Re: Re:[boost] Formal review: serialization

From: Robert Ramey (ramey_at_[hidden])
Date: 2004-04-21 00:27:45

I just realized I skipped something

Vladimir Prus wrote:

> 
> ** Custom archive creation **
> 
> I've tried to create a custom archive class (in fact,
> polymorphic_oarchive),
> and got some comments.
> 

> - Documentation says the derived class must provide operator<< and method
> 'load'. It also says there common_iarchive::operator<<. I wonder why the
> derived class should provide operator<<. Can't base operator call 'load'
> directly?
> 

common_iarchive has no operator<<

'load' is called by the library to load primitives - its generally not
called by the << operator unless one wants to bypass the serialization
system entirely.

Perhaps, my usage of load_override was confusion.  I use load_override in
order to work around the lack of partial template function ordering.  Were
it not for this, load_override would not exist.  This is an implementation
artifact.  Load on the other hand is the function used to load primitives.  

> - Even if not, why derived operator<< should have
> 
>      return * This();
> 
> not plain "return *this"? After all, we're in most derived object
> 

No we are not.

The class hierarchy is

common_iarchive
   base_text_oarchive
       text_oarchive_impl
           text_oarchive

in my archives, the operator<< is a member of base_text_oarchive.  If I want
the << operator to return a reference to a text_oarchive NOT
basae_text_oarchive.

The archives included are models of the trivial_archive.  However, the
desire to factor things out in a convenient way makes them less transparent
than I would prefer.

Robert Ramey