C++值类别, move, perfect forward

推荐看链接顺序看，第一个链接很好地讲述了值类别地特性，图形很好理解。第二个链接介绍常见值类别的示例，帮助熟悉。第三个链接是第二个链接的补充，让你理解为什么需要std::move以及perfect forward。第四个链接比第三个链接讲解得要全面一些。第五个链接是Scott Meyers大师讲解的视频。

[1] https://blog.knatten.org/2018/03/09/lvalues-rvalues-glvalues-prvalues-xvalues-help/

[2] https://github.com/jeaye/value-category-cheatsheet/blob/vs-colors/value-category-cheatsheet.pdf

[3] https://blog.jeaye.com/2017/03/19/xvalues/

[4] http://thbecker.net/articles/rvalue_references/section_01.html

[5] https://channel9.msdn.com/Shows/Going+Deep/Cpp-and-Beyond-2012-Scott-Meyers-Universal-References-in-Cpp11