January 2007 - Boost-users - lists.preview.boost.org

How am I misusing boost::lambda::bind?
by Jason House 05 Jan '07

05 Jan '07

I hope the sheer size of this post doesn't scare those who can help me away :( Depending on how I use the code at the bottom of this post, things either work or they blow up with varying error messages deep within the boost libraries. The very last function in the code below is the last consistent "source" of the errors. As best as I understand it, that line is correct. I'm scratching my head on how to diagnose what's going wrong. The simplest error I got seemed to complain about const qualifiers that seem to have been added internally to boost::lambda::bind. I'm not sure which error message to pick out from other error scenarios (such as 3 input parameters (types T0, T1, and T2)). This error had R0=void, and no input arguments (T0, T1, etc...). The code at the bottom of this post compiles with R0=void and T0=int. actions.hpp:87: error: no matching function for call to ‘boost::lambda::function_adaptor< GTPInternalResponse (*)( boost::function0<void, std::allocator<boost::function_base> >*, GTPCommand)> ::apply( GTPInternalResponse (* const&)( boost::function0<void, std::allocator<boost::function_base> >*, GTPCommand), boost::function0<void, std::allocator<boost::function_base> >* const&)’ As clarification for understanding the code: GTPInternalResponse can be thought of a string and GTPCommand as a tokenized string. The extract<>() function consumes some string tokens and returns a value of the specified type (T0,T1,T2,T3, etc...) The only big impact on this code externally (besides the calls to GTPFunctionObjectN) is #define's for GTP_PARAM_COUNT and GTP_PARAM_COUNT_PLUS_ONE. GTP_PARAM_COUNT_PLUS_ONE == GTP_PARAM_COUNT. The useful range for GTP_PARAM_COUNT is between 0 and 3 (inclusive). > #include <boost/preprocessor/enum_params.hpp> // expands for 0 ... N-1 > #include <boost/preprocessor/repetition/enum_shifted_params.hpp> // expands for 1 ... N-1 > > #if GTP_PARAM_COUNT == 0 > # define GTP_OPTIONAL_COMMA > #else > # define GTP_OPTIONAL_COMMA , > #endif > > > // GTP_PARMS expands to " typename T0, typename T1, typename T2" if GTP_PARAM_COUNT is 3 > #define GTP_TEMPLATE_PARAMS BOOST_PP_ENUM_PARAMS(GTP_PARAM_COUNT, typename T) > > // expands to "typename R0 , typename T0, typename T1, typename T2" if GTP_PARAM_COUNT is 3 > #define GTP_FULL_TEMPLATE_PARAMS typename R0 GTP_OPTIONAL_COMMA GTP_TEMPLATE_PARAMS > > // GTP_PARAM expands to " T3 a3" if INDEX is 3 > #define GTP_PARAM(UNKNOWN1,INDEX,UNKNOWN2) BOOST_PP_CAT(T,I) BOOST_PP_CAT(a,I) > > // GTP_PARAMS expands to " T0 a0, T1 a1, T2 a2" if GTP_PARAM_COUNT is 3 > #define GTP_PARAMS BOOST_PP_ENUM(GTP_PARAM_COUNT,GTP_PARAM,BOOST_PP_EMPTY) > > // GTP_PARAM_TYPES expands to " T0, T1, T2" if GTP_PARAM_COUNT is 3 > #define GTP_PARAM_TYPES BOOST_PP_ENUM_PARAMS(GTP_PARAM_COUNT, T) > > // expands to "R0 , T0, T1, T2" if GTP_PARAM_COUNT is 3 > #define GTP_FULL_PARAM_TYPES R0 GTP_OPTIONAL_COMMA GTP_PARAM_TYPES > > // GTP_PARAM_NAMES expands to " a0, a1, a2" if