July 2006 - Boost-users - lists.preview.boost.org

manually calling constructor?
by bringiton bringiton 24 Jul '06

24 Jul '06

Is it possible to manually call the constructor of an object. It is possible to call the destructor (a trick i found from std::vector<T>::pop_back()) I stepped through the std::vector<T>::push_back() to find how they call the constructor for memory that has already been allocated, but I could not follow the code. Test3 t; t.~Test3(); // OK t.Test3(); // compile error

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shared_ptr compile error ms vc++ 8
by bringiton bringiton 24 Jul '06

24 Jul '06

boost::shared_ptr<int> p(new std::string); In MS VC++ 6, the above will throw the following compile error: >>error C2440: 'initializing' : cannot convert from 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > *' to 'int *' The above is not very useful because it catches the error in the shared_ptr.hpp file. However, it is OK because because the compiler also has a reference to my line of code above: >>see reference to function template instantiation '__thiscall boost::shared_ptr<int>::boost::shared_ptr<int>(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > *)' being compiled The above is all good. I however do not get the luxury of the additional reference in MS VC++ 8. Instead I just get the initial reference to shared_ptr.hpp. This makes it extremely difficult to track where the error because I have many pages that use the shared_ptr. - Can anyone suggest how I can get the 2nd reference to my own code in MS VC++ 8. - Am I missing something obvious? - BTW, in vc++ 8 i'm viewing the errors in a list (instead of the text dump). - I may need to look at the text dump to get the 2nd reference but was wondering if there was an easier solution - Sorry, I dont have vc++ 8 in front of me to give you the error

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Re: [Boost-users] serialization on const member and map<const CLASS*, CLASS>
by Cheok Yan Cheng 24 Jul '06

24 Jul '06

Please take note that even the following simplest form won't work. Here is the full source code. Any suggestion? Thank you very much! #include <iostream> #include <sstream> #include <fstream> using namespace std; #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> class dd { private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & i; } int i; }; class dummy { public: dummy() : d(0){} ~dummy(){} private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & const_cast<dd *>(d); } const dd *d; }; int main() { const dummy w; dummy r; // make an archive std::ofstream ofs("dummy"); boost::archive::text_oarchive oa(ofs); oa << w; std::ifstream ifs("dummy"); boost::archive::text_iarchive ia(ifs); ia >> r; } c:\Documents and Settings\yccheok\Desktop\xxx\main.cpp(34): error C2679: binary '&' : no operator found which takes a right-hand operand of type 'dd *' (or there is no acceptable conversion) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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just starting with boost
by Fred J. 24 Jul '06

24 Jul '06

Hi I installed boost on my debian testing and read some examples and docs., however I failed to find some example on how one can read a data file in a matrix in-order to do some coloum arithmatics. any pointers will be appriciated. thanks --------------------------------- See the all-new, redesigned Yahoo.com. Check it out.

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Re: [Boost-users] [multi_index] - duplicates_iterator.hpp issue?
by JOAQUIN LOPEZ MU?Z 23 Jul '06

23 Jul '06

Bogdan M. ha escrito: > > Hi, > > I am trying to serialize a multi-indexed container defined as > below ( I am using boost 1.33.1 ): [...] > > While serializing this container containing ===> several nodes > with the same key <===, I get an access violation exception > somewhere deep in the multi_index library. > Tracing a little bit back the stack I noticed something unusual in > boost_1_33_1\install\include\boost\multi_index\detail\ > duplicates_iterator.hpp > in the duplicates_iterator::sync() member function (around line 80): > > void sync() > { > if(pred(begin_chunk->value,node->value))advance(); > } > > This function seems to advance the iterator within a chunk of equal > keys. However, the if clause does not consider the case where > node == end. These are exactly the circumstances under which my > program crashes in 'pred(begin_chunk...)'. > Changing the if condition into > > void sync() > { > if( (node != end) && pred(begin_chunk->value,node->value)) > advance(); > } > > seems to fix the problem. However, I am not familiar with the > overall implementation and therefore I cannot tell whether this > is indeed the cause or whether there are side-effects > to my patch. > Has anyone else experienced a situation similar to this one? Hello Bogdan, You have certainly spotted a bug in duplicates_iterator.hpp, and the fix you propose is correct. As it happens, this was first reported some months ago: http://lists.boost.org/boost-users/2006/01/16710.php and the bug was fixed since then in the CVS, in what will become Boost 1.34. Until that release comes out, your local fix is perfect. Anyway, in case you can afford it, I recommend you switch now to the CVS version, as it contains a few other bugfixes. > Is there something wrong with my container definition, to > begin with? I don't see anything wrong with your container definition. > I really appreciate any feedback. > Thanks, > Bogdan Thank you for using Boost.MultiIndex, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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serialization on const member and map<const CLASS*, CLASS>
by Cheok Yan Cheng 23 Jul '06

