string contatenation handles conversion of integers to strings +

floats always format as floats (with decimal dot or exponent)

lauxlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lauxlib.c,v 1.248 2013/03/21 13:54:57 roberto Exp roberto $
+** $Id: lauxlib.c,v 1.249 2013/04/25 13:53:13 roberto Exp roberto $
 ** Auxiliary functions for building Lua libraries
 ** See Copyright Notice in lua.h
 */
@@ -737,15 +737,10 @@ LUALIB_API int luaL_len (lua_State *L, int idx) {
 LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {
   if (!luaL_callmeta(L, idx, "__tostring")) {  /* no metafield? */
     switch (lua_type(L, idx)) {
-      case LUA_TNUMBER: {
-        if (lua_isinteger(L, idx)) {
-          lua_Integer n = lua_tointeger(L, idx);
-          lua_pushfstring(L, "%I", n);
-        }
-        else {
-          lua_Number n = lua_tonumber(L, idx);
-          lua_pushfstring(L, "%f", n);
-        }
+      case LUA_TNUMBER: {  /* concatenate with empty string to convert */
+        lua_pushvalue(L, idx);
+        lua_pushliteral(L, "");
+        lua_concat(L, 2);
         break;
       }
       case LUA_TSTRING:

lobject.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lobject.c,v 2.64 2013/05/26 14:43:35 roberto Exp roberto $
+** $Id: lobject.c,v 2.65 2013/05/27 17:42:38 roberto Exp roberto $
 ** Some generic functions over Lua objects
 ** See Copyright Notice in lua.h
 */
@@ -282,14 +282,11 @@ const char *luaO_pushvfstring (lua_State *L, const char *fmt, va_list argp) {
         break;
       }
       case 'd': {
-        setivalue(L->top++, va_arg(argp, int));
+        setivalue(L->top++, cast_int(va_arg(argp, int)));
         break;
       }
       case 'I': {
-        char buff[LUA_MAXINTEGER2STR];
-        lua_Integer i = cast(lua_Integer, va_arg(argp, lua_Integer));
-        int l = lua_integer2str(buff, i);
-        pushstr(L, buff, l);
+        setivalue(L->top++, cast_integer(va_arg(argp, lua_Integer)));
         break;
       }
       case 'f': {

lvm.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.170 2013/05/26 14:47:51 roberto Exp roberto $
+** $Id: lvm.c,v 2.171 2013/05/27 12:43:37 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -32,6 +32,10 @@
 #define MAXTAGLOOP	100
 
 
+/* maximum length of the conversion of a number to a string */
+#define MAXNUMBER2STR	50
+
+
 int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
   lua_assert(!ttisfloat(obj));
   if (ttisinteger(obj)) {
@@ -47,12 +51,19 @@ int luaV_tostring (lua_State *L, StkId obj) {
   if (!ttisnumber(obj))
     return 0;
   else {
-    char s[LUAI_MAXNUMBER2STR];
-    lua_Number n;
+    char buff[MAXNUMBER2STR];
     int len;
-    (void)tonumber(obj, &n);
-    len = lua_number2str(s, n);
-    setsvalue2s(L, obj, luaS_newlstr(L, s, len));
+    if (ttisinteger(obj))
+      len = lua_integer2str(buff, ivalue(obj));
+    else {
+      len = lua_number2str(buff, fltvalue(obj));
+      if (strpbrk(buff, ".eE") == NULL) {  /* no marks that it is a float? */
+        buff[len++] = '.';  /* add a '.0' */
+        buff[len++] = '0';
+        buff[len] = '\0';
+      }
+    }
+    setsvalue2s(L, obj, luaS_newlstr(L, buff, len));
     return 1;
   }
 }