GTP_PARAM_COUNT is 3 > #define GTP_PARAM_NAMES BOOST_PP_ENUM_PARAMS(GTP_PARAM_COUNT, a) > > // expands to "boost::function3 < R0 , T0, T1, T2 >" when GTP_PARAM_COUNT is 3 > #define GTP_BOOST_FUNCTION BOOST_PP_CAT(boost::function,GTP_PARAM_COUNT) < GTP_FULL_PARAM_TYPES > > > // expands to "boost::function3 < void , T0, T1, T2 >" when GTP_PARAM_COUNT is 3 > #define GTP_BOOST_FUNCTION_VOID BOOST_PP_CAT(boost::function,GTP_PARAM_COUNT) < void GTP_OPTIONAL_COMMA GTP_PARAM_TYPES > > > // expands to type_wrapper3 when GTP_PARAM_COUNT is 3 > #define GTP_TYPE_WRAPPER BOOST_PP_CAT(type_wrapper,GTP_PARAM_COUNT) > > ////////////////////////////////////////////////////////////// > // gtp_detail::type_wrapper for converting all input arguments > namespace gtp_detail{ > > template < GTP_FULL_TEMPLATE_PARAMS > > struct GTP_TYPE_WRAPPER{ > static GTPInternalResponse wrap(GTP_BOOST_FUNCTION *(callback_function), GTPCommand cmd){ > unsigned int position = 0; > /// \bug Must figure out how to auto generate this repetative body > #if GTP_PARAM_COUNT >= 1 > assert(position < cmd.GetArgumentCount()); > T0 a0 = extract<T0>(cmd, position); > #endif > #if GTP_PARAM_COUNT >= 2 > assert(position < cmd.GetArgumentCount()); > T1 a1 = extract<T1>(cmd,position); > #endif > #if GTP_PARAM_COUNT >= 3 > assert(position < cmd.GetArgumentCount()); > T2 a2 = extract<T2>(cmd,position); > #endif > assert(position == cmd.GetArgumentCount()); > return converter<R0, GTPInternalResponse>( (*callback_function)(GTP_PARAM_NAMES) ); > } > }; > > template < GTP_TEMPLATE_PARAMS > > struct GTP_TYPE_WRAPPER < void GTP_OPTIONAL_COMMA GTP_PARAM_TYPES >{ > static GTPInternalResponse wrap(GTP_BOOST_FUNCTION_VOID *(callback_function), GTPCommand cmd){ > unsigned int position = 0; > /// \bug Must figure out how to auto generate this repetative body > #if GTP_PARAM_COUNT >= 1 > assert(position < cmd.GetArgumentCount()); > T0 a0 = extract<T0>(cmd, position); > #endif > #if GTP_PARAM_COUNT >= 2 > assert(position < cmd.GetArgumentCount()); > T1 a1 = extract<T1>(cmd,position); > #endif > #if GTP_PARAM_COUNT >= 3 > assert(position < cmd.GetArgumentCount()); > T2 a2 = extract<T2>(cmd,position); > #endif > assert(position == cmd.GetArgumentCount()); > (*callback_function)(GTP_PARAM_NAMES); > return GTPInternalResponse(); > } > }; > > }; > > /////////////////////////////////////////////////////// > // GTPCommandCallBack accepting a boost function object > > // expands to GTPFunctionObject3 when GTP_PARAM_COUNT is 3 > #define GTP_COMMAND_CALLBACK BOOST_PP_CAT(GTPCommandCallBack,GTP_PARAM_COUNT) > > // expands to " boost::lambda::_1, boost::lambda::_2, boost::lambda::_3" if GTP_PARAM_COUNT is 3 > #define GTP_LAMBDA_PARAMS BOOST_PP_ENUM_SHIFTED_PARAMS(GTP_PARAM_COUNT_PLUS_ONE, boost::lambda::_) > > template< GTP_FULL_TEMPLATE_PARAMS > inline > GTPFunctionObject* GTP_COMMAND_CALLBACK(GTP_BOOST_FUNCTION *callback_function){ > return new GTPFunctionObject(boost::lambda::bind((&gtp_detail::GTP_TYPE_WRAPPER<GTP_FULL_PARAM_TYPES>::wrap), callback_function GTP_OPTIONAL_COMMA GTP_LAMBDA_PARAMS)); > }