23 Jul '06

Hi, I am trying to perform serialization on a const member const ImageRegion* imageRegion; By refering to http://www.boost.org/libs/serialization/doc/serialization.html#const, I thought the following code would work. friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & const_cast<ImageRegion *>(imageRegion); } However, I still get the following error is VC++ 2003 c:\yccheok\pcbvisionlib\FiducialPair.h(42): error C2679: binary '&' : no operator found which takes a right-hand operand of type 'ImageRegion *' (or there is no acceptable conversion) I had fully tested the ImageRegion class. Before this const member variable, it can be fully serialized with no problem. Any suggestion? Thank you! p/s By refering to the mailing list "(de)serializing vector<const A*>" http://groups.google.com/group/boost-list/browse_frm/thread/79dba906901d039…, does it mean that boost is also not allow to (de)serialize map<const CLASS*, CLASS> directly? Must I iterate through the map elements one by one to serialize them manually? __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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[multi_index] - duplicates_iterator.hpp issue?
by Bogdan M. 23 Jul '06

23 Jul '06

Hi, I am trying to serialize a multi-indexed container defined as below ( I am using boost 1.33.1 ): ____________________________________________________________________________ ___ /** Shorter id of namespaces. */ namespace bmi = boost::multi_index; /** Tags for accessing several indices defined below */ struct name_tag {}; class string_node { public: std::string m_name; friend class boost::serialization::access; void serialize ( boost::archive::polymorphic_iarchive & ar, const unsigned int file_version); void serialize ( boost::archive::polymorphic_oarchive & ar, const unsigned int file_version); }; /** Container of children of a node in the string tree */ typedef boost::multi_index_container< string_node*, bmi::indexed_by< bmi::sequenced<>, // sequenced type bmi::ordered_non_unique< bmi::tag<name_tag>, BOOST_MULTI_INDEX_MEMBER( string_node, const std::string, m_name)> > > node_set; ____________________________________________________________________________ ___ While serializing this container containing ===> several nodes with the same key <===, I get an access violation exception somewhere deep in the multi_index library. Tracing a little bit back the stack I noticed something unusual in boost_1_33_1\install\include\boost\multi_index\detail\duplicates_iterator.hp p in the duplicates_iterator::sync() member function (around line 80): ____________________________________________________________________________ ___ void sync() { if(pred(begin_chunk->value,node->value))advance(); } ____________________________________________________________________________ ___ This function seems to advance the iterator within a chunk of equal keys. However, the if clause does not consider the case where node == end. These are exactly the circumstances under which my program crashes in 'pred(begin_chunk...)'. Changing the if condition into ____________________________________________________________________________ ___ void sync() { if( (node != end) && pred(begin_chunk->value,node->value)) advance(); } ____________________________________________________________________________ ___ seems to fix the problem. However, I am not familiar with the overall implementation and therefore I cannot tell whether this is indeed the cause or whether there are side-effects to my patch. Has anyone else experienced a situation similar to this one? Is there something wrong with my container definition, to begin with? I really appreciate any feedback. Thanks, Bogdan

