- Boost-users - lists.boost.org

Re: [Boost-users] problem... maybe boost could help
by Ovanes Markarian 27 Jun '07

27 Jun '07

My idea is based on fact that you (program developer or another developer) know what is going to be send. What you are trying to do is erasing the type to some base and that would not work. So you send event must handle derived type and put it correctly to variant. A possible solution would be: template<class EventType_> void sendEvent(EventType_ const& ev) { m_eventContainer = ev; //<- now compiler knows exactly the type of ev m_derivedHelper->dispatchEvent(&m_eventContainer); } Best Regards, Ovanes On Fri, June 22, 2007 21:41, Lukasz wrote: > > Thanks for the fast reply. Your solution looked very good for my problem, so i tried to apply it. >However, there seems to be a problem. At the point when i call dispatchEvent (as in the below >example) is when i have the actual event to be sent. But i still only have a pointer to the base >class and by assigning it to the container, it always gets interpreted as a base event, even when >in reality it's some derived type. > > I tried a couple of approaches. In the first one, my variant contains only the derived type (base class is Event, derived is EventTest) , i.e. > > typedef boost::variant<EventTest> event_container; > > .... > event_container m_eventContainer; > ... > > void sendEvent(Event * event) > { > // Call Helper to dispatch the event to correct type > m_eventContainer = *event; > m_derivedHelper->dispatchEvent(&m_eventContainer); > } > > This won't work. The compiler complains that none of the overloads for >boost::detail::variant::make_initializer_node::apply can convert parameter 2. If i add the base >event type to the variant list, i.e. > > typedef boost::variant<Event, EventTest> event_container; > > it will work, but it will always trigger the processEvent with the base > class type. I haven't found any information as to how boost::variant treats a case of a pointer to >a base class (in this case, i'm not even actually passing the pointer but an object since for >pointers it just doesn't seem to work). Should it be able to automatically convert the type ? If >not, then i guess i'm back to square one, since i still can't cast the event... unless i maybe >misunderstood something ? The code i tried is pretty much what you gave me, with some minor >modifications. > > Thanks in advance for any further assistance. > > Lukasz K. > > [...]

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[filesystem] where is replace_extension
by frederic.bron＠alcan.com 27 Jun '07

27 Jun '07

In the documentation of filesystem (1.34.0), at this position: http://www.boost.org/libs/filesystem/doc/tr2_proposal.html#Header-filesyste… we can read : template <class Path> Path replace_extension(const Path & p, const typename Path::string_type & new_extension); However, in boost_1_34_0.tar.bz2, I cannot find replace_extension in any file. Where is it? Regards, F. Bron Avis : Ce message et toute pièce jointe sont la propriété d'Alcan et sont destinés seulement aux personnes ou à l'entité à qui le message est adressé. Si vous avez reçu ce message par erreur, veuillez le détruire et en aviser l'expéditeur par courriel. Si vous n'êtes pas le destinataire du message, vous n'êtes pas autorisé à utiliser, à copier ou à divulguer le contenu du message ou ses pièces jointes en tout ou en partie. Notice: This message and any attachments are the property of Alcan and are intended solely for the named recipients or entity to whom this message is addressed. If you have received this message in error please inform the sender via e-mail and destroy the message. If you are not the intended recipient you are not allowed to use, copy or disclose the contents or attachments in whole or in part.

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[interprocess] Interprocess and Daniel James'es unordered containers
by Aaron W. LaFramboise 27 Jun '07

27 Jun '07

I'm trying to use Daniel James'es unordered containers, from the vault, with Interprocess: typedef ip::allocator<T, ip::managed_windows_shared_memory::segment_manager> T_allocator; typedef typedef boost::unordered_set<T, T_hash, std::equal_to<T>, T_allocator> T_set; I get this error: boost\unordered\detail\hash_table_impl.hpp(419) : error C2039: 'destroy' : is not a member of 'boost::interprocess::allocator<T,SegmentManager>' The method 'destroy' is missing in CVS, even though its still present in the documentation at <http://cloud.prohosting.com/newfunk/boost/libs/interprocess/doc/html/boost/…>. Is there some other general-purpose allocator that would work here? Why is this method missing?

