tag methods are always functions, so don't need to store a whole object

10 files changed, 161 insertions, 132 deletions

diff --git a/ldebug.c b/ldebug.c
index 8a9a2ca6..f3b92af9 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.c,v 1.43 2000/10/02 20:10:55 roberto Exp roberto $
+** $Id: ldebug.c,v 1.44 2000/10/05 12:14:08 roberto Exp roberto $
 ** Debug Interface
 ** See Copyright Notice in lua.h
 */
@@ -203,12 +203,14 @@ static void lua_funcinfo (lua_State *L, lua_Debug *ar, StkId func) {
 
 
 static const char *travtagmethods (lua_State *L, const TObject *o) {
-  int e;
-  for (e=0; e<IM_N; e++) {
-    int t;
-    for (t=0; t<=L->last_tag; t++)
-      if (luaO_equalObj(o, luaT_getim(L, t,e)))
-        return luaT_eventname[e];
+  if (ttype(o) == LUA_TFUNCTION) {
+    int e;
+    for (e=0; e<TM_N; e++) {
+      int t;
+      for (t=0; t<=L->last_tag; t++)
+        if (clvalue(o) == luaT_gettm(L, t, e))
+          return luaT_eventname[e];
+    }
   }
   return NULL;
 }
diff --git a/ldo.c b/ldo.c
index 281ef22e..11d6c5a6 100644
--- a/ldo.c
+++ b/ldo.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 1.101 2000/10/04 12:16:08 roberto Exp roberto $
+** $Id: ldo.c,v 1.102 2000/10/05 12:14:08 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -142,10 +142,11 @@ static StkId callCclosure (lua_State *L, const struct Closure *cl, StkId base) {
 }
 
 
-void luaD_callTM (lua_State *L, const TObject *f, int nParams, int nResults) {
+void luaD_callTM (lua_State *L, Closure *f, int nParams, int nResults) {
   StkId base = L->top - nParams;
   luaD_openstack(L, base);
-  *base = *f;
+  clvalue(base) = f;
+  ttype(base) = LUA_TFUNCTION;
   luaD_call(L, base, nResults);
 }
 
@@ -163,12 +164,12 @@ void luaD_call (lua_State *L, StkId func, int nResults) {
   Closure *cl;
   if (ttype(func) != LUA_TFUNCTION) {
     /* `func' is not a function; check the `function' tag method */
-    const TObject *im = luaT_getimbyObj(L, func, IM_FUNCTION);
-    if (ttype(im) == LUA_TNIL)
+    Closure *tm = luaT_gettmbyObj(L, func, TM_FUNCTION);
+    if (tm == NULL)
       luaG_typeerror(L, func, "call");
     luaD_openstack(L, func);
-    *func = *im;  /* tag method is the new function to be called */
-    LUA_ASSERT(ttype(func) == LUA_TFUNCTION, "invalid tag method");
+    clvalue(func) = tm;  /* tag method is the new function to be called */
+    ttype(func) = LUA_TFUNCTION;
   }
   cl = clvalue(func);
   ci.func = cl;
diff --git a/ldo.h b/ldo.h
index dab8fc6e..1058d34e 100644
--- a/ldo.h
+++ b/ldo.h
@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.h,v 1.25 2000/09/25 16:22:42 roberto Exp roberto $
+** $Id: ldo.h,v 1.26 2000/10/04 12:16:08 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -25,7 +25,7 @@ void luaD_lineHook (lua_State *L, StkId func, int line, lua_Hook linehook);
 void luaD_callHook (lua_State *L, StkId func, lua_Hook callhook,
                     const char *event);
 void luaD_call (lua_State *L, StkId func, int nResults);
-void luaD_callTM (lua_State *L, const TObject *f, int nParams, int nResults);
+void luaD_callTM (lua_State *L, Closure *f, int nParams, int nResults);
 void luaD_checkstack (lua_State *L, int n);
 
 void luaD_breakrun (lua_State *L, int errcode);
diff --git a/lgc.c b/lgc.c
index 1aca4e20..02ca2794 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lgc.c,v 1.69 2000/10/02 14:47:43 roberto Exp roberto $
+** $Id: lgc.c,v 1.70 2000/10/05 12:14:08 roberto Exp roberto $
 ** Garbage Collector
 ** See Copyright Notice in lua.h
 */
@@ -63,16 +63,6 @@ static void marklock (lua_State *L, GCState *st) {
 }
 