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Re: [Boost-users] [Serialization] Problem serializing via baseclassptr
by Guy Létourneau 22 Jul '06

22 Jul '06

Robert, I've created a simple test as you suggested. The problem is that the test does not even build (in oserializer.hpp, there are 2 conditions for this to happen but none seems to match my test..). Here's what the compiler gives me: C:/Boost/include/boost-1_33_1/boost/archive/detail/oserializer.hpp: In function `void boost::archive::save(Archive&, T&) [with Archive = boost::archive::text_oarchive, T = A]': C:/Boost/include/boost-1_33_1/boost/archive/basic_text_oarchive.hpp:78: instantiated from `void boost::archive::basic_text_oarchive<Archive>::save_override(T&, int) [with T = A, Archive = boost::archive::text_oarchive]' C:/Boost/include/boost-1_33_1/boost/archive/detail/interface_oarchive.hpp:78: instantiated from `Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = A, Archive = boost::archive::text_oarchive]' ../main.cpp:90: instantiated from here C:/Boost/include/boost-1_33_1/boost/archive/detail/oserializer.hpp:567: error: incomplete type `boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value' #include <iostream> #include <fstream> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> class A { public: A() { i = 1; }; virtual ~A() { }; virtual void Dummy() = 0; private: int i; }; BOOST_IS_ABSTRACT(A) class B : public A { public: B() { }; virtual ~B() { }; void Dummy() { }; void SetValue( std::string& value ) { Data = value; } private: friend class boost::serialization::access; template <class Archive> void serialize( Archive& ar, const unsigned int version ) { ar & boost::serialization::base_object<A>( *this ); ar& Data; std::cout << "Serialization of B" << std::endl; std::cout.flush(); } std::string Data; }; BOOST_CLASS_EXPORT(B); int main() { // Create a B object B* Child = new B; // Set some data std::string Data = "test"; Child->SetValue( Data ); // Assign it to a A ptr A* Parent = Child; // create and open a character archive for output std::ofstream ofs( "filename" ); // save data to archive { try { boost::archive::text_oarchive oa( ofs ); // write class instance to archive oa << *Parent; } catch( boost::archive::archive_exception& e ) { std::cout << "Save failed! : " << e.what(); std::cout.flush(); return false; } catch( ... ) { std::cerr << "Unknown Exception " << std::endl; return false; } // archive and stream closed when destructors are called } delete Child; } The example is very simple. Again, I have problems only when serializing via a base class ptr (serializing object "directly" works fine). Thanks again for your help, Guy >Hmm - looks like it should work to me. > >I would try the following: > >a) make a tiny test - a main which which does nothing but tests the >serialization. >This you can ship to us in necessary. >b) For now - remove all the BOOST_CLASS_TRACKING macros. >It shouldn't make a difference but let's start simple. >c) You'll have to add BOOST_CLASS_EXPORT for SomeData >d) double check that everything is in the same namespace. >e) try removing the friend class boost::serialization::access; from >the base class. NonVolatileData::serialize(..) should never be called >by the serialization library in this case - so if this traps during >compile, >it will show a chain of "compile time calls". By looking at this chain >one can see where things went wrong. Unfortunately this requires >looking at the header source code - oh well. >f) double check that the test corresponding to your example builds >and runs in your environment. If that passes, but yours does not, try >modifying the test bit by bit by commenting out the code that is there >and replacing it with your own code. If you finish this and the test >still works - then just remove all the commented code and you'll be >done. > >Robert Ramey Guy Létourneau wrote: > Robert, > I've tried to include your changes but it doesn't solve the problem. > I had to add the following line: BOOST_IS_ABSTRACT(NonVolatileData) > for the program to compile. I agree with you, to have an abstract > class is what is needed in that case as the NonVolatileData class is > not intended to do something useful except for allowing my data > storage layer to be generic. However, abstract or not, I still have > the same problem: when serializing my SomeData object through a > pointer to the NonVolatileData, only the data of the parent class > gets serialized. Anything else you want me to try? > > Thanks, > Guy > >> Try making the base class polymorphic - that it define at least >> one abstract function. See my changes below. This will have >> the beneficial effect of inhibiting anyone from creating an instance >> of your base class directly. >> Robert Ramey > >> Guy Létourneau wrote: >>> Hello, >>> >>> I need to develop a generic data storage layer. Its job is to handle >>> the serialization of all objects that need to be persistent in my >>> system and handle management of archives, backups and restores and >>> so forth. The most important point is that it must stay generic, >>> i.e. have no knowledge of the type of objects being passed by other >>> modules in the system. Because of this, I define a base class >>> NonVolatileData from which all data classes in the system will >>> derive: >>> >>> /////////////////////////////////////////////////////////////////////// >>> // Base class >>> class NonVolatileData >>> { >>> friend >>> class boost::serialization::access; >>> >>> public: >>> >>> NonVolatileData(){ i = 1; }; >>> virtual ~NonVolatileData() = 0; // Note - pure virtual function >>> make class abstract- >>> >>> >>> protected: >>> >>> virtual void Dummy() =0; // Note - pure virtual function make >>> class abstract- >> ; >>> >>> int i; >>> template <class Archive> >>> void serialize( Archive& ar, const unsigned int version ) >>> { >>> ar & i; >>> } >>> }; >>> BOOST_CLASS_TRACKING(NonVolatileData, >>> boost::serialization::track_never) >>> >>> >>> class SomeData: public NonVolatileData >>> { >>> friend >>> class boost::serialization::access; >>> >>> public: >>> >>> SomeData () >>> { >>> }; >>> >>> ~SomeData () >>> { >>> }; >>> >>> void SetValue( std::string& Address ) >>> { >>> this->Address = Address; >>> } >>> >>> void Dummy() >>> { >>> } >>> >>> private: >>> >>> template <class Archive> >>> void serialize( Archive& ar, const unsigned int version ) >>> { >>> ar & >>> >>> boost::serialization::base_object<NonVolatileData>(*this); >>> ar& Address; } >>> >>> std::string Address; >>> }; >>> BOOST_CLASS_TRACKING(SomeData, boost::serialization::track_never) >>> ///////////////////////////////////////////////////////////////// >>> >>> My data storage interface will take a ptr to the base class i.e. >>> Save(NonVolatileData* data) so the serialization will be performed >>> through a ptr to the base class. I've read the documentation >>> multiple times and I'm still unable to make that work correctly. >>> When a do a save, only the base class is serialized even though the >>> base class is polymorphic. I've tried using the >>> BOOST_CLASS_EXPORT_GUID macro the force a registration of my derived >>> class without success. I've also checked the example from demo.cpp. >>> It uses the direct call to register_type() but in my case, I don't >>> want to change the code everytime a new class is defined in the >>> system so I went with option 2 (the macro). There's probably a >>> subtle detail I do not do correctly (polite way of saying I'm >>> missing something :-)). >>> >>> Thanks for your help, >>> >>> Guy Letourneau =

