Re: [Boost-users] [Serialize] Serialize just the base class ofpolymorphic pointers

Subject: Re: [Boost-users] [Serialize] Serialize just the base class ofpolymorphic pointers
From: Robert Ramey (ramey_at_[hidden])
Date: 2009-04-07 17:09:56

since your BASE isn't abstract - (no = 0) you can do what you want in the 
following way

save
    Plugin *p
    ar << static_cast<BASE *>(p)
load
    BASE *b
    ar >> b

This will get you what you want.

Robert Ramey

Brandon Aubie wrote:
> I have a base class BASE that stores data.  It has a virtual function
> (empty in base class) that determines how this data is calculated, but
> there's no data stored in the derived classes.  In my program, I'll
> load a pluging that is based on BASE and implements the function to
> calculate the data.  Right now I have BOOST_EXPORT_CLASS in the plugin
> header files and I serialize
> boost::serialization::base_object<BASE>(*this) in the derived class.
> This lets me save the serialization to file just fine.
>
> When I load it back in though, my application isn't aware of the
> plugins (I'm just analyzing the data).  But I don't need the plugins,
> since I just need the data.  So when I try to load in my
> serialization, I get an "unregistered class" exception.  Here's how it
> works
>
> /*************** CODE ******************/
>
> class BASE {
> public:
>  vector<double> data;
>  virtual calculate() {};
>
> private:
>    friend class boost::serialization::access;
>    template<class Archive>
>    void serialize(Archive &ar, const unsigned int version) {
>        ar & data;
>    }
> }
>
> class Plugin: public BASE {
> public:
>   virtual calculate() { /* do stuff */ }
>
> private:
>    friend class boost::serialization::access;
>    template<class Archive>
>    void serialize(Archive &ar, const unsigned int version) {
>        ar & boost::serialization::base_object<BASE>(*this);
>    }
> }
>
> BOOST_CLASS_EXPORT(Plugin)
>
> /*************** CODE ******************/
>
>
> Class Plugin is loaded dynamically at runtime via dlopen() on linux.
> So I have a BASE* that points to an instance of A.  When I load in the
> serialized data though, I don't really care about A and would rather
> just have a BASE* that points to an instance of BASE.  Since there's
> no data described in A.
>
> Can I do this somehow?
>
> Thanks