Robert, Thanks for the quick response. I have ensured that the serialization for each type is located in exactly one place. The header files where the serialization code resides for the derived classes are not global, that is, our build system is set up to ensure that no other library or DLL can reference them. I believe that I can make the serialization completely independent and contained inside the DLL without much difficulty. However, unless I statically link the serialization library, I don't think I can prevent the macro: BOOST_CLASS_EXPORT_GUID( class, "ClassNameText" ) from initializing the global table inside the serialization DLL (which is dynamically linked). I noticed that when I tried to use the other registration technique you describe, register_type<T>(), this also calls the registration code in the serialization DLL on load, so that doesn't solve the problem. It doesn't seem very practical to serializing in/out a prototype of each derived class into the archive initially because it would increase the archive size by a lot. Too bad there isn't a mechanism for creating a registration table specific to the DLL where the classes are serialized. If the global table was of the following structure: using namespace std; map< HMODULE, map >; Then the above macro would simply use AfxGetInstanceHandle (in the case of windows, I am unsure what the corresponding calls in other OS's would be), to pass the HMODULE handle. Ed -----Original Message----- From: Robert Ramey [mailto:ramey@rrsd.com] Sent: Monday, November 13, 2006 8:24 AM To: boost-users@lists.boost.org Subject: Re: [Boost-users] [Serialization] unexpected assert registeringclasses Having serialization code in DLLS has raised some stick issues. The basic problem is the existence of a global table of information about types being serialized. Among other thngs, this global type table contains the export string name (GUID) that is shared among programs to identify the type. This table also points to functions via a virtual function mechnamism to implementations required by serialization. Entries are added to this table when code is loaded and deleted when code is unloaded. in version 1.33 I included the indicated assert - as it seemed to me that this must be unique. I was concerned that multiple entries in the table might point to different function implementations - as indeed they will. So I included this assertion. This started to create problems as you have found. Also I've now come to thnk that the having multiple entries for the same type is harmless - and difficult to avoid in the presence of dynamically loaded/unloaded DLLS. So in 1.34 - I commmented out the assertion. In addition, I've augmented the code to make sure that the correct entry in the table is deleted when the corresponding DLL is unloaded. So I believe that starting in 1.34 this problem will be resolved. I really don't know for sure because its very hard to come up with a good test for this. So, I think this problem is addressed. But in the face of dynamically loaded DLLs - which are not all guarenteed to be in sync ( some could have older versions of code), I think that the best policy would be to be sure that serialzation code for a particular type should be found in one and only one place. Also, doing this will result in smaller DLLS and applications. Doing this requires that one explicitly orgranize his code so to achieve this. This means avoiding instantiation of serialization code in applications and by explicitly instantiation such code in the DLLS. The closest guide I have for doing this is demo_pimpl which shows how to do this. Robert Ramey "Reusser, Edward" wrote in message news:5E916BAE1732F344BAFD713DF2373479016EA054@SV-MSG-01.amer.actel.com.. . I am using the boost 1.33.1 distribution, and the xml_iarchive and xml_oachive to serialize a rather deep and complex data structure to xml. I am using make_nvp directly in all cases (not the macro). I am sometimes getting the following assert (line 71 in extended_type_info.cpp) when I load previously serialized data: assert( lookup(eti) == m_self->m_map.end() ); It seems obvious that what is happening is that somehow I am calling self_register more than once for a specific class. Tracing through the code however I am puzzled exactly how this could happen, since the registration should only happen once when the libraries are loaded. This never happens on save by the way, only on load. It also never happens if I do the save, followed by a load immediately. It only happens if I do the save, shut down the application, then load the data. I have verified that the loaded data is a bit by bit equivalent in both cases. The best that I can come up with is that I am loading the serialization library as a side effect of calling LoadLibrary at runtime. So I am linking in the serialization library after everything else has been loaded and is running. But again, none of the libraries are ever unloaded, and the load sequence should always be the same. The actual situation is that I have a library . call it Library A, which is linked to libraries B, and C. The library A is being linked using the LoadLibrary call, each of libraries B are C are linked to the boost serialization library. In each of libraries B, and C, I have used the macro: BOOST_CLASS_EXPORT_GUID( class, "ClassNameText" ) To define all of my classes I am serializing, including all classes that I am serializing using shared_ptr's. I was thinking originally that the problems were all shared_ptr's of classes that are derived from enable_shared_from_this<T>, but I am no longer confident that has anything to do with it. In fact, truth be told, I have no idea if any of the above has anything to do with the problem. When I commented out the assertion, everything seems to work just fine, except now I am getting a stack overflow on very complex hierarchies in the spirit parser (again, load only), but the simpler ones seem to work repeatedly without any problems. I have no doubt that the assertion was added there for a reason, so I hate to comment it out without finding out what else I might have broken. Edward Reusser Principal Engineer Actel Corporation (650) 318-4972 The information contained in or attached to this email may be subject to the Export Administration Regulations (EAR), administered by the U.S. Department of Commerce, or the International Traffic in Arms Regulations (ITAR), administered by the U.S. Department of State, and may require an export license from the Commerce or State Department prior to its export. 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