Re: [Boost-users] [Serialization] purpose of GUID

From: Ingo Nolden (nuttygraphics_at_[hidden])
Date: 2007-05-15 15:15:34

Hi,

I am a bit confused about the purpose of GUID. My understanding was, 
that it is a user defined id for a class, so that the serialization 
mechanism knows what types to instanciate on load. I somehow assumed 
it to be a replacement (or equivalent) of the numbers in the class_id 
attributes.

by inserting:

BOOST_CLASS_EXPORT_GUID( bus_schedule, "BusSchedule" );

I'd expected to find something like:

<schedule class_id="BusSchedule"

in the xml file, but I get only:

<schedule class_id="1"

I know that another purpose of the BOOST_CLASS_EXPORT family of 
macros is to instanciate the <Archive, T*> pairs, but what is the 
"BusSchedule" string then for.

If my assumption was right, where do I have to place the macros 
exactly then. I tried at the end of the header with the classes. I 
then tried at the beginning, after the includes. That didn't work 
unless I forward declared the classes (no surprise really).

Also, is there some docs/tutorials/further reading on xml archives. I 
am probably going to make my own archive, and need to understand more 
about the mechanism.

Thanks for your help,

Ingo