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[spirit] closures and actions
by Hugh Hoover 04 Jan '07

04 Jan '07

I'm trying to build a parser that does a fairly simple transformation of an input string - kind of like an L-System. I can get rules to properly match the input string, but I'm having real trouble with DOING anything. For testing, I've created some simple actions and a grammar (and rules) with a closure. When I don't use the closure for "temporary" variables, I seem to be able to proceed, but when I do anything except assign a value to my closure result, I'm getting failures to compile. This is using gcc4.01 on MacOSX and spirit 1.8.3 (from boost 1.34). The specific compiler error is: ../../src/lsystem/catalog_lsystem.cpp: In member function 'void do_appender::act(T&, const IteratorT&, const IteratorT&) const [with T = phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, IteratorT = __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >]': <snip> ../../src/lsystem/catalog_lsystem.cpp:211: error: no matching function for call to 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string (phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >&)' From the error, it appears that I need some transformation from phoenix::actor back into my closure member, which is a String (typedef for std::basic_string<char>). Any suggestions? do_appender (a simple example actor) looks like: struct do_appender { template <typename T, typename ValueT> void act(T& ref, ValueT const &val) const { ref += val; } template <typename T, typename IteratorT> void act(T& ref, IteratorT const &first, IteratorT const & last) const { String s(first, last); ref += s; } }; template <typename T> inline ref_value_actor<T, do_appender> do_append(T& lhs) { return ref_value_actor<T, do_appender>(lhs); } template <typename T, typename ValueT> inline ref_const_ref_actor<T, ValueT, do_appender> do_append(T& lhs, ValueT const& val) { return ref_const_ref_actor<T, ValueT, do_appender>(lhs,val); } and the closure and grammar (stripped slightly) look like: struct ProductionClosure : boost::spirit::closure<ProductionClosure, String, size_t, String> { member1 m_result; member2 m_count; member3 m_temporary; }; struct ParameterLSystem::ProductionGrammar : public grammar<ParameterLSystem::ProductionGrammar, ProductionClosure::context_t> { String * m_append; ProductionGrammar(String * ap) : m_append(ap) {} template <typename ScannerT> struct definition { typedef rule<ScannerT, ProductionClosure::context_t> rule_t; typedef rule<ScannerT> srule_t; srule_t r_segment; rule_t r_segments; srule_t r_leaf; rule_t r_leaves; srule_t r_push; srule_t r_pop; rule_t r_start; rule_t r_terminalLeaves; rule_t r_branch; rule_t r_top; definition(ProductionGrammar const& self) { // basics r_leaf = ch_p('L'); r_leaves = (+r_leaf)[r_leaves.m_result = construct_<String>(arg1, arg2)]; r_segment = ch_p('S'); r_segments = (+r_segment)[r_segments.m_result = construct_<String>(arg1, arg2)]; r_push = ch_p('['); r_pop = ch_p(']'); r_terminalLeaves = r_push[do_append (r_terminalLeaves.m_result)]; r_top = r_branch[self.m_result = arg1]; } rule_t const& start() const { return r_top; } }; }; }; String is a typedef for std::basic_string<char> in my namespace. When I use m_append for a "temporary", I can get things to "work", i.e., it compiles and generates the correct output but the grammar will get more complex and I don't believe I can get away without using a closure variable. The full error stack from the compiler is: ../../src/lsystem/catalog_lsystem.cpp: In member function 'void do_appender::act(T&, const IteratorT&, const IteratorT&) const [with T = phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, IteratorT = __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >]': ../../../../opensource/opt/include/boost/spirit/actor/ ref_value_actor.hpp:59: instantiated from 'void boost::spirit::ref_value_actor<T, ActionT>::operator()(const IteratorT&, const IteratorT&) const [with IteratorT = __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, T = phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, ActionT = do_appender]' ../../../../opensource/opt/include/boost/spirit/core/scanner/ scanner.hpp:146: instantiated from 'static void boost::spirit::attributed_action_policy<boost::spirit::nil_t>::call (const ActorT&, boost::spirit::nil_t, const IteratorT&, const IteratorT&) [with ActorT = boost::spirit::ref_value_actor<phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, do_appender>, IteratorT = __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >]' ../../../../opensource/opt/include/boost/spirit/core/scanner/ scanner.hpp:161: instantiated from 'void boost::spirit::action_policy::do_action(const ActorT&, AttrT&, const IteratorT&, const IteratorT&) const [with ActorT = boost::spirit::ref_value_actor<phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, do_appender>, AttrT = boost::spirit::nil_t, IteratorT = __gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >]' ../../../../opensource/opt/include/boost/spirit/core/composite/ actions.hpp:109: instantiated from 'typename boost::spirit::parser_result<boost::spirit::action<ParserT, ActionT>, ScannerT>::type boost::spirit::action<ParserT, ActionT>::parse(const ScannerT&) const [with ScannerT = boost::spirit::scanner<__gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::scanner_policies<boost::spirit::iter_policy_t, boost::spirit::match_policy, boost::spirit::action_policy> >, ParserT = boost::spirit::rule<boost::spirit::scanner<__gnu_cxx::__normal_iterator< char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::scanner_policies<boost::spirit::iter_policy_t, boost::spirit::match_policy, boost::spirit::action_policy> >, boost::spirit::nil_t, boost::spirit::nil_t>, ActionT = boost::spirit::ref_value_actor<phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, do_appender>]' ../../../../opensource/opt/include/boost/spirit/core/non_terminal/ impl/rule.ipp:233: instantiated from 'typename boost::spirit::match_result<ScannerT, ContextResultT>::type boost::spirit::impl::concrete_parser<ParserT, ScannerT, AttrT>::do_parse_virtual(const ScannerT&) const [with ParserT = boost::spirit::action<boost::spirit::rule<boost::spirit::scanner<__gnu_c xx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::scanner_policies<boost::spirit::iter_policy_t, boost::spirit::match_policy, boost::spirit::action_policy> >, boost::spirit::nil_t, boost::spirit::nil_t>, boost::spirit::ref_value_actor<phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >, do_appender> >, ScannerT = boost::spirit::scanner<__gnu_cxx::__normal_iterator<char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::scanner_policies<boost::spirit::iter_policy_t, boost::spirit::match_policy, boost::spirit::action_policy> >, AttrT = String]' ../../src/lsystem/catalog_lsystem.cpp:547: instantiated from here ../../src/lsystem/catalog_lsystem.cpp:211: error: no matching function for call to 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string (phoenix::actor<phoenix::closure_member<0, phoenix::closure<String, size_t, String> > >&)'

