This discussion[1] maybe useful in solving the problem. "things()" member function should be qualified with a reference to prevent it from being called from an

This discussion[1] maybe useful in solving the problem. "things()" member function should be qualified with a reference to prevent it from being called from an rvalue object. [1] https://stackoverflow.com/questions/21861148/what-does-the-single-ampersand-mean-here https://stackoverflow.com/questions/21861148/what-does-the-s...