 
-static void marktagmethods (lua_State *L, GCState *st) {
-  int e;
-  for (e=0; e<IM_N; e++) {
-    int t;
-    for (t=0; t<=L->last_tag; t++)
-      markobject(st, luaT_getim(L, t,e));
-  }
-}
-
-
 static void markclosure (GCState *st, Closure *cl) {
   if (!ismarked(cl)) {
     if (!cl->isC)
@@ -83,6 +73,18 @@ static void markclosure (GCState *st, Closure *cl) {
 }
 
 
+static void marktagmethods (lua_State *L, GCState *st) {
+  int e;
+  for (e=0; e<TM_N; e++) {
+    int t;
+    for (t=0; t<=L->last_tag; t++) {
+      Closure *cl = luaT_gettm(L, t, e);
+      if (cl) markclosure(st, cl);
+    }
+  }
+}
+
+
 static void markobject (GCState *st, TObject *o) {
   switch (ttype(o)) {
     case LUA_TUSERDATA:  case LUA_TSTRING:
@@ -269,8 +271,8 @@ static void collectudata (lua_State *L, int all) {
       else {  /* collect */
         int tag = next->u.d.tag;
         *p = next->nexthash;
-        next->nexthash = L->IMtable[tag].collected;  /* chain udata */
-        L->IMtable[tag].collected = next;
+        next->nexthash = L->TMtable[tag].collected;  /* chain udata */
+        L->TMtable[tag].collected = next;
         L->nblocks -= gcsizeudata;
         L->udt.nuse--;
       }
@@ -292,12 +294,13 @@ static void checkMbuffer (lua_State *L) {
 
 
 static void callgcTM (lua_State *L, const TObject *o) {
-  const TObject *im = luaT_getimbyObj(L, o, IM_GC);
-  if (ttype(im) != LUA_TNIL) {
+  Closure *tm = luaT_gettmbyObj(L, o, TM_GC);
+  if (tm != NULL) {
     int oldah = L->allowhooks;
     L->allowhooks = 0;  /* stop debug hooks during GC tag methods */
     luaD_checkstack(L, 2);
-    *(L->top) = *im;
+    clvalue(L->top) = tm;
+    ttype(L->top) = LUA_TFUNCTION;
     *(L->top+1) = *o;
     L->top += 2;
     luaD_call(L, L->top-2, 0);
@@ -313,8 +316,8 @@ static void callgcTMudata (lua_State *L) {
   L->GCthreshold = 2*L->nblocks;  /* avoid GC during tag methods */
   for (tag=L->last_tag; tag>=0; tag--) {  /* for each tag (in reverse order) */
     TString *udata;
-    while ((udata = L->IMtable[tag].collected) != NULL) {
-      L->IMtable[tag].collected = udata->nexthash;  /* remove it from list */
+    while ((udata = L->TMtable[tag].collected) != NULL) {
+      L->TMtable[tag].collected = udata->nexthash;  /* remove it from list */
       tsvalue(&o) = udata;
       callgcTM(L, &o);
       luaM_free(L, udata);
diff --git a/lstate.c b/lstate.c
index 874b35bd..e4e0bc33 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 1.41 2000/09/25 16:22:42 roberto Exp roberto $
+** $Id: lstate.c,v 1.42 2000/09/29 12:42:13 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -73,7 +73,7 @@ lua_State *lua_open (int stacksize) {
   L->rootproto = NULL;
   L->rootcl = NULL;
   L->roottable = NULL;
-  L->IMtable = NULL;
+  L->TMtable = NULL;
   L->last_tag = -1;
   L->refArray = NULL;
   L->refSize = 0;
@@ -103,8 +103,8 @@ void lua_close (lua_State *L) {
   if (L->stack)
     L->nblocks -= (L->stack_last - L->stack + 1)*sizeof(TObject);
   luaM_free(L, L->stack);
-  L->nblocks -= (L->last_tag+1)*sizeof(struct IM);
-  luaM_free(L, L->IMtable);
+  L->nblocks -= (L->last_tag+1)*sizeof(struct TM);
+  luaM_free(L, L->TMtable);
   L->nblocks -= (L->refSize)*sizeof(struct Ref);
   luaM_free(L, L->refArray);
   L->nblocks -= (L->Mbuffsize)*sizeof(char);
diff --git a/lstate.h b/lstate.h
index 9c31349a..2a93f663 100644
--- a/lstate.h
+++ b/lstate.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 1.39 2000/09/25 16:22:42 roberto Exp roberto $
+** $Id: lstate.h,v 1.40 2000/09/29 12:42:13 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -32,6 +32,7 @@ struct Ref {
 