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Serialization : Deserializing members not present in archive
by Booster Booster 04 Jan '07

04 Jan '07

Hey, I have a class with a few data members that is serializable. Note that, I already have an archive ( test.txt ). Now, I want to serialize a couple more members. I went ahead and added the new members to my serialize functions. When I read from the archive ( test.txt ) , I get an exception. This is understandable, because the archive doesn't have the new members that I'm trying to read out. My question is, is there a way to check for the existence of a member before deserializing an object from the archive ? Thanks in advance, Sandeep.

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Re: [Boost-users] asio has a very confusing name - should be changed or made asynchronous
by Christopher Kohlhoff 04 Jan '07

04 Jan '07

Hi Marc, On Fri, 29 Dec 2006 11:15:12 +0100, "Marc Lehmann" <schmorp(a)schmorp.de> said: > I just saw that asio went into the boost cvs. > > I was interested because asio claims to provide an "asynchronous I/O > model", which sounds great. > > However, looking at current asio, there is nothing asynchronous, asio > is completely synchronous by API Hmmm, maybe we have different ideas about what an asynchronous I/O model looks like :) > (and on POSIX platforms): > > * the asio API is synchronous because it requires blocking calls to > io_service.run (), making it completely synchronous by API because > no I/O is done asynchronously to the program. The asio API is, not coincidentally, similar in design to the POSIX async I/O functions, as well as the Extended Sockets API (ES-API) also defined by the Open Group, and of course overlapped I/O on Windows. For example: * Asynchronous operations are initiated using a function call specific to the operation being requested: asio - basic_stream_socket::async_receive() POSIX aio - aio_read() ES-API - exs_recv() Windows - WSARecv() * The application must provide the buffer for the operation when calling the initiating function, and ensure that it remains valid (and also not attempt to access it) until the operation completes. * A blocking call is used to wait for operations to complete: asio - io_service::run() POSIX aio - aio_suspend() ES-API - exs_qdequeue() Windows - GetQueuedCompletionStatus() The main difference with asio is that, by default, it combines waiting for the operations to complete with dispatching the associated completion handler. > * on POSIX at least it calls select (or poll), which are synchronous > by nature (see > http://www.opengroup.org/onlinepubs/009695399/functions/select.html, > "select - synchronous I/O multiplexing"). Yes, the asio API can be implemented in terms of synchronous I/O demultiplexers, such as select (or epoll or kqueue). I see this as one of asio's key strengths, as it enables the API to be implemented portably. It is also intended that the API can be implemented in terms of native asynchronous I/O if available (and if the implementation actually has decent performance). This is currently the case for asio on Windows. The asio API is still asynchronous even if it is implemented in terms of a synchronous demultiplexer. All that the interface "says" is that when you initiate an asynchronous operation, the "observable behaviour" (i.e. the data copy to or from kernel space) will occur some time between the start of the initiating function until immediately before the completion handler is called. This means the observable behaviour is asynchronous with respect to the program's flow of control. > * it seems to work only on non-blocking filehandles on POSIX, either, so > file I/O is either not possible or not asynchronous. Asio doesn't do file I/O at this time (although it is planned for the future). > Is it planned to change the API into an asynchronous API and provide > asynchronous I/O later? If not, I think it might be better to change > the name into something that reflects the contents ("synchronous I/O > model sounds a bit boring, how about "network/nonlinear I/O model" or > even "standard I/O model"). > > Otherwise we would end up with a synchronous I/O model called > "asynchronous", which will likely confuse a lot of people who want a > real asynchronous I/O model (as provided by POSIX for example). > > Maybe asynchronous was confused with event-based when naming the > library? Just because I/O is not done linearly anymore does not mean > its not done in an asynchronous way, though. Of course, event-based programming and asynchronous I/O are not mutually exclusive. IMHO the asio API is both asynchronous and event-based in terms of what it provides to the library user. That asio can be implemented using synchronous mechanisms doesn't change this. Cheers, Chris

