Hierarchy of classes which Xapian can throw as exceptions. 
 
Decide if a Xapian::Error exception should be ignored. 
 
bool already_handled
True if this error has already been passed to an ErrorHandler. 
 
void operator()(Xapian::Error &error)
Handle a Xapian::Error object. 
 
virtual ~ErrorHandler()
We require a virtual destructor because we have virtual methods. 
 
All exceptions thrown by Xapian are subclasses of Xapian::Error. 
 
virtual bool handle_error(Xapian::Error &error)=0
Perform user-specified error handling.