March 2006 - Boost-users - lists.boost.org

Re: [Boost-users] SOLVED! Re: multi_index 1.33.0, known problems with RHEL 3 compiler (gcc 3.2.3)?
by JOAQUIN LOPEZ MU?Z 13 Mar '06

13 Mar '06

Hi Bert, ----- Mensaje original ----- De: bert hubert <bert.hubert(a)netherlabs.nl> Fecha: Domingo, Marzo 12, 2006 11:31 am Asunto: [Boost-users] SOLVED! Re: multi_index 1.33.0,known problems with RHEL 3 compiler (gcc 3.2.3)? > On Sat, Mar 11, 2006 at 10:03:21PM +0100, JOAQUIN_LOPEZ_MU?Z wrote: > > 2. You might try the equivalent expression: > > > > waiters_by_ttd_index_t& ttdindex= > > boost::multi_index::get<KeyTag>(d_waiters); > > Indeed, that solved the problem! I think what confused the older > 'weaker'gcc is that all this code is within a template class. > Thank you Joaquin! See > http://mailman.powerdns.com/pipermail/pdns-users/2006- > March/003140.html [...] Good! Thanks for using Boost.MultiIndex, hope you're enjoying it. > > Another question, I now have this: > struct CacheEntry > { > CacheEntry(const string& name, const vector<StoredRecord>& > records) : d_name(name), d_records(records) > {} > string d_name; > typedef vector<StoredRecord> records_t; > records_t d_records; > uint32_t getTTD() const > { > uint32_t earliest=numeric_limits<uint32_t>::max(); > for(records_t::const_iterator i=d_records.begin(); i != > d_records.end(); ++i) > earliest=min(earliest, i->d_ttd); > return earliest; > } > }; > > typedef multi_index_container< > CacheEntry, > indexed_by < > > hashed_unique<member<CacheEntry,string,&CacheEntry::d_name> >, > > ordered_non_unique<const_mem_fun<CacheEntry,uint32_t,&CacheEntry::getTT D> > > > > > cache_t; > > I then fill up a cache_t object, but I find that pruning it takes > O(n^2)time based on how many entries I prune in one go. I'm now > pruning once every > 10 seconds, which takes 10 to 20ms per try, if I prune once every > 3 minutes, > pruning takes 10 seconds! > > The odd thing is that it appears to matter how much you prune in > one go, > without inserting something in the container in between. Perhaps > the cost is > amortized? > > The pruning code: [...] So, the prunning code goes like: /* 1 */ for(j=ttdindex.begin();j!=ttdindex.end();){ // leave to-be-pruned elements at the beginning // of ttdindex } /* 2 */ ttdindex.erase(ttdindex.begin(), j); So as to make sure, where do you observe the O(n^2) behavior, /* 1 */ or /* 2 */ (or both) ? Can you time both parts separately? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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"Re: serialization : XML Schema?"
by m.korbosli 13 Mar '06

13 Mar '06

Jeff Flinn wrote: >Wouldn't this be best described by the Spirit grammar definition used >by xml_iarchive? I would be grateful if you give me a link or a file in which I can find more details about that. Accédez au courrier électronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,34 /mn) ; tél : 08 92 68 13 50 (0,34/mn)

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Build a Universal Binary Boost library for Mac OSX
by Jwahar Bammi 13 Mar '06

13 Mar '06

Will appreciate a clear recipe to build Universal Binary boost libraries for Mac OSX (darwin). Boost is so wonderful, cant say the same for bjam ,,,,,,, Google'ing only pointed to the adobe patch I tried the adobe patch. Patched boost_1_33_1/tools/build/v2/tools/ darwin.jam then issued bjam -sarch=fat -sARCH=fat -sTOOLS=darwin stage (then install) did not make universal .dylibs. I suspect its got something to do with v1 vs v2 bjam or some such, i am just not grokking it. Will appreciate a ccokbook style recipe (have no particular desire to learn bjam) thanks bammi AT memento-inc DOT com

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lambda and typeof, finally an effective in-place arithmetic metafunction generator.
by pongba 13 Mar '06

13 Mar '06

Okay, just image some sort of code like this: typedef mpl::vector_c<int,1,2,3> v; typedef mpl::accumulate<v,int_<0>,MPL_METAFUNC(_1*CONS(10)+_2)>::type::value result_value; // =123 Imaginably, the implementation of MPL_METAFUNC would involve BOOST_TYPEOF to deduce the type of "_1*CONS(10)+_2" so as to construct a corresponding metafunction, that is, "mpl::plus<_2,mpl::times<_1,int_<10> > >" (CONS here is used to work around the embarrassment that 10 becomes sort of variable when passed directly to operator*, so we use CONS(10) which expands into something like "int_<10>()" which entirely preserve "10" at compile-time). Arguably this is feasible, but I lack the time to implement it fully. (although it would be pretty simple, e.g. #define DEFINE_BINARY_OP(op,mpl_binray_op) \ template <typename T, typename U> \ mpl_binary_op<T,U> operator op (T t, U u) \ { \ return mpl_binary_op<T,U>(); \ } \ DEFINE_OP(+,mpl::plus) DEFINE_OP(-,mpl::minus) DEFINE_OP(*,mpl::times) DEFINE_OP(/,mpl::divide) ... Admittedly, there exists a name confliction between mpl::_1 and lambda::_1 due to the inherent difference between type and variable in the language, so we couldn't use the same _1 and _2 in both "plus<_1,_2>" and "_1+_2". Any good remedies for that?(of course we could always turn to "_1()+_2()" in which _1/2 means mpl::_1/2) My question is: Is this valuable?(IMO,it'll make arithmetic operation in metaprogramming much easier and clearer, just watch "_1*10+_2" v.s. "mpl::plus<_2,mpl::times<_1,int_<10> > >" you'll see that). And if it is, would Dave consider adding it to MPL? Thanks in advance! -- Regards!