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Re: [Boost-users] COM and boost::intrusive_ptr
by Nat Goodspeed 04 Jan '07

04 Jan '07

________________________________________ From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Philipp Henkel Sent: Thursday, January 04, 2007 12:34 PM To: boost-users(a)lists.boost.org Subject: [Boost-users] COM and boost::intrusive_ptr 1. I need to access the address of the raw pointer (to use QueryInterface). Therefore I implemented operator& for intrusive_ptr. Like in COM this pointer-pointer will only be used for intialization purposes. My implementation relies on the intrusive_ptr's memory layout and returns reinterpret_cast<T**>(addressof(ptr)). I know, this is evil... CComPtr-like usage: boost::intrusive_ptr<IVideo> video; someObject->QueryInterface(IID_IVideo,(void**)&video); Is there a better way? How do you bring intrusive_ptr and QueryInterface together? [Nat] Sorry if this is naïve... Wouldn't it work to do something like this? IVideo* temp_video = NULL; someObject->QueryInterface(IID_IVideo, &temp_video); boost::intrusive_ptr<IVideo> video(temp_video);

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boost::bind - using boost::weak_ptr
by Remigiusz �ukowski 04 Jan '07

04 Jan '07

hello, Callback mechanism defined by boost::function and by means boost::bind instead of using callback virtual class is very comfortable, but has one big shortcoming: using callback class, passing object can be stored as weak_ptr and if weak_ptr is invalid the callback can be automatically unregistered. I've tried to implement such behaviour with boost::function and boost::bind with some helper class holding weak_ptr: template<typename T> class my_wptr { boost::weak_ptr<T> m_wptr; constructors etc... }; and two helper functions: template<typename T> T* get_pointer( my_wptr &_wptr ) { boost::shared_ptr<T> sptr = _wptr.m_wptr.lock(); if( !sptr ) throw some_exception; return _wptr.get(); } and template<typename T> my_wptr<T> wptr_from( boost::weak_ptr<T> &_sptr ) { return my_wptr( _sptr ); } now I can use standard shared_ptr version: boost::function<void()> f1 = boost::bind( &class::method, some_shared_ptr ); or my version holding weak_ptr: boost::function<void()> f2 = boost::bind( &class::method, wptr_from( some_weak_ptr )); This works, but is unsafe - after get_pointer succesfully returns pointer to the object, the object is unlocked and can be deleted during class::method execution. Can anyone help me solving this problem ? regards Remigiusz Zukowski, Poland --------------------- Panorama Internetu - prognoza pogody, poczta e-mail z największym załącznikiem, SMS, wyszukiwarki: Gooru, Anonser, serwisy: randki, ogłoszenia, wakacje, program TV, Kina, muzyka, DVD, newsy, inne. http://www.panoramainternetu.pl/ (http://www.epf.pl/)

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use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>
by Miguel Silvestre 04 Jan '07