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[serialization] Skipping unexpected elements in XML archive
by Todd Greer 22 Jul '06

22 Jul '06

Hi, I'm using the Serialization library, but need to skip unrecognized data when reading in an archive. This is for forward compatability purposes; I need for older versions of my software to consume files produced by newer ones, which may have added elements. As this functionality is not currently in the library, I have created a new archive type (as I think Robert Ramey suggested at some point). It inherits from xml_iarchive_impl and overrides load_override to identify when it has just read an opening tag with an unexpected name. It then skips whatever XML it finds within the unexpected element, reads the closing tag, and returns to normal processing. I use it with the unaltered xml_oarchive, and the pair satisfy my requirements. I'm including it below in the hopes that someone will find it useful. I've tested it on MSVC 7.1 (Visual Studio .NET 2003) with a reasonably complex XML file with both nested and non-nested unexpected elements. If you'd like, I can post some tests as well (I just need to strip out some project-specific details). Please let me know if you see any places where it could be improved, or where I've completely missed something; this is my first use of the serialization library, and my understanding is far from comprehensive. Many thanks to all who've contributed to the Serialization library, Todd Greer <tgreer <at> affinegy dot com> Senior Software Developer, Affinegy LLC #include <boost/archive/xml_iarchive.hpp> #include <boost/range/end.hpp> #include <algorithm> const char whitespace[] = " \t\n\r"; //Skip whitespace, then return true if we're looking at '</'. //Leave the stream right before the '<'. template<class IStream> bool at_close_tag(IStream& is) { char ch; using boost::end; do { ch = is.get(); } while(std::find(whitespace, end(whitespace), ch) != end(whitespace)); assert(ch == '<'); ch = is.get(); bool const end_tag = ch == '/'; is.putback(ch); is.putback('<'); return end_tag; } template<class Archive> class skip_xml_iarchive_impl: public boost::archive::xml_iarchive_impl<Archive> { #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) //see xml_iarchive_impl public: #elif defined(BOOST_MSVC) friend boost::archive::detail::interface_iarchive<Archive>; protected: #else friend class boost::archive::detail::interface_iarchive<Archive>; protected: #endif skip_xml_iarchive_impl(std::istream & is, unsigned int flags = 0): xml_iarchive_impl<Archive>(is, flags) {} void skip_all_elements() { std::string ignore; if(this->This()->gimpl->parse_string(this->This()->get_is(), ignore) && ignore.npos != ignore.find_first_not_of(whitespace)) return; //We're either looking at a start tag or an end tag. while(!at_close_tag(this->This()->get_is())) {//It's a start tag. if(!this->This()->gimpl->parse_start_tag(this->This()->get_is())) boost::throw_exception(archive_exception(archive_exception::stream_error )); ++depth; std::string const name = this->This()->gimpl->rv.object_name; skip_all_elements(); load_end(name.c_str()); } } template<class T> void load_override( #ifndef BOOST_NO_FUNCTION_TEMPLATE_ORDERING const #endif boost::serialization::nvp<T> & t, int ){ if(!t.name()) return xml_iarchive_impl<Archive>::load_override(t, 0); load_start(t.name()); // don't check start tag at highest level const std::string name_found = this->This()->gimpl->rv.object_name; bool const skip = depth > 1 && 0 != (this->get_flags() & no_xml_tag_checking) && name_found != t.name(); if(skip) skip_all_elements(); else boost::archive::load(* this->This(), t.value()); load_end(skip ? name_found.c_str() : t.name()); if(skip) //We still haven't loaded t... load_override(t, 0); //...so load t. } template<class T> void load_override(T & t, BOOST_PFTO int i) { xml_iarchive_impl<Archive>::load_override(t, i); } }; class skip_xml_iarchive: public skip_xml_iarchive_impl<skip_xml_iarchive> { public: skip_xml_iarchive(std::istream & is, unsigned int flags = 0) : skip_xml_iarchive_impl<skip_xml_iarchive>(is, flags) {} }; -- Todd Greer <tgreer <at> affinegy dot com> Senior Software Developer, Affinegy LLC

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bjam crashes when building Boost on Windows
by Adam Wright 22 Jul '06

22 Jul '06

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi all, When trying to build boost 1.33.1 this afternoon, I encountered a problem with bjam just crashing every time I invoked it when targeting Windows. I've debugged the problem as being files with dates < 1900 in directories being searched by the glob expansions (I had a rogue file from 1757 in C:\Windows\). file_dirscan in filent.c invokes the MSCRT function _tfindnext64i32, which will eventually assert if the date is too far back in time. It's a documented limitation of the function, so my suggestion would be to FAQ this "bug" for the (very few) people it's likely to bite. Thanks, adamw -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.3 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEwlW/9mihfAI44D0RAtyDAJ46wfH9UBhsz58nNTtKTyftI0l1igCghVD1 s18ec8+vbIevjIskC40W9Rc= =i7Ap -----END PGP SIGNATURE-----

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