[Boost-users] Re: Serialization, shared_ptr and namespaces

From: Robert Ramey (ramey_at_[hidden])
Date: 2005-05-03 20:36:40

I concede this is somewhat confusing.   I made the shared_ptr as a case
study and several people helped me out with issues such as this.  I don't
know if all of them have been address.

Its better and worse.

1.33 will have much simpler and robust implementation of shared_ptr (and
weak_ptr) serialization based on work done by Martin Ecker.  I believe it
will address these problems.

Also, the requirement that serializations be placed in a particular
namespace will be relaxed and ADL will work as expected in all cases.

I'm currently making it work on the older compilers.  I still have pending
the issue of backward compatibility so it will be a while yet.

As to your particular issue, I'll have to consider it

Jan Eickmann wrote:
> Hello,
>
> sorry to bump this but I still haven't found a solution or any
> information on how to use shared_ptr together with serialization.
>
> Anybody can shed some light on this?
>
> Thanks a lot,
>
> Jan Eickmann
>
> Jan Eickmann wrote:
>> Hi,
>>
>> I'm trying to serialize a list of shared_ptr's to objects.
>>
>> Here's a summary of the code I have:
>>
>> namespace MyNamespace
>> {
>>
>> class B
>> {
>> //implementation plus standard serialization function
>> };
>>
>> class A
>> {
>> private:
>>     list< shared_ptr<B> > myBs;
>> public:
>>     template<class Archive>
>>     void serialize(Archive & ar, const unsigned int version)
>>     {
>>         ar & BOOST_SERIALIZATION_NVP(myBs);
>>     }
>> };
>>
>> }
>>
>> If I just try to serialize it, I get an unregistered_class
>> exception. So I think I have to use
>> BOOST_SHARED_POINTER_EXPORT(_GUID) to register the shared_ptr.
>>
>> When I include this inside the namespace (please note that the error
>> messages are from my real code, so they have slightly other names:
>>
>> BOOST_SHARED_POINTER_EXPORT(B)
>>
>> I get this:
>>  f:\xenocide\xenocide\src\common\simulation\simulation.h(108) : error
>> C2059: syntax error : 'string'
>> f:\xenocide\xenocide\src\common\simulation\simulation.h(108) : error
>> C2146: syntax error : missing ';' before identifier
>> 'BOOST_CLASS_EXPORT_GUID'
>> f:\xenocide\xenocide\src\common\simulation\simulation.h(108) : error
>> C2059: syntax error : 'string'
>> f:\xenocide\xenocide\src\common\simulation\simulation.h(109) : error
>> C2143: syntax error : missing ';' before '}'
>>
>> When I put it outside the namespace I have to use a fully qualified
>> name including the namespace for class B, so it becomes
>>
>> BOOST_SHARED_POINTER_EXPORT(MyNamespace::B)
>>
>> Then I get (not Xenocide is here what MyNamespace is in my example):
>> f:\xenocide\xenocide\src\common\simulation\simulation.h(115) : error
>> C2653: '__shared_ptr_Xenocide' : is not a class or namespace name
>> f:\xenocide\xenocide\src\common\simulation\simulation.h(115) : error
>> C2653: '__shared_ptr_Xenocide' : is not a class or namespace name
>>
>> I also tried various combinations with
>> BOOST_SHARED_POINTER_EXPORT_GUID but it didn't help.
>>
>> Can someone explain to me how I have to declare shared_ptr's in order
>> for them to work with boost::serialization? I was unable to find some
>> more indepth documentation.
>>
>> Thanks,
>>
>> Jan Eickmann