C++临时对象

http://blog.sina.com.cn/s/blog_7b3dad5b0100trnf.html

http://www.cnblogs.com/liyiwen/archive/2009/12/02/1615711.html

http://www.cnblogs.com/liyiwen/archive/2009/12/03/1616627.html

http://www.programlife.net/cpp-return-value-optimization.html