RE: [boost] shared pointer serialization

From: Rozental, Gennadiy (gennadiy.rozental_at_[hidden])
Date: 2004-04-28 11:47:26

> > what if I do not save all of the shared_ptr to the same object?
> 
> Here is a scenario:
> 
> a) a shared_ptr exists and it points to and object which is 
> pointed by 9 other shared_ptrs.
> 
> b) we create and archive and save some objects.  The set 
> objects saved only includes 5 of the shared_ptrs out of the 
> possible 10.
> 
> c) later when we load, we create 5 new shared_ptr and one new 
> object. Object tracking guarantees that only one shared 
> object is created. As each new shared pointer is loaded, the 
> shared count is incremented.  So the new shared pointer is 
> not identical to the original - its equal to 5.
> 
> d) the process (almost?) guarantees that all the shared_ptr 
> are valid in that they all point to shared object and the 
> shared_count is maintained to be the correct number.  The 
> intention is that this process be exception safe
> - I'm not sure that this intention has been realized.

This is about how I expect it to work. But from this description it's
unclear:

1. Why would you need to save counter into archive? After all value 10 has
nothing to do with resulting 5.
2. Why would you need direct access to shared_ptr counter? After all using
regular shared_ptr copy would automatically bump it to proper value.

Gennadiy.