Re: [Boost-users] [Serialization] Boost 1.33 serialization constproblem

Hi Robert, On Wed, Dec 13, 2006 at 08:29:40AM -0800, Robert Ramey wrote:

I would be very interested in getting to the bottom of the problem. This would likely result in a small tweak which would make the library more portable. Of course I realise that this is not that easy. Note that I test here with gcc 3.3 under cywin. So I would be hopeful that its easily fixable. I don't know what version of boost your using, but it may already be fixed in a later version.

It looks like the problem is fixed (or at least, workaround-ed). When I change string serialize(const base * const b) to string serialize(base * const b) the problem goes away (I don't get the segfault anymore). I ran the regression tests on the suse (gcc 3.3.3) machine and the serialization tests all pass (except for test_static_warning which gives a warn, but I guess that is what's supposed to happen). I am going to use the workaround (remove the first 'const') and consider this thread closed. Except when you want to investigate some more, I'll be glad to help, but then I need specific instructions on what to test because this is getting a bit over my head ... For completeness I included the original message once more at the bottom of this post. Regards and thanks for your suggestions, Oscar -- Original Message: currently I am trying to get serialization to work. It worked well when I was using boost 1.32, but since I upgraded to 1.33 I'm having some problems. In short; I have an abstract base class and a derived class. I try to serialize/deserialize the derived class through a pointer to the base +class. This worked well when I was using 1.32. When I upgraded to 1.33 I got the static assert which trapped the 'saving non const error' (I hope this makes sense ..). So I fixed it by following instructions from other posts dealing with the same problem (basically just by changing 'base *b' to +'const base * const b'). The fix resolved the compile error, only now I'm getting a segfault at runtime. The segfault happens during deserialization (when trying to 'reconstruct' the original object). The funny thing is, I've tested it on a system (suse enterprise system 9, gcc 3.3.3) and it chrashes. On another system (gcc version 4.0.3 (Ubuntu 4.0.3-1ubuntu5)) it works fine. I reproduced the problem in a very small program located at the end of this post. Maybe someone can have a look at the code and tell me whether there are obvious problems with my code or not. If I know for sure that my code should run correctly, I'll just move on to an other linux distro .. Thanks in advance, Oscar #include #include #include #include #include<iostream> #include<sstream> using namespace std; class base { public: virtual void do_it() const = 0; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int){ cout << "serializing base" << endl; } }; class derived: public base { public: derived(int field1, string field2){ _field1 = field1; _field2 = field2; } virtual void do_it() const { cout << "doing it with " << _field1 << " and " << _field2 << endl; } private: friend class boost::serialization::access; derived(){}; virtual ~derived(){}; template<class Archive> void serialize(Archive & ar, const unsigned int){ cout << "derived being serialized" << endl; ar & boost::serialization::base_object<base>(*this); ar & _field1; ar & _field2; } int _field1; string _field2; }; BOOST_IS_ABSTRACT(base); BOOST_CLASS_EXPORT(derived); string serialize(const base * const b){ stringstream str; boost::archive::text_oarchive oa(str); oa << b; return str.str(); } base *deserialize(string s){ stringstream str(s); base *b; boost::archive::text_iarchive ia(str); ia >> b; return b; } int main(){ base *d1 = new derived(52,"a string"); d1->do_it(); string serialized = serialize(d1); base *d2 = deserialize(serialized); d2->do_it(); return 0; }