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[serialization] a proposal for an alternative to the new const-saving rule
by Joaquín Mª López Muñoz 27 Jun '05

27 Jun '05

Hello, The new rule introduced in Boost.Serialization that forbids saving of non-const objects has proved a little controversial. My point of view is that the rule, albeit far from perfect, provides some level of safety against hard to track errors. Others' opinions differ. The current rule is a rough approximation to what IMHO would constitute the right enforcement: everytime a trackable object is saved, check wether an object with the same address has been previously saved and, if so, make sure that the object didn't change. The hardest part is checking for equality. My proposal is to follow a hash-based approach, which is effective both in terms of complexity and space (one word per tracked object.), and does not impose any special requirement on the serialized objects (for instance, an approach based on operator== would require that objects be equalitycomparable). How does one compute a hash value for an object being saved? It is easy to do recursively as follows (pseudocode): unsigned int* hash_addr=0; // a member of the current archive internal_save(object obj) { if(hash_addr!=0 || obj is trackable) { // a hash computation is in course or we need to initiate one unsigned int* old_hash_addr=hash_addr; unsigned int h=0; hash_addr=&h; user_defined_save(o); set_hash(o,h); hash_addr=old_hash_addr; if(hash_addr!=0){ // add h to the hash being computed boost::hash_combine(*hash_addr,h); } } else{ user_defined_save(o); } } user_defined_save(primitive_type x) // provided by Boost.Serialization { if(hash_addr!=0){ boost::hash_combine(*hash_addr,x); } // rest of serialization stuff, as always } This implementation does not impose any additional requirement on the objects being serialized and is totally transparent to the user (she doesn't have to do any hash-related work herself.) With the computed hash values, Boost.Serialization can emmit run-time errors if a trackable object is serialized twice and changed in between (currently, the errors are compile-time.) What do you think? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Re: [boost] [serialization] a proposal for an alternative to thenewconst-saving rule
by JOAQUIN LOPEZ MU?Z 27 Jun '05