04 Jan '07

Hi folks! I've just installed the serialization boost library and I'm trying to run it but I get the error in the subject. I'm trying to integrate the serialization in my project and for the begining I'm trying to follow the very simple example :-/. I've already searched the internet for this error, and I get some pages but without any answer... So here is the code: class A { private: friend class boost::serialization::access; int dumbi; float dumbf; template<class Archive> void serialize(Archive &ar, const unsigned int version) { ar & dumgf; ar & dumbi; } public: A():dumbi(12), dumbf(69.69f) { } A(int dumb1, float dumb2) : dumbi(dumb1), dumbf(dumb2) { } }; class SilvTask { private: typedef DefaultTask Parent; int dumbi; float dumbf; A testA; bool m_save, m_xml; std::string m_filename; public: SilvTask():m_save(false), dumbf(69.69f), dumbi(7), m_xml(false) { } int SilvTask::ParseArguments(const std::vector<std::string>& args) { for(uint32 i = 0; i < (uint32)args.size(); i++) { if(args[i].find("-xml")) m_xml = true; if(args[i].find("-save=") != std::string::npos) { m_filename = args[i].substr(6); m_save = true; } else if(args[i].find("-load=") != std::string::npos) { m_filename = args[i].substr(6); m_save = false; } } return FE_OK; } int SilvTask::LoadData() { if(m_save) WriteObject(); else LoadObject(); return FE_OK; } int SilvTask::WriteObject() { A aux(12, 69.69f); // create and open a character archive for output std::ofstream ofs(m_filename.c_str()); boost::archive::text_oarchive oa(ofs); //write class instance to archive oa << aux; return FE_OK; } int SilvTask::LoadObject() { A newAux; std::ifstream ifs(m_filename.c_str(), std::ios::binary); boost::archive::text_iarchive ia(ifs); // read class state from archive ia >> newAux; return FE_OK; } }; any ideias? Thanks -- Miguel Silvestre

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[asio] Address already in use / reuse_address
by Maximilian Szengel 04 Jan '07

04 Jan '07

Hi list, I am having problems using asio. When I create a server (or take one of the examples from the website), start it and connect to it via telnet, then close the server (by closing all sockets, so io_service::run returns) and then want to restart the server again, I always get: "Address already in use." asio::error exception. I tried setting asio::ip::tcp::acceptor::reuse_address(true), but that didn't change anything. Any help/hint would be appreciated. Greetings, Max

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mpl::inherit_linearly question
by Ovanes Markarian 04 Jan '07

04 Jan '07

Hi! I am trying to create a static visitor using metapgramming. This approach worked fine in some test code, but now I face some problems. Let me first show some example: I've define an item_visitor template class: template <class Pair> //mpl::pair obtained from map sequence struct item_visitor { public: typedef typename Pair::second value_type; virtual void visit(value_type const& t) { assert(0 && "This function must be overriden in the concrete handler class!"); } }; template<class Seq> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, item_visitor<boost::mpl::_2> > >::type {}; This example works fine and I can dispatch my type. Now I have some additional type, which provides a view to my structure. And I would like my visit to implemented as: virtual void visit(GenericView<Pair::second> const& t) { ... } In such a case I have to introduce a second parameter to the item_visitor template: template<class Pair, template<class> SomeView> struct item_visitor { ... }; Therefore the base_sequence_visitor must be updated as well to forward the View template: template<class Seq, template<class> SomeView> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, item_visitor<boost::mpl::_2, SomeView> > >::type {}; Using this construct I get an error, that mpl::arg<2> does not have a type second. That means that the placeholder _2 does not get expanded. So I tried to "code around" and used the following trick: template<class> calss SomeView; template<class Pair> struct some_visitor : item_visitor<Pair, SomeView> {}; Then I added to the base_sequence_visitor template an additional argument, which specifies an item visitor class to be used: template<class Seq, template<class> ItemVisitor> struct base_sequence_visitor : public boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, ItemVisitor<boost::mpl::_2> > >::type {}; And it compiles fine! But when I try to cast the base_sequence_visitor to some complete item_visitor type, which is really in the sequence I receive a compiler error, that cannot convert from 'base_sequence_visitor<Seq,ItemVisitor>' to 'ClassWhereSimpleVisitorIsDefined::simple_visitor<PairType> &' Do I miss something? With Kind Regards, Ovanes Markarian

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[graph] leda_graph.hpp: edge property maps
by Jens Müller 04 Jan '07

04 Jan '07

leda_graph.hpp has an adapter for leda::node_array's as property maps. Could the same code (replacing node by edge, where appropriate) be used to make an adapter for leda::edge_array's? Well, I'll try this out right now ...

