replace std::optional<T*> to std::optional<std::reference_wrapper<T>>

[zyfjeff]

At present, the Object has an interface that returns the type std::optional<T*>. This return type is troublesome for the user. Is the returned pointer pointing to a valid address? In fact, the pointer here is always valid. This would not be a problem if the return type was std::optional<std::reference_wrapper<T>>.

[wbpcode]

/assign

[wbpcode]

I will try land it and make the implementation more clean. 😄

[zyfjeff]

close by #20