 
 struct lua_longjmp;  /* defined in ldo.c */
+struct TM;  /* defined in ltm.h */
 
 
 typedef struct stringtable {
@@ -59,8 +60,8 @@ struct lua_State {
   stringtable strt;  /* hash table for strings */
   stringtable udt;   /* hash table for udata */
   Hash *gt;  /* table for globals */
-  struct IM *IMtable;  /* table for tag methods */
-  int last_tag;  /* last used tag in IMtable */
+  struct TM *TMtable;  /* table for tag methods */
+  int last_tag;  /* last used tag in TMtable */
   struct Ref *refArray;  /* locked objects */
   int refSize;  /* size of refArray */
   int refFree;  /* list of free positions in refArray */
diff --git a/ltests.c b/ltests.c
index 5ceebcb5..e7464e51 100644
--- a/ltests.c
+++ b/ltests.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ltests.c,v 1.47 2000/10/02 20:10:55 roberto Exp roberto $
+** $Id: ltests.c,v 1.48 2000/10/05 12:14:08 roberto Exp roberto $
 ** Internal Module for Debugging of the Lua Implementation
 ** See Copyright Notice in lua.h
 */
@@ -438,6 +438,16 @@ static int testC (lua_State *L) {
     else if EQ("dostring") {
       lua_dostring(L, luaL_check_string(L, getnum));
     }
+    else if EQ("settagmethod") {
+      int tag = getnum;
+      const char *event = getname;
+      lua_settagmethod(L, tag, event);
+    }
+    else if EQ("gettagmethod") {
+      int tag = getnum;
+      const char *event = getname;
+      lua_gettagmethod(L, tag, event);
+    }
     else if EQ("type") {
       lua_pushstring(L, lua_typename(L, lua_type(L, getnum)));
     }
diff --git a/ltm.c b/ltm.c
index 1dfc8a72..1f0ac830 100644
--- a/ltm.c
+++ b/ltm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ltm.c,v 1.52 2000/10/03 14:27:44 roberto Exp roberto $
+** $Id: ltm.c,v 1.53 2000/10/05 12:14:08 roberto Exp roberto $
 ** Tag methods
 ** See Copyright Notice in lua.h
 */
@@ -17,7 +17,7 @@
 #include "ltm.h"
 
 
-const char *const luaT_eventname[] = {  /* ORDER IM */
+const char *const luaT_eventname[] = {  /* ORDER TM */
   "gettable", "settable", "index", "getglobal", "setglobal", "add", "sub",
   "mul", "div", "pow", "unm", "lt", "concat", "gc", "function",
   "le", "gt", "ge",  /* deprecated options!! */
@@ -36,9 +36,9 @@ static int findevent (const char *name) {
 
 static int luaI_checkevent (lua_State *L, const char *name, int t) {
   int e = findevent(name);
-  if (e >= IM_N)
+  if (e >= TM_N)
     luaO_verror(L, "event `%.50s' is deprecated", name);
-  if (e == IM_GC && t == LUA_TTABLE)
+  if (e == TM_GC && t == LUA_TTABLE)
     luaO_verror(L, "event `gc' for tables is deprecated");
   if (e < 0)
     luaO_verror(L, "`%.50s' is not a valid event name", name);
@@ -50,8 +50,8 @@ static int luaI_checkevent (lua_State *L, const char *name, int t) {
 /* events in LUA_TNIL are all allowed, since this is used as a
 *  'placeholder' for "default" fallbacks
 */
-/* ORDER LUA_T, ORDER IM */
-static const char luaT_validevents[NUM_TAGS][IM_N] = {
+/* ORDER LUA_T, ORDER TM */
+static const char luaT_validevents[NUM_TAGS][TM_N] = {
   {1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1},  /* LUA_TUSERDATA */
   {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},  /* LUA_TNIL */
   {1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1},  /* LUA_TNUMBER */
@@ -67,16 +67,16 @@ int luaT_validevent (int t, int e) {  /* ORDER LUA_T */
 
