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