智能指针
https://blog.csdn.net/runner668/article/details/80539221
shared_ptr的循环引用所导致的内存泄漏
面试题:
https://blog.csdn.net/xy_cpp/article/details/81750575
RAII和右值引用
https://blog.csdn.net/Poisx/article/details/85161071