27 Jun '05

----- Mensaje original ----- De: David Abrahams <dave(a)boost-consulting.com> Fecha: Sábado, Junio 25, 2005 1:39 am Asunto: Re: [boost] [serialization] a proposal for an alternative to thenewconst-saving rule > "JOAQUIN LOPEZ MU?Z" <joaquin(a)tid.es> writes: > > > > De: David Abrahams <dave(a)boost-consulting.com> > > >> But all of this misses the high-level problem: the author of > the code > >> doesn't know what he's doing. You simply can't serialize > objects from > >> distinct scopes with tracking into the same archive, because > there may > >> be aliasing. > > > > Totally agreed, this is what we are trying to detect > > in order to protect the author of the code. > > > >> And there's nothing we can reasonably do to detect that > >> problem when the aliased objects have the same type > > > > Nothing? I'm afraid I don't get you. A perfect > > aliasing detection mechanism is probably impossible > > to implement, but the hash test at least approximates it. > > This is better than providing no safety mechanism, > > as I understand you advocate. > > I'm not sure it is. There's an imposition on users: all the types > they want to serialize have to support hashing. No, no. Please check the piece of pseudocode on my first message: the hash code is automatically built by Boost.Serialization, without any intervention from the user, and certainly without any requirement that the type be hashable (in the sense of providing a hash_value overload or something like this.) Let me illustrate with an example: struct labelled_point { int x; int y; string label; template <class Archive> void serialize(Archive & ar, const unsigned int version) { ar & x; ar & y; ar & label; } }; struct labelled_segment { labelled_point p0,p1; template <class Archive> void serialize(Archive & ar, const unsigned int version) { ar & p0; ar & p1; } }; So, given an object seg of type labelled_line, the framework automatically constructs the following associated hash value: combine( combine( boost::hash<int>(seg.p0.x), boost::hash<int>(seg.p0.y), boost::hash<std::string>(seg.p0.label)), combine( boost::hash<int>(seg.p1.x), boost::hash<int>(seg.p1.y), boost::hash<std::string>(seg.p1.label))) (combine(...) is shorthand for the obvious combination formula of hash values using boost::hash_combine.) The process recursively goes down to primitive types, as specified in my proposed pseudocode, and only these have to be hashable, but fortunately they are. > > It is nice that the serialization library automatically takes care of > hashing aggregated types and leaving out the unserialized data... > > uh, wait: this will never work unless you plan only to do shallow > hashing. Otherwise you will get an exponential explosion for some > object graphs. Is that your intention? I'm not getting you. The hash value is calculated as part of the saving process itself, so it has the very same complexity. I've got the hunch you might be meaning something else, could you please elaborate? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[Boost-bugs] [ boost-Support Requests-1228143 ] Grep() hangs for a particular string
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228143, was opened at 2005-06-27 10:26 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228143&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Grep() hangs for a particular string Initial Comment: We have the following code. std::vector<std::string> v; boost::RegEx expr(strSearchValue, TRUE); expr.Grep(v, strObjectValue); Statement expr.Grep(v, strObjectValue); hangs when expr is "(?=stl)" and strObjectValue is Example (M- STL) Could somebody tell me why are we hanging doing Grep ()? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228143&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Support Requests-1228130 ] Grep() hangs for a particular string
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228130, was opened at 2005-06-27 10:04 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228130&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Grep() hangs for a particular string Initial Comment: We have the following code. std::vector<std::string> v; boost::RegEx expr(strSearchValue, TRUE); expr.Grep(v, strObjectValue); Statement expr.Grep(v, strObjectValue); hangs when expr is "(?=stl)" and strObjectValue is Example (M- STL) Could somebody tell me why are we hanging doing Grep ()? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228130&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Support Requests-1228128 ] Linker Error : File 'boost_regex_vc7_mdid.lib' not found.
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228128, was opened at 2005-06-27 09:59 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228128&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Linker Error : File 'boost_regex_vc7_mdid.lib' not found. Initial Comment: We opened a VC6 project, that uses Boost libraries, in VS .Net 2003. It compiles properly, but fails to link. The error is fatal error LNK1104: cannot open file 'boost_regex_vc7_mdid.lib'. Does anybody have an idea how we can get this file? plus we would like to know how to set the STLport_path? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228128&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Support Requests-1228122 ] Linker Error : File 'boost_regex_vc7_mdid.lib' not found.
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228122, was opened at 2005-06-27 09:47 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228122&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Linker Error : File 'boost_regex_vc7_mdid.lib' not found. Initial Comment: We opened a VC6 project, that uses Boost libraries, in VS .Net 2003. It compiles properly, but fails to link. The error is fatal error LNK1104: cannot open file 'boost_regex_vc7_mdid.lib'. Does anybody have an idea how we can get this file? plus we would like to know how to set the STLport_path? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228122&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Support Requests-1228108 ] Linker Error : File 'boost_regex_vc7_mdid.lib' not found.
by SourceForge.net 27 Jun '05

27 Jun '05

Support Requests item #1228108, was opened at 2005-06-27 09:22 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228108&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: NPrasad (prasadrn) Assigned to: Nobody/Anonymous (nobody) Summary: Linker Error : File 'boost_regex_vc7_mdid.lib' not found. Initial Comment: We opened a VC6 project, that uses Boost libraries, in VS .Net 2003. It compiles properly, but fails to link. The error is fatal error LNK1104: cannot open file 'boost_regex_vc7_mdid.lib'. Does anybody have an idea how we can get this file? plus we would like to know how to set the STLport_path? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1228108&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[serialization][tru64cxx65] access problem and DR45
by JOAQUIN LOPEZ MU?Z 27 Jun '05

