Effective C++2013-04-16 16:29:46

Effective C++ 条款12 13 16
Revert "Effective C++2013-04-16 16:29:46"

This reverts commit 114facffd9abcc8e54e58916686be082203850b3.
虚继承2013-04-20 16:33:56

完成虚继承部分