 static void init_entry (lua_State *L, int tag) {
   int i;
-  for (i=0; i<IM_N; i++)
-    ttype(luaT_getim(L, tag, i)) = LUA_TNIL;
-  L->IMtable[tag].collected = NULL;
+  for (i=0; i<TM_N; i++)
+    luaT_gettm(L, tag, i) = NULL;
+  L->TMtable[tag].collected = NULL;
 }
 
 
 void luaT_init (lua_State *L) {
   int t;
-  luaM_growvector(L, L->IMtable, 0, NUM_TAGS, struct IM, "", MAX_INT);
-  L->nblocks += NUM_TAGS*sizeof(struct IM);
+  luaM_growvector(L, L->TMtable, 0, NUM_TAGS, struct TM, "", MAX_INT);
+  L->nblocks += NUM_TAGS*sizeof(struct TM);
   L->last_tag = NUM_TAGS-1;
   for (t=0; t<=L->last_tag; t++)
     init_entry(L, t);
@@ -84,9 +84,9 @@ void luaT_init (lua_State *L) {
 
 
 int lua_newtag (lua_State *L) {
-  luaM_growvector(L, L->IMtable, L->last_tag, 1, struct IM,
+  luaM_growvector(L, L->TMtable, L->last_tag, 1, struct TM,
                   "tag table overflow", MAX_INT);
-  L->nblocks += sizeof(struct IM);
+  L->nblocks += sizeof(struct TM);
   L->last_tag++;
   init_entry(L, L->last_tag);
   return L->last_tag;
@@ -108,9 +108,9 @@ int lua_copytagmethods (lua_State *L, int tagto, int tagfrom) {
   int e;
   checktag(L, tagto);
   checktag(L, tagfrom);
-  for (e=0; e<IM_N; e++) {
+  for (e=0; e<TM_N; e++) {
     if (luaT_validevent(tagto, e))
-      *luaT_getim(L, tagto, e) = *luaT_getim(L, tagfrom, e);
+      luaT_gettm(L, tagto, e) = luaT_gettm(L, tagfrom, e);
   }
   return tagto;
 }
@@ -130,8 +130,10 @@ void lua_gettagmethod (lua_State *L, int t, const char *event) {
   int e;
   e = luaI_checkevent(L, event, t);
   checktag(L, t);
-  if (luaT_validevent(t, e))
-    *L->top = *luaT_getim(L, t,e);
+  if (luaT_validevent(t, e) && luaT_gettm(L, t, e)) {
+    clvalue(L->top) = luaT_gettm(L, t, e);
+    ttype(L->top) = LUA_TFUNCTION;
+  }
   else
     ttype(L->top) = LUA_TNIL;
   incr_top;
@@ -139,19 +141,26 @@ void lua_gettagmethod (lua_State *L, int t, const char *event) {
 
 
 void lua_settagmethod (lua_State *L, int t, const char *event) {
-  TObject temp;
-  int e;
-  LUA_ASSERT(lua_isnil(L, -1) || lua_isfunction(L, -1),
-             "function or nil expected");
-  e = luaI_checkevent(L, event, t);
+  Closure *oldtm;
+  int e = luaI_checkevent(L, event, t);
   checktag(L, t);
   if (!luaT_validevent(t, e))
     luaO_verror(L, "cannot change `%.20s' tag method for type `%.20s'%.20s",
                 luaT_eventname[e], luaO_typenames[t],
-                (t == LUA_TTABLE || t == LUA_TUSERDATA) ? " with default tag"
-                                                          : "");
-  temp = *(L->top - 1);
-  *(L->top - 1) = *luaT_getim(L, t,e);
-  *luaT_getim(L, t, e) = temp;
+                (t == LUA_TTABLE || t == LUA_TUSERDATA) ?
+                   " with default tag" : "");
+  oldtm = luaT_gettm(L, t, e);
+  switch (ttype(L->top - 1)) {
+    case LUA_TNIL:
+      luaT_gettm(L, t, e) = NULL;
+      break;
+    case LUA_TFUNCTION:
+      luaT_gettm(L, t, e) = clvalue(L->top - 1);
+      break;
+    default:
+      lua_error(L, "tag method must be a function (or nil)");
+  }
+  clvalue(L->top - 1) = oldtm;
+  ttype(L->top - 1) = (oldtm ? LUA_TFUNCTION : LUA_TNIL);
 }
 
diff --git a/ltm.h b/ltm.h
index c6de9e36..f72f9867 100644
--- a/ltm.h
+++ b/ltm.h
@@ -1,5 +1,5 @@
 /*
-** $Id: ltm.h,v 1.16 2000/10/03 14:27:44 roberto Exp roberto $
+** $Id: ltm.h,v 1.17 2000/10/05 12:14:08 roberto Exp roberto $
 ** Tag methods
 ** See Copyright Notice in lua.h
 */
@@ -13,36 +13,36 @@
 