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Boost.Function and template function
by gast128 27 Jun '07

27 Jun '07

Dear all, I get a crash when I try to wrap a template function with Boost.Function. I use VStudio 2003 sp1. But maybe the used syntax is wrong: #include <boost/function.hpp> struct SomeClass { }; template <typename T> bool func_template(T* p) { return (p != NULL); } void example1() { bool (*pf) (SomeClass*) = &func_template<SomeClass>; boost::function<bool (SomeClass*)> fc1 = &func_template<SomeClass>; boost::function1<bool, SomeClass*> fc2 = &func_template<SomeClass>; boost::function<bool (SomeClass*)> fc3 = pf; fc1(NULL); //crashes fc2(NULL); //crashes also fc3(NULL); //ok } Wkr, me

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Wave lib - MS compatibility issue?
by NeBlackCat 26 Jun '07

26 Jun '07

Firstly hi everybody - this is my first post, and I'm just finding my feet with Boost:Wave. I've built and am playing with the wave driver (wave.exe) on an existing open source project, but I get an "error: ill formed preprocessor directive: import" error with the at a line: #import <msado15.dll> \ rename("EOF","adoEOF") \ no_namespace I thought this might have been an MS compatibility thing, as importing COM type libraries is obviously Windows-specific (and afaik #import does something different in GCC), but I've tried recompiling with BOOST_WAVE_SUPPORT_MS_EXTENSIONS (and have tried lots of other things) and it doesn't make any difference. Google hasn't shown anything up either. Does anyone know if I can turn this error off somehow?

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[Boost.MPL] mpl::find<Types, T> not allowed in with T as template<typename T> argument?
by Manuel Jung 26 Jun '07

26 Jun '07

Hi, I have a short question. ----------- typedef boost::mpl::vector<double, int> Types; template<typename T> void send(){ typedef boost::mpl::find<Types, T>::type iter_T; //Doesn't compile typedef boost::mpl::find<Types, int>::type iter_T_static; //Compiles } ------------ I want the first cersion with my own Template Type. But the compiler gives me somthing like "Not enough Template arguments". (My Compiler outputs me german error messages...) Am i not allowed using my own template arguments with boost::mpl::find? Or what do i have to change? Thanks! Manuel Jung

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how do I use boost::iostreams::code_converter with GNU codecvt<.., ..., __gnu_cxx::encoding_state>?
by 宋浩 26 Jun '07

26 Jun '07

the GNU libstdc++ offers a flexible character encoding convertion primitive (essentially a wrapper for the iconv C API), but in a non-standard partial specialization of codecvt. for example, if I want to use this codecvt, to convert between internal encoding UCS-4LE and external encoding GB18030 (which is China's national standard for Chinese character encoding), I will write // define the codecvt type typedef std::codecvt<wchar_t, char, __gnu_cxx::encoding_state> w_codecvt; // define a std::locale instance only for codecvt purpose std::locale loc(std::locale::classic(), new w_codecvt); const w_codecvt &cvt = std::use_facet<w_codecvt>(loc); // the internal/external character encoding is specified as the // argument to the constructor of __gnu_cxx::encoding_state w_codecvt::state_type state("UCS-4LE", "GB18030"); // use cvt and state cvt.in(state, ...); the problem is, if I want to use this codecvt<.., .., __gnu_cxx::encoding_state> with code_converter, I can't find a way to tell code_convert the encoding names (UCS-4LE, GB18030), seems that code_converter will always use the default constructor of Codecvt::state_type. And if I specify the Codecvt template argument of code_converter to codecvt<.., .., encoding_state>, imbue() will become a no-op, which makes things even worse. BTW: the documentation for GNU libstdc++ codecvt is available here http://gcc.gnu.org/onlinedocs/libstdc++/22_locale/codecvt.html

