https://www.youtube.com/watch?v=e8Cw17p_BiU&list=PL5jc9xFGsL8FWtnZBeTqZBbniyw0uHyaH&index=6

https://www.youtube.com/watch?v=KMSYmY74AEs&list=PLE28375D4AC946CC3&index=4

如果只有copy asignment operator, 那么default construct will be generated as well.

delete function is still counted as a decleration

11更新了03的新规则
在这里插入图片描述

This means that it’s declared when your class is defined, and defined (as inline) when it’s first used in the given translation unit.

用到才会define, 不然只是声明。