27 Jun '05

Hello, With the recent change to strict_ansi mode, Compaq C++ compiler is stumping into some problems. Currently, Boost.Serialization fails to build because of the following: http://tinyurl.com/7cacb This is a reduced form of the layout the compiler is having a hard time with (in boost/archive/impl/basic_xml_grammar.hpp): template<class CharType> class basic_xml_grammar { private: typedef std::basic_string<CharType> StringType; public: struct return_values { StringType object_name; }; }; The compiler complains that StringType, as used in the definition of object_name, is inaccesible. I'm no C++ guru, but I understand the construct is legal according to DR45. What puzzles me is that Compaq C++ is seemingly the only compiler failing on this, when the DR45 was approved well after the standard (in 2001, I think.) Anyway, I propose to make basic_xml_grammar::StringType public, as it can really do no harm and Compaq C++ will welcome it. Any objection? Do I commit the change? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[Boost-bugs] [ boost-Bugs-1228050 ] Problem with mpl::transform on fusion::tuple
by SourceForge.net 27 Jun '05

27 Jun '05

Bugs item #1228050, was opened at 2005-06-27 01:47 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1228050&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: mpl Group: None Status: Open Resolution: None Priority: 5 Submitted By: SolodOn (solodon) Assigned to: Aleksey Gurtovoy (agurtovoy) Summary: Problem with mpl::transform on fusion::tuple Initial Comment: Whenever I try to do something like: typedef fusion::tuple<char, short, int> fusion_types; typedef fusion::tuple<char*,short*,int*> fusion_pointers; typedef mpl::transform< fusion_types, boost::add_pointer<mpl::_1> >::type fusion_result; I get a compilation error, while the same thing with mpl::vector instead of fusion::tuple compiles perfectly well. If I understand the problem right, dispatched implementation of push_front on tuples refers boost::fusion::meta::push_front, which is forward declared but never defined. Is it by design or was it left to add implementation later? Another thing you might want to check (not directly related to this) is that tuple iterator does not define iterator category, that was required by some mpl algorithms. I've got here GCC 3.4 (under Linux FC3) and boost 1.32 taken from boost CVS. See attachment for the program to reproduce the problem (uncomment two last lines) and compilation log. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1228050&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[serialization] new STATIC_ASSERTION_FAILURE
by Vladimir Prus 27 Jun '05

27 Jun '05

I've just updated my Boost tree, and now get this: /space/NM/boost/boost/serialization/type_info_implementation.hpp:48: error: incomplete type `boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value' The check in type_info_implementation.hpp was introduced in revision 1.4 of that file. I should also note that log message is "invoke auto-link only when necessary", which is clearly not accurate, given that the STATIC_ASSERT does not have anything to do with auto-linking. There's no comment why the STATIC_ASSERTION is there. So, what's that? If I add #include <boost/serialization/extended_type_info_typeid_fwd.hpp> to the top of the file (to grab definition of BOOST_SERIALIZATION_DEFAULT_TYPE_INFO), things start to look better, but I get: /space/NM/boost/boost/archive/detail/iserializer.hpp:113: error: incomplete type 'boost::serialization::extended_type_info_typeid<const boost::scoped_ptr<lvk::nm_model::runtime::BlockFormula::data> >' cannot be used to name a scope When I change the include to be: #include <boost/serialization/extended_type_info_typeid.hpp> I get this: /space/NM/boost/boost/archive/basic_archive.hpp:21:2: #error "no serialization headers my precede anyarchive headers" I don't understand this error. What if I have a header file MyClass.hpp that declares a serialize function. So, I might need to include <serialization/base_object.hpp>. I need to do that in the header, I believe. Now if I include archive headers in a .cpp file, will that trigger an error? Or the above rule has some exceptions? Ok, now to base_object.hpp. I get: /space/NM/boost/boost/serialization/base_object.hpp:75: error: parse error before `;' token because the header uses 'type_info_implementation' without including the appropriate header. So, to summarize: 1. Could the type_info_implementation.hpp header be fixed either by including #include <boost/serialization/extended_type_info_typeid.hpp> or in some other way. 2. Could base_object.hpp be fixed either by including the appropriate header, or in some other way. 3. What are the exact rules about relative order of serialization/ and archive/ includes? - Volodya

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