From dba17070ac2a6a54079b0b935635377545a3b764 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 17 Jun 2004 11:06:52 -0300
Subject: [PATCH] optional error for accesss to undefined variables/fields

---
 lauxlib.c |  4 +++-
 lstate.c  |  3 ++-
 lua.c     | 25 ++++++++++++++++---------
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/lauxlib.c b/lauxlib.c
index 765065c5..e1890780 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lauxlib.c,v 1.114 2004/06/02 13:50:46 roberto Exp roberto $
+** $Id: lauxlib.c,v 1.115 2004/06/02 19:06:14 roberto Exp roberto $
 ** Auxiliary functions for building Lua libraries
 ** See Copyright Notice in lua.h
 */
@@ -243,6 +243,8 @@ LUALIB_API void luaL_openlib (lua_State *L, const char *libname,
     if (lua_isnil(L, -1)) {  /* no? */
       lua_pop(L, 1);
       lua_newtable(L);  /* create it */
+      if (lua_getmetatable(L, LUA_GLOBALSINDEX))
+        lua_setmetatable(L, -2);  /* share metatable with global table */
       lua_pushvalue(L, -1);
       /* register it with given name */
       lua_setglobal(L, libname);
diff --git a/lstate.c b/lstate.c
index db4efa03..f8f3f148 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.7 2004/05/31 18:51:50 roberto Exp roberto $
+** $Id: lstate.c,v 2.8 2004/06/02 19:09:36 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -87,6 +87,7 @@ static void f_luaopen (lua_State *L, void *ud) {
   setbit(L->marked, FIXEDBIT);
   stack_init(L, L);  /* init stack */
   sethvalue(L, gt(L), luaH_new(L, 0, 4));  /* table of globals */
+  hvalue(gt(L))->metatable = luaH_new(L, 0, 0);  /* globals metatable */
   sethvalue(L, registry(L), luaH_new(L, 4, 4));  /* registry */
   luaS_resize(L, MINSTRTABSIZE);  /* initial size of string table */
   luaT_init(L);
diff --git a/lua.c b/lua.c
index 112a20cc..d57db025 100644
--- a/lua.c
+++ b/lua.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lua.c,v 1.126 2004/05/31 18:51:50 roberto Exp roberto $
+** $Id: lua.c,v 1.127 2004/06/16 20:22:43 roberto Exp roberto $
 ** Lua stand-alone interpreter
 ** See Copyright Notice in lua.h
 */
@@ -251,6 +251,14 @@ static void manual_input (void) {
 }
 
 
+static int checkvar (lua_State *l) {
+  const char *name = lua_tostring(l, 2);
+  if (name)
+    luaL_error(l, "attempt to access undefined variable `%s'", name);
+  return 0;
+}
+
+
 #define clearinteractive(i)	(*i &= 2)
 
 static int handle_argv (char *argv[], int *interactive) {
@@ -290,6 +298,13 @@ static int handle_argv (char *argv[], int *interactive) {
           print_version();
           break;
         }
+        case 'w': {
+          if (lua_getmetatable(L, LUA_GLOBALSINDEX)) {
+            lua_pushcfunction(L, checkvar);
+            lua_setfield(L, -2, "__index");
+          }
+          break;
+        }
         case 'e': {
           const char *chunk = argv[i] + 2;
           clearinteractive(interactive);
@@ -313,14 +328,6 @@ static int handle_argv (char *argv[], int *interactive) {
             return 1;  /* stop if file fails */
           break;
         }
-        case 'c': {
-          l_message(progname, "option `-c' is deprecated");
-          break;
-        }
-        case 's': {
-          l_message(progname, "option `-s' is deprecated");
-          break;
-        }
         default: {
           clearinteractive(interactive);
           print_usage();