 /*
 * WARNING: if you change the order of this enumeration,
-* grep "ORDER IM"
+* grep "ORDER TM"
 */
 typedef enum {
-  IM_GETTABLE = 0,
-  IM_SETTABLE,
-  IM_INDEX,
-  IM_GETGLOBAL,
-  IM_SETGLOBAL,
-  IM_ADD,
-  IM_SUB,
-  IM_MUL,
-  IM_DIV,
-  IM_POW,
-  IM_UNM,
-  IM_LT,
-  IM_CONCAT,
-  IM_GC,
-  IM_FUNCTION,
-  IM_N          /* number of elements in the enum */
-} IMS;
-
-
-struct IM {
-  TObject int_method[IM_N];
-  TString *collected;  /* list of G. collected udata with this tag */
+  TM_GETTABLE = 0,
+  TM_SETTABLE,
+  TM_INDEX,
+  TM_GETGLOBAL,
+  TM_SETGLOBAL,
+  TM_ADD,
+  TM_SUB,
+  TM_MUL,
+  TM_DIV,
+  TM_POW,
+  TM_UNM,
+  TM_LT,
+  TM_CONCAT,
+  TM_GC,
+  TM_FUNCTION,
+  TM_N          /* number of elements in the enum */
+} TMS;
+
+
+struct TM {
+  Closure *method[TM_N];
+  TString *collected;  /* list of garbage-collected udata with this tag */
 };
 
 
-#define luaT_getim(L,tag,event) (&L->IMtable[tag].int_method[event])
-#define luaT_getimbyObj(L,o,e)  (luaT_getim((L),luaT_tag(o),(e)))
+#define luaT_gettm(L,tag,event) (L->TMtable[tag].method[event])
+#define luaT_gettmbyObj(L,o,e)  (luaT_gettm((L),luaT_tag(o),(e)))
 
 
 #define validtag(t) (NUM_TAGS <= (t) && (t) <= L->last_tag)
diff --git a/lvm.c b/lvm.c
index 7b33be14..48f78d01 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 1.142 2000/10/04 12:16:08 roberto Exp roberto $
+** $Id: lvm.c,v 1.143 2000/10/05 12:14:08 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -116,27 +116,27 @@ void luaV_Lclosure (lua_State *L, Proto *l, int nelems) {
 ** Receives the table at `t' and the key at top.
 */
 const TObject *luaV_gettable (lua_State *L, StkId t) {
-  const TObject *im;
+  Closure *tm;
   int tg;
   if (ttype(t) == LUA_TTABLE &&  /* `t' is a table? */
       ((tg = hvalue(t)->htag) == LUA_TTABLE ||  /* with default tag? */
-        ttype(luaT_getim(L, tg, IM_GETTABLE)) == LUA_TNIL)) { /* or no TM? */
+        luaT_gettm(L, tg, TM_GETTABLE) == NULL)) { /* or no TM? */
     /* do a primitive get */
     const TObject *h = luaH_get(L, hvalue(t), L->top-1);
     /* result is no nil or there is no `index' tag method? */
-    if (ttype(h) != LUA_TNIL ||
-        (ttype(im=luaT_getim(L, tg, IM_INDEX)) == LUA_TNIL))
+    if (ttype(h) != LUA_TNIL || ((tm=luaT_gettm(L, tg, TM_INDEX)) == NULL))
       return h;  /* return result */
     /* else call `index' tag method */
   }
   else {  /* try a `gettable' tag method */
-    im = luaT_getimbyObj(L, t, IM_GETTABLE);
+    tm = luaT_gettmbyObj(L, t, TM_GETTABLE);
   }
-  if (ttype(im) != LUA_TNIL) {  /* is there a tag method? */
+  if (tm != NULL) {  /* is there a tag method? */
     luaD_checkstack(L, 2);
     *(L->top+1) = *(L->top-1);  /* key */
     *L->top = *t;  /* table */
-    *(L->top-1) = *im;  /* tag method */
+    clvalue(L->top-1) = tm;  /* tag method */
+    ttype(L->top-1) = LUA_TFUNCTION;
     L->top += 2;
     luaD_call(L, L->top - 3, 1);
     return L->top - 1;  /* call result */
@@ -155,16 +155,17 @@ void luaV_settable (lua_State *L, StkId t, StkId key) {
   int tg;
   if (ttype(t) == LUA_TTABLE &&  /* `t' is a table? */
       ((tg = hvalue(t)->htag) == LUA_TTABLE ||  /* with default tag? */
-        ttype(luaT_getim(L, tg, IM_SETTABLE)) == LUA_TNIL)) /* or no TM? */
+        luaT_gettm(L, tg, TM_SETTABLE) == NULL)) /* or no TM? */
     *luaH_set(L, hvalue(t), key) = *(L->top-1);  /* do a primitive set */
   else {  /* try a `settable' tag method */
-    const TObject *im = luaT_getimbyObj(L, t, IM_SETTABLE);
-    if (ttype(im) != LUA_TNIL) {
+    Closure *tm = luaT_gettmbyObj(L, t, TM_SETTABLE);
+    if (tm != NULL) {
       luaD_checkstack(L, 3);
       *(L->top+2) = *(L->top-1);
       *(L->top+1) = *key;
       *(L->top) = *t;
-      *(L->top-1) = *im;
+      clvalue(L->top-1) = tm;
+      ttype(L->top-1) = LUA_TFUNCTION;
       L->top += 3;
       luaD_call(L, L->top - 4, 0);  /* call `settable' tag method */
     }
@@ -176,14 +177,15 @@ void luaV_settable (lua_State *L, StkId t, StkId key) {
 
