
-  if (version != LUA_VERSION_NUM)
-    luaG_runerror(L, "app./library not compiled with header " LUA_VERSION);
-  if (G(L)->nilobjp != luaO_nilobject)
-    luaG_runerror(L, "application using multiple Lua VMs");
-  lua_unlock(L);
+static const lua_Number l_version = LUA_VERSION_NUM;
+
+LUA_API const lua_Number *lua_version (lua_State *L) {
+  if (L == NULL) return &l_version;
+  else return G(L)->version;
 }
 
 
diff --git a/lstate.c b/lstate.c
index c6ca5b9b..3268209e 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.54 2009/04/28 19:04:36 roberto Exp roberto $
+** $Id: lstate.c,v 2.55 2009/06/01 19:09:26 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -208,7 +208,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   setnilvalue(registry(L));
   luaZ_initbuffer(L, &g->buff);
   g->panic = NULL;
-  g->nilobjp = luaO_nilobject;
+  g->version = lua_version(NULL);
   g->gcstate = GCSpause;
   g->rootgc = obj2gco(L);
   g->sweepstrgc = 0;
diff --git a/lstate.h b/lstate.h
index 6751c0a1..783e51cf 100644
--- a/lstate.h
+++ b/lstate.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 2.43 2009/04/17 22:00:01 roberto Exp roberto $
+** $Id: lstate.h,v 2.44 2009/06/01 19:09:26 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -148,9 +148,9 @@ typedef struct global_State {
   TValue l_registry;
   struct lua_State *mainthread;
   UpVal uvhead;  /* head of double-linked list of all open upvalues */
+  const lua_Number *version;  /* pointer to version number */
   struct Table *mt[NUM_TAGS];  /* metatables for basic types */
   TString *tmname[TM_N];  /* array with tag-method names */
-  const TValue *nilobjp;  /* pointer to nil object (to check consistency) */
 } global_State;
 
 
diff --git a/lua.h b/lua.h
index aa242e8e..edeafe7a 100644
--- a/lua.h
+++ b/lua.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lua.h,v 1.238 2009/06/15 19:51:31 roberto Exp roberto $
+** $Id: lua.h,v 1.239 2009/06/17 17:49:44 roberto Exp roberto $
 ** Lua - An Extensible Extension Language
 ** Lua.org, PUC-Rio, Brazil (http://www.lua.org)
 ** See Copyright Notice at the end of this file
@@ -118,8 +118,7 @@ LUA_API lua_State *(lua_mainthread) (lua_State *L);
 LUA_API lua_CFunction (lua_atpanic) (lua_State *L, lua_CFunction panicf);
 
 
-LUA_API void lua_checkversion_ (lua_State *L, int version);
-#define lua_checkversion(L)	(lua_checkversion_(L, LUA_VERSION_NUM))
+LUA_API const lua_Number *lua_version (lua_State *L);
 
 
 /*