On 3/16/07, Janek Kozicki <janek_listy@wp.pl> wrote:
Robert Ramey said: (by the date of Thu, 15 Mar 2007 18:56:25 -0800)
Zach Laine wrote:
I did something stupid with my serialization code. I blithely changed the names of several polymorphic classes everywhere they appeared in the code, since they had moved out of a class into that class's namespace (e.g. SomeNS::View::Primitive became SomeNS::Primitive). Several months later, I discovered that I could no longer read old binary archives, because I was using Boost.Serialization's BOOST_CLASS_EXPORT() macro, and this macro was now registering the Primtive type with the name-string "Primitive", instead of "View::Primitive", which is how it was saved in the oldest archives.
Ouch.
IMHO this is the best example demonstrating that sometimes using a class name as a GUID is not the best idea. If Zach from the very beginning used a custom string (different that the class name) as a GUID, this thing would have never happened. Am I right?
This was my thought as well. In fact, I'm going to switch all our BOOST_CLASS_EXPORT(T) macros to BOOST_CLASS_EXPORT_GUID(T, "[T's canonical name]") macros, and leave a giant note for others to do the same ("Here there be dragons", etc.). In light of this problem, I would say that while use of BOOST_CLASS_EXPORT() is convenient, it is ultimately a maintenance burden. Zach Laine