 const TObject *luaV_getglobal (lua_State *L, TString *s) {
   const TObject *value = luaH_getstr(L->gt, s);
-  const TObject *im = luaT_getimbyObj(L, value, IM_GETGLOBAL);
-  if (ttype(im) == LUA_TNIL)  /* is there a tag method? */
+  Closure *tm = luaT_gettmbyObj(L, value, TM_GETGLOBAL);
+  if (tm == NULL)  /* is there a tag method? */
     return value;  /* default behavior */
   else {  /* tag method */
     luaD_checkstack(L, 3);
-    *L->top = *im;
-    ttype(L->top+1) = LUA_TSTRING;
+    clvalue(L->top) = tm;
+    ttype(L->top) = LUA_TFUNCTION;
     tsvalue(L->top+1) = s;  /* global name */
+    ttype(L->top+1) = LUA_TSTRING;
     *(L->top+2) = *value;
     L->top += 3;
     luaD_call(L, L->top - 3, 1);
@@ -194,8 +196,8 @@ const TObject *luaV_getglobal (lua_State *L, TString *s) {
 
 void luaV_setglobal (lua_State *L, TString *s) {
   const TObject *oldvalue = luaH_getstr(L->gt, s);
-  const TObject *im = luaT_getimbyObj(L, oldvalue, IM_SETGLOBAL);
-  if (ttype(im) == LUA_TNIL) {  /* is there a tag method? */
+  Closure *tm = luaT_gettmbyObj(L, oldvalue, TM_SETGLOBAL);
+  if (tm == NULL) {  /* is there a tag method? */
     if (oldvalue != &luaO_nilobject) {
       /* cast to remove `const' is OK, because `oldvalue' != luaO_nilobject */
       *(TObject *)oldvalue = *(L->top - 1);
@@ -213,32 +215,33 @@ void luaV_setglobal (lua_State *L, TString *s) {
     *(L->top+1) = *oldvalue;
     ttype(L->top) = LUA_TSTRING;
     tsvalue(L->top) = s;
-    *(L->top-1) = *im;
+    clvalue(L->top-1) = tm;
+    ttype(L->top-1) = LUA_TFUNCTION;
     L->top += 3;
     luaD_call(L, L->top - 4, 0);
   }
 }
 
