RE: C++ exceptions in persistent streams (patch!)

[erik_ohrnberger]

While reviewing the code in engine.cpp, I noticed that there were multiple
types of exceptions:

        ost::Exceptions
                |
                V
        ost::PersistException
                |
                V
        ost::Engine::Exception

It seems to be that Engine::Engine is the only method that throws a
PersistException.  Shouldn't it also throw an Engine::Exception for
consistency?