Improve luaH_initmetatable

src/ltable.cpp

@@ -643,19 +643,22 @@ Table *luaH_new (lua_State *L) {
 
 #ifndef PLUTO_NO_DEFAULT_TABLE_METATABLE
 void luaH_initmetatable (lua_State *L, Table *t) {
+  lua_pushnil(L); /* space on the stack where the metatable will go */
   if (ttisnil(&G(L)->table_mt)) {
+    /* create metatable */
     Table *table_mt = luaH_new(L);
     sethvalue(L, &G(L)->table_mt, table_mt);
-    lua_pushnil(L);
+    /* assign to stack value */
     sethvalue(L, s2v(L->top.p - 1), table_mt);
+    /* set __index */
     lua_pushstring(L, "__index");
     lua_getglobal(L, "table");
     lua_settable(L, -3);
   }
   else {
-    lua_pushnil(L);
     sethvalue(L, s2v(L->top.p - 1), hvalue(&G(L)->table_mt));
   }
+  /* set stack value as metatable and pop */
   t->metatable = hvalue(s2v(L->top.p - 1));
   lua_pop(L, 1);
 }