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Mapping from type to value
by Johan Torp 04 Jan '07

04 Jan '07

What is the best practice for creating a map from a type to a value? Currently I do it like this: ===================================== struct SomeMap { template<typename T> static const std::string& LookUp(); }; template <> const std::string& SomeMap::LookUp<int>() { static const std::string s("int"); return s; } ===================================== ...but this seems far from optimal. -- System Developer TouchTable AB Tel: +46 (0)31 773 68 12 johan.torp(a)touchtable.se

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Simple MPL question: Generate code from type sequence
by Johan Torp 04 Jan '07

04 Jan '07

I would like to generate one call to a templated function for each type in an MPL sequence. Which is the best way to do this? E.g.: typedef vector<float,double,long double> SomeVector; template <typename T> write_size() { std::cout << sizeof(T) << " "; } Should somehow expand to: write_size<float>(); write_size<double>(); write_size<long double>(); I have managed to do this "manually" in a fairly general way, what I'm looking for is some part of boost which replaces my ForEach struct below or some nicer way of writing the same code: ============================================== struct WriteSize { template<typename T> void Call() {write_size<T>();} }; template <class It, class End> struct ForEach { template <class Func> static void Call(Func& func) { func.Call<typename It::type>(); ForEach<typename next<It>::type, End>::Call(func); } }; template <class End> struct ForEach<End, End> { template <class Func> static void Call(Func&) {} }; // Then I can generate the calls by WriteSize ws; ForEach<begin<SomeVector;>::type, end<SomeVector;>::type>::Call(ws); ============================================== -- System Developer TouchTable AB Tel: +46 (0)31 773 68 12 johan.torp(a)touchtable.se

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[BGL] How to get at a specific vertex and check out degree?
by Ferng, Andrew D 04 Jan '07

04 Jan '07

Hi all, I've been reading the docs and have gotten more and more confused. Figure I better stop and ask for directions. So far, I've been successful in using the following (basically copied the connected component example): adjacency_list<vecS, vecS, undirectedS> G; vector<int> linkPath(num_vertices(G)); int num = connected_components(G, &linkPath[0]); cout << "Total number of linkPaths: " << num << endl; So from the output of the algorithm, I examine all the different paths found and are interested in certain vertices. For example, for some component, I want to know if a certain vertex has degrees over 2. I'm using undirected so I assume out_degree will give me the total degrees? >From the docs: out_degree(vertex_descriptor u, const adjacency_list& g) and graph_traits<adjacency_list>::vertex_descriptor I think the 2nd param in out_degree is just G. But what about the first param? Is that like an iterator? how do I specify the vertex that I'm interested in? Thanks!

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Re: [Boost-users] [Boost.Multi-Index] ICE w/ VC7.1
by Marc Viala 03 Jan '07

03 Jan '07

De la part de John Maddock > Marc Viala wrote: > > Before trying to recompile some codes from B.MI/test to crash my > > compiler w/ an ICE, I've just played with some compilation options in > > my IDE and the results are: > > > > In Debug mode: > > If the C/C++ options "/Zi" & "/Gm" are set: KO -> w/ ICE in > > apply_wrap.hpp > > If the C/C++ options "/ZI" & "/Gm" are set: KO -> w/ ICE in > > apply_wrap.hpp > > If the C/C++ option "/Gm" is not set and "Zi" or "ZI" is set: OK > > > > > > In Release mode: > > with or without the "/Gm" option set: OK > > > > Funny... It seems that the /Gm option is quite unstable in debug > > mode? I don't know exactly the goal of this option but our project > > template set this option by default in this mode. > > > > Joaquin or John, do you know the meaning of this compilation option > > for VC7.1? Do you know the recommended options w/ this compiler to > > use Boost libraries, more specifically B.MI? For information, up to > > now, we use "/ZI" or "/Zi" in conjunction with "/Gm" option with all > > other Boost libraries. > > With apologies I think I misread your original post: I took your post to > mean you were seeing a runtime crash, but you mean an internal compiler > error: and I did see that at one point when testing your original code. I > use the same project options as you BTW /Zi and /Gm: the /Zi enables build > and continue, /Gm enables a minimal rebuild (compile only the changes to a > source). Generally they work quite well, but if you see an internal > compiler error the trick is just to do a clean, then rebuild, and that > usually clears the problem. Of course cleaning and rebuilding a large > project can wipe out the advantages that /Zi /Gm normally bring :-( Thanks a lot this explanation... It does clarify for me the signification of these options. Now that I'm aware of /Gm option behaviour I would pay more attention. > > Strangely I was unable to reproduce the internal error this morning no > matter options I used: it seems to be very dependent on whatever VC