emplace or/and boost::in_place

[Kojoley]

Is there a reason why boost::variant does not support in place object construction? The std::variant has emplace<T>(...) though.

[apolukhin]

There were no requests to implement it until now :)

[dpelle]

I would also like to have this. I use ICU UnicodeString type in boost::variant, and UnicodeString is expensive to copy or move. So boost::variant::emplace(…) would help to improve performances.