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serialization : XML Schema?
by m.korbosli 13 Mar '06

13 Mar '06

Hi, I 'm working on a project where I want to parse XML archives generated by boost serialization library, except that I didn't find any serialization's specification or XML schema describing this mechanism. Is there any documentation providing this? Thanks Accédez au courrier électronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,34 /mn) ; tél : 08 92 68 13 50 (0,34/mn)

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"Re: serialization : XML Schema?"
by m.korbosli 13 Mar '06

13 Mar '06

Vladimir Prus wrote: >>Was the original question about schema for specific serialized data >>types,or rather for general syntax of XML archives, regardless >>of the serialized types? It sounded like the latter for me. Yes, it's about the latter! I'm seeking a general syntax in order to verify the coherence of the serialized data when parsing XML archives. Is there anything about that? Thanks Accédez au courrier électronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,34 /mn) ; tél : 08 92 68 13 50 (0,34/mn)

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BGL Graph - Edge_connectivity
by Adam Hartshorne 13 Mar '06

13 Mar '06

Hi All, What does the edge_connectivity function do? I can't find any reference to it in the online documentation. Adam

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boost::serialization doesn't support iterators?
by 'Carlo Wood' 13 Mar '06

13 Mar '06

I looked for hours in the docs, because I couldn't believe that a serialization library that supports deep copying of pointers and STL containers wouldn't even MENTION iterators (after all, iterators are the pointers of the STL). However, it seems that boost::serialization simply does not support serializing iterators! Is this true? I really need to serialize iterators, how can I do that? -- Carlo Wood <carlo(a)alinoe.com>

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Syntax of get for Variant and any_cast for Any
by Scott Meyers 13 Mar '06

13 Mar '06

It took me a little while to figure out that get<T> on a variant is really just the moral equivalent of dynamic_cast<T> with a funny syntax. I'd like to understand why, given a variant v, this syntax is used T* p = get<T>(&v); T& r = get<T>(v); instead of this: T* p = variant_cast<T*>(&v); T& r = variant_cast<T&>(v); any_cast on pointers also uses what I consider to be a counterintuitive syntax, using this (for an any object a) T* p = any_cast<T>(&a) instead of this: T* p = any_cast<T*>(&a) However, any_cast to a reference works with a syntax analogous to dynamic_cast. Implementing the "expected" syntax doesn't seem to be too difficult. For example, here's my quick cut at variant_cast: template<typename T, typename U1, typename U2, typename U3> T variant_cast(boost::variant<U1, U2, U3>& v) // ref { using namespace boost; BOOST_STATIC_ASSERT(is_reference<T>::value); return get<remove_reference<T>::type>(v); } template<typename T, typename U1, typename U2, typename U3> T variant_cast(const boost::variant<U1, U2, U3>& v) //ref-to-const { using namespace boost; BOOST_STATIC_ASSERT(is_reference<T>::value); return get<remove_reference<T>::type>(v); } template<typename T, typename U1, typename U2, typename U3> T variant_cast(boost::variant<U1, U2, U3> *pv) // ptr { using namespace boost; BOOST_STATIC_ASSERT(is_pointer<T>::value); return get<remove_pointer<T>::type>(pv); } template<typename T, typename U1, typename U2, typename U3> T variant_cast(const boost::variant<U1, U2, U3> *pv) // ptr-to-const { using namespace boost; BOOST_STATIC_ASSERT(is_pointer<T>::value); return get<remove_pointer<T>::type>(pv); } In a thread last month, Marc Mutz posted this approach to "normalizing" the syntax of any_cast: template <typename T> class any_cast2 : noncopyable { const any & m_any; public: explicit any_cast2( const any & v ) : m_any( v ) {} operator T() const { return any_cast<T>( m_any ); } }; template <typename T> class any_cast2<T*> : noncopyable { any * const m_any; public: explicit any_cast2( any * v ) : m_any( v ) {} operator T * () const { return any_cast<T>( m_any ); } }; template <typename T> class any_cast2<const T*> : noncopyable { const any * const m_any; public: explicit any_cast2( const any * v ) : m_any( v ) {} operator const T * () const { return any_cast<T>( m_any ); } }; template <typename T> class any_cast2<T&> : noncopyable { any & m_any; public: explicit any_cast2( any & v ) : m_any( v ) {} operator T & () const { return any_cast<T&>( m_any ); } }; template <typename T> class any_cast2<const T&> : noncopyable { const any & m_any; public: explicit any_cast2( const any & v ) : m_any( v ) {} operator const T & () const { return any_cast<const T&>( m_any ); } }; Maybe there are problems to these approaches -- I've hardly investigated them. But I would be interested to know if there is a good reason for the syntaxes for dynamic_cast, any_cast, and get to vary so much. Thanks, Scott