 
-static int call_binTM (lua_State *L, StkId top, IMS event) {
+static int call_binTM (lua_State *L, StkId top, TMS event) {
   /* try first operand */
-  const TObject *im = luaT_getimbyObj(L, top-2, event);
+  Closure *tm = luaT_gettmbyObj(L, top-2, event);
   L->top = top;
-  if (ttype(im) == LUA_TNIL) {
-    im = luaT_getimbyObj(L, top-1, event);  /* try second operand */
-    if (ttype(im) == LUA_TNIL) {
-      im = luaT_getim(L, 0, event);  /* try a `global' method */
-      if (ttype(im) == LUA_TNIL)
+  if (tm == NULL) {
+    tm = luaT_gettmbyObj(L, top-1, event);  /* try second operand */
+    if (tm == NULL) {
+      tm = luaT_gettm(L, 0, event);  /* try a `global' method */
+      if (tm == NULL)
         return 0;  /* error */
     }
   }
   lua_pushstring(L, luaT_eventname[event]);
-  luaD_callTM(L, im, 3, 1);
+  luaD_callTM(L, tm, 3, 1);
   return 1;
 }
 
 
-static void call_arith (lua_State *L, StkId top, IMS event) {
+static void call_arith (lua_State *L, StkId top, TMS event) {
   if (!call_binTM(L, top, event))
     luaG_binerror(L, top-2, LUA_TNUMBER, "perform arithmetic on");
 }
@@ -275,7 +278,7 @@ int luaV_lessthan (lua_State *L, const TObject *l, const TObject *r, StkId top)
     luaD_checkstack(L, 2);
     *top++ = *l;
     *top++ = *r;
-    if (!call_binTM(L, top, IM_LT))
+    if (!call_binTM(L, top, TM_LT))
       luaG_ordererror(L, top-2);
     L->top--;
     return (ttype(L->top) != LUA_TNIL);
@@ -287,7 +290,7 @@ void luaV_strconc (lua_State *L, int total, StkId top) {
   do {
     int n = 2;  /* number of elements handled in this pass (at least 2) */
     if (tostring(L, top-2) || tostring(L, top-1)) {
-      if (!call_binTM(L, top, IM_CONCAT))
+      if (!call_binTM(L, top, TM_CONCAT))
         luaG_binerror(L, top-2, LUA_TSTRING, "concat");
     }
     else if (tsvalue(top-1)->u.s.len > 0) {  /* if len=0, do nothing */
@@ -517,7 +520,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       }
       case OP_ADD: {
         if (tonumber(top-2) || tonumber(top-1))
-          call_arith(L, top, IM_ADD);
+          call_arith(L, top, TM_ADD);
         else
           nvalue(top-2) += nvalue(top-1);
         top--;
@@ -527,7 +530,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         if (tonumber(top-1)) {
           ttype(top) = LUA_TNUMBER;
           nvalue(top) = (Number)GETARG_S(i);
-          call_arith(L, top+1, IM_ADD);
+          call_arith(L, top+1, TM_ADD);
         }
         else
           nvalue(top-1) += (Number)GETARG_S(i);
@@ -535,7 +538,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       }
       case OP_SUB: {
         if (tonumber(top-2) || tonumber(top-1))
-          call_arith(L, top, IM_SUB);
+          call_arith(L, top, TM_SUB);
         else
           nvalue(top-2) -= nvalue(top-1);
         top--;
@@ -543,7 +546,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       }
       case OP_MULT: {
         if (tonumber(top-2) || tonumber(top-1))
-          call_arith(L, top, IM_MUL);
+          call_arith(L, top, TM_MUL);
         else
           nvalue(top-2) *= nvalue(top-1);
         top--;
@@ -551,14 +554,14 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       }
       case OP_DIV: {
         if (tonumber(top-2) || tonumber(top-1))
-          call_arith(L, top, IM_DIV);
+          call_arith(L, top, TM_DIV);
         else
           nvalue(top-2) /= nvalue(top-1);
         top--;
         break;
       }
       case OP_POW: {
-        if (!call_binTM(L, top, IM_POW))
+        if (!call_binTM(L, top, TM_POW))
           lua_error(L, "undefined operation");
         top--;
         break;
@@ -574,7 +577,7 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
       case OP_MINUS: {
         if (tonumber(top-1)) {
           ttype(top) = LUA_TNIL;
-          call_arith(L, top+1, IM_UNM);
+          call_arith(L, top+1, TM_UNM);
         }
         else
           nvalue(top-1) = -nvalue(top-1);