Re: [Boost-users] [Any] inconsistent return types of any_cast overloads

Subject: Re: [Boost-users] [Any] inconsistent return types of any_cast overloads
From: Arne Vogel (avogel_at_[hidden])
Date: 2013-12-04 04:58:34

On 03.12.2013 00:01, Krzysztof Czainski wrote:
> 2013/12/2 Antony Polukhin <antoshkka_at_[hidden] 
> <mailto:antoshkka_at_[hidden]>>
>
>     You are absolutely right: ValueType&& any_cast(any&&) was not a
>     good idea and it may break code that accepts result by const
>     reference.
>     Making it ValueType any_cast(any&&) would be more correct.
>
>     I'll fix that as soon as the migration to the GIT will be finished.
>
>     Great thanks for finding, investigating and reporting this issue!
>
>     Created ticket #9462 : https://svn.boost.org/trac/boost/ticket/9462
>

Thanks a lot!
>
>
> That said, what do you gain by doing:
>   const auto& vec = boost::any_cast<std::vector<int>>(makeVec());
> instead of
>   const auto vec = boost::any_cast<std::vector<int>>(makeVec());
> ?
>
> Regards,
> Kris

In C++11 with a moveable type, probably not much. I don't quite remember 
why I wrote the code like this - it could have been out of habit since 
in C++98 using a reference may save a copy, though I guess an optimizing 
compiler had already been allowed to elide it.

Regards,
Arne