问题：
I have a solid understanding of most OO theory but the one thing that confuses me a lot is virtual destructors. 我对大多数面向对象理论有扎实的了解，但令我困惑的一件事是虚拟析构函数。
I thought that the destructor always gets called no matter what and for every object in the chain. 我以为无论链中的每个对象是什么，析构函数总是被调用。
When are you meant to make them virtual and why? 您打算何时将它们虚拟化？为什么？
解决方案：
参考一： https://stackoom.com/question/1vyl/何时使用虚拟析构函数参考二： https://oldbug.net/q/1vyl/When-to-use-virtual-destructors
来源：oschina
链接：https://my.oschina.net/stackoom/blog/3219050