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boost::serialization Bug
by Carlo Wood 13 Mar '06

13 Mar '06

Ok, it's not a "bug"... but it's damn annoying to get compiler warnings from library header. Especially when those compiler warnings are 1 page long. Is it possible to please not mention variables that aren't being used? This is what I get for a SINGLE warning: /usr/include/boost/archive/detail/interface_oarchive.hpp: In instantiation of ‘const boost::archive::detail::basic_pointer_oserializer* boost::archive::detail::interface_oarchive<Archive>::register_type(T*) [with T = std::set<DirTree, std::less<DirTree>, std::allocator<DirTree> >, Archive = boost::archive::xml_oarchive]’: /usr/include/boost/archive/detail/oserializer.hpp:332: instantiated from ‘static const boost::archive::detail::basic_pointer_oserializer* boost:: archive::detail::save_pointer_type<Archive, TPtr>::non_abstract<T>:: register_type(Archive&) [with T = std::set<DirTree, std::less<DirTree>, std::allocator<DirTree> >, Archive = boost::archive::xml_oarchive, TPtr = DirTrees*]’ /usr/include/boost/archive/detail/oserializer.hpp:349: instantiated from ‘static const boost::archive::detail::basic_pointer_oserializer* boost:: archive::detail::save_pointer_type<Archive, TPtr>::register_type(Archive&, T&) [with T = std::set<DirTree, std::less<DirTree>, std::allocator<DirTree> >, Archive = boost::archive::xml_oarchive, TPtr = DirTrees*]’ /usr/include/boost/archive/detail/oserializer.hpp:475: instantiated from ‘static void boost::archive::detail::save_pointer_type<Archive, TPtr>:: invoke(Archive&, TPtr) [with Archive = boost::archive::xml_oarchive, TPtr = DirTrees*]’ /usr/include/boost/archive/detail/oserializer.hpp:551: instantiated from ‘void boost::archive::save(Archive&, const T&) [with Archive = boost:: archive::xml_oarchive, T = DirTrees*]’ /usr/include/boost/archive/basic_xml_oarchive.hpp:84: instantiated from ‘void boost::archive::basic_xml_oarchive<Archive>::save_override(const boost::serialization::nvp<T>&, int) [with T = DirTrees* const, Archive = boost::archive::xml_oarchive]’ /usr/include/boost/archive/detail/interface_oarchive.hpp:80: instantiated from ‘Archive& boost::archive::detail::interface_oarchive<Archive>:: operator<<(const T&) [with T = boost::serialization::nvp<DirTrees* const>, Archive = boost::archive::xml_oarchive]’ ../../cppgraph/src/serialization.h:35: instantiated from ‘void Iterator<Container>::save(Archive&, unsigned int) const [with Archive = boost::archive::xml_oarchive, Container = DirTrees]’ /usr/include/boost/serialization/access.hpp:90: instantiated from ‘static void boost::serialization::access::member_save(Archive&, const T&, unsigned int) [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ /usr/include/boost/serialization/split_member.hpp:42: instantiated from ‘static void boost::serialization::detail::member_saver<Archive, T>::invoke( Archive&, const T&, unsigned int) [with Archive = boost::archive:: xml_oarchive, T = Iterator<DirTrees>]’ /usr/include/boost/serialization/split_member.hpp:63: instantiated from ‘void boost::serialization::split_member(Archive&, T&, unsigned int) [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ ../../cppgraph/src/serialization.h:46: instantiated from ‘void Iterator<Container>::serialize(Archive&, unsigned int) [with Archive = boost::archive::xml_oarchive, Container = DirTrees]’ /usr/include/boost/serialization/access.hpp:106: instantiated from ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ /usr/include/boost/serialization/serialization.hpp:78: instantiated from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ /usr/include/boost/serialization/serialization.hpp:121: instantiated from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ /usr/include/boost/archive/detail/oserializer.hpp:148: instantiated from ‘void boost::archive::detail::oserializer<Archive, T>::save_object_data (boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::archive::xml_oarchive, T = Iterator<DirTrees>]’ ../../cppgraph/src/serialization.cc:40: instantiated from here /usr/include/boost/archive/detail/interface_oarchive.hpp:60: warning: unused parameter ‘t’ Moreover, I normally treat warnings as errors (with -Werror); which is impossible when a third party library generates warnings. -- Carlo Wood <carlo(a)alinoe.com>

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