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wrt my last post with (No Subject)
by jono 26 Jun '07

26 Jun '07

i've solved the problem, thanks. it was me. sorry about the missing subject line. jono

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(no subject)
by jono 26 Jun '07

26 Jun '07

hi all. i'm using boost::state_chart in a serial protocol handler. i have some code that collects characters in each state object by calling Protocol::input(byte) on the state machine, which then dispatches events in response to control bytes and for all other bytes, calls ICharacterInput .... . . state_cast< const ICharacterInput & >().input(c); . . ... which stores the new character in the base class ICharacterInput. i then process the stored characters in the the state's destructor. i've used very similar boost code in a number of protocol handlers and it works great. ...but.. this handler intermittently throws exceptions in boost/statechart/simple_state.hpp when it tries to downcast and delete a pointer to the state. does anybody have any suggestions where i should look to see what's going on? in particular, is the downcast/delete sequence going to be calling any code in my own base class destructors? the destructor in which the exception is thrown (and caught) seems to complete its own instructions without problems. this protocol only uses the EvStartOfHeader and EvEndOfText events. cheers jono poff ==================================================== ==================================================== ===================================== my header file ... struct EvStartOfHeader : sc::event< EvStartOfHeader > {}; struct EvStartOfText : sc::event< EvStartOfText > {}; struct EvEndOfText : sc::event< EvEndOfText > {}; struct EvEndOfTransmission : sc::event< EvEndOfTransmission > {}; struct EvReset : sc::event< EvReset > {}; struct Waiting; struct Decoding; struct Reset; struct RcvHeader; struct RcvText; struct Protocol: sc::state_machine< Protocol, Waiting > , IProtocol { Protocol(); ~Protocol(); virtual const char **input(byte c); }; struct Waiting : ICharacterInput, sc::state< Waiting, Protocol> { Waiting( my_context ctx ); ~Waiting(); typedef sc::transition< EvStartOfHeader, Decoding > reactions; }; struct Decoding: ICharacterInput, sc::state< Decoding, Protocol, RcvText> { Decoding( my_context ctx ); ~Decoding(); typedef sc::transition< EvReset, Waiting > reactions; }; struct RcvHeader : ICharacterInput, sc::state< RcvHeader, Decoding> { RcvHeader( my_context ctx ); ~RcvHeader(); typedef sc::transition< EvStartOfText, RcvText > reactions; }; struct RcvText : ICharacterInput, sc::state< RcvText, Decoding> { RcvText( my_context ctx ); ~RcvText(); typedef sc::transition< EvEndOfText, Waiting > reactions; }; ======================================================= ======================================================= ======================================================= ======================================================= ======== so what happens is: ======== in my dispatch code ... . . case ETX:// End of Text process_event( EvEndOfText() ); . . ======== results in ... . . =========================================== =========================================== == in boost/statechart/simple_state.hpp ... ======== ======== ======== a call to simple_state::exit_impl() {...} ======== results in call to .... . . intrusive_ptr & operator=(T * rhs) { this_type(rhs).swap(*this); return *this; } . . ======== with rhs == 0 ======== then delete throws here ... . . . template< class MostDerived, class Context, class InnerInitial, history_mode historyMode > inline void intrusive_ptr_release( const ::boost::statechart::simple_state< MostDerived, Context, InnerInitial, historyMode > * pBase ) { if ( pBase->release() ) { // The cast is necessary because the simple_state destructor is non- // virtual (and inaccessible from this context) delete polymorphic_downcast< const MostDerived * >( pBase ); } } . . . ============================ ============================ ============================ ============================

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[asio] Any IsConnected() method?
by Sunsawe 25 Jun '07

25 Jun '07

Hi, I would just like to know if there is a simple way to check wether or not a socket is still connected or not. And for a ssl socket? Thanks -- View this message in context: http://www.nabble.com/-asio--Any-IsConnected%28%29-method--tf3978649.html#a… Sent from the Boost - Users mailing list archive at Nabble.com.

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