New function 'luaL_openselectedlibs'

Makes it easier to start Lua with only some standard libraries.

ltests.c

@@ -1178,31 +1178,15 @@ static lua_State *getstate (lua_State *L) {
 
 
 static int loadlib (lua_State *L) {
-  static const luaL_Reg libs[] = {
-    {LUA_GNAME, luaopen_base},
-    {"coroutine", luaopen_coroutine},
-    {"debug", luaopen_debug},
-    {"io", luaopen_io},
-    {"os", luaopen_os},
-    {"math", luaopen_math},
-    {"string", luaopen_string},
-    {"table", luaopen_table},
-    {"T", luaB_opentests},
-    {NULL, NULL}
-  };
   lua_State *L1 = getstate(L);
-  int i;
-  luaL_requiref(L1, "package", luaopen_package, 0);
+  int what = luaL_checkinteger(L, 2);
+  luaL_openselectedlibs(L1, what);
+  luaL_requiref(L1, "T", luaB_opentests, 0);
   lua_assert(lua_type(L1, -1) == LUA_TTABLE);
   /* 'requiref' should not reload module already loaded... */
-  luaL_requiref(L1, "package", NULL, 1);  /* seg. fault if it reloads */
+  luaL_requiref(L1, "T", NULL, 1);  /* seg. fault if it reloads */
   /* ...but should return the same module */
   lua_assert(lua_compare(L1, -1, -2, LUA_OPEQ));
-  luaL_getsubtable(L1, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
-  for (i = 0; libs[i].name; i++) {
-    lua_pushcfunction(L1, libs[i].func);
-    lua_setfield(L1, -2, libs[i].name);
-  }
   return 0;
 }