Re: [Boost-users] [Serialization] shared_ptr to const object

Subject: Re: [Boost-users] [Serialization] shared_ptr to const object
From: Robert Ramey (ramey_at_[hidden])
Date: 2009-12-21 14:14:03

Steven Watanabe wrote:
> AMDG
>
> elizabeta petreska wrote:
>> I just want to say that I managed to solve this problem without
>> creating a temporary , thanks to this thread :
>> http://old.nabble.com/(de)serializing-map%3Cconst-A*%3E-to5538474.html#a5596607<http://old.nabble.com/%28de%29serializing-map%3Cconst-A*%3E-to5538474.html#a5596607>
>>
>> And here it is what I have got in my problem :
>>
>>     boost::shared_ptr<const TT> jj(new TT(5));
>>
>>     {
>>         boost::archive::xml_oarchive oa(ofs);
>>         oa & BOOST_SERIALIZATION_NVP(jj);
>>     }
>>
>>     boost::shared_ptr<const TT> rjj;
>>
>>     {
>>         void* xptr=&rjj;
>>         boost::shared_ptr<TT> *xxptr;
>>         xxptr=static_cast< boost::shared_ptr<TT> * > (xptr);
>>         boost::archive::xml_iarchive ia(ifs);
>>         ia & BOOST_SERIALIZATION_NVP(*xxptr);
>>     }
>>
>
> This is undefined behavior.  I would strongly advise against it
> if there is a reasonable alternative.
>
> In Christ,
> Steven Watanabe

Note that for better or worse, the serialization library does a lot of this 
kind
of thing internally. If fact, a number of key facilities (e.g. export, usage 
of DLLS, etc depend
on behavior which is technically undefined, but necessary to implement them. 
Just
getting them to work at all was a huge challenge.  I doubt that the above
is any more risky than many usages of the library itself.

Robert Ramey