lua_createtable(L, 0, 3); 创建大小为3的table
  
  lua_pushcfunction(L, lcopy); 将lcopy压栈
  
  lua_setfield(L, -2, "copy");
  
  {
  	copy = lcopy,
  }
  
  ====================================================================
  
  lua_createtable(L, 0, 2); 创建大小为2的table
  
  lua_pushcfunction(L, ldeletewriter),
  lua_setfield(L, -2, "__gc");
  
  lua_pushcfunction(L, lupdate),
  lua_setfield(L, -2, "__call");
  
  table = {
  	__gc = ldeletewriter,
  	__call = lupdate,
  }
  
  luaL_Reg writer[] = {
  	{ "new", lnewwriter },
  	{ NULL, NULL },
  };
  luaL_setfuncs(L, writer, 1);
  将 writer 压入栈顶，并将table作为上值
  
  ====================================================================
  
  lua_createtable(L, 0, 2);
  lua_pushcfunction(L, ldeletereader),
  lua_setfield(L, -2, "__gc");
  lua_pushcfunction(L, lread),
  lua_setfield(L, -2, "__call");
  
  table = {
  	__gc = ldeletereader,
  	__call = lread,
  }
  
  luaL_Reg reader[] = {
  	{ "newcopy", lnewreader },
  	{ NULL, NULL },
  };
  luaL_setfuncs(L, reader, 1);
  将 reader 压入栈顶，并将table作为上值
  
  ====================================================================
  
  {
  	copy = lcopy,
  	writer = ...,
  	reader = ...,
  }
  
  ====================================================================
  
  	luaL_Reg m[] = {
  		{ "pop", lpop },
  		{ "push", lpush },
  		{ "size", lsize },
  		{ NULL, NULL },
  	};
  	luaL_newmetatable(L, "dangge.deque"); 创建一个meta表并压栈
  	lua_pushvalue(L, -1); 复制一个meta表
  	lua_setfield(L, -2, "__index"); meta = {__index = meta}
  	luaL_setfuncs(L, m, 0); meta = {pop = lpop, push = lpush, size = lsize}