[boost] Re: [serialization] problem deserializing vectors

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-09-30 00:52:04

Robert Ramey wrote:

>>The problem arises when deserializing vector of classes which private
>>default ctor. Even though class has "friend class
>>boost::serialization::access", I get compile errors.
> 
> <smip ...>
> 
> Your example intrigued me and raised an number of interesting questions.
> I tried to compile your program and got the same result on my system
> then started to think about it.
> 
> The idea that one might have a private default constructor has never
> occurred to me.  

Interesting! When I was experimenting with serialization of pointers, I
failed to declare default ctor, got error, and immediately though "why
don't add it to private section". It worked, and I though it was an
excellent design. If it's not intentional, it's still very good ;-)

> Your example:
> 
>>    vector<V> v;
>>    oa << v;
> 
> creates an empty vector of objects of type v.  A slightly more realistic
> example would be
> 
>     vector<V> v;
>     V v_element;
>     v.push_back(v_element);
>     oa << v;
> 
> This cases would break even before considering the serialization.
> On the other hand the following example is concievable
> 
>     vector<V> v;
>     V v_element(0)
>     v.push_back(v_element);
>     oa << v;
> 
> which I believe fairly illustrates the situtation which concerns you.

Yes, that's exactly what I wanted. 

> The situation of non default constructors is already addressed
> for objects serialized through pointers.  But I've failed to
> address it for other objects.
> 
> I will consider  the best way of handling this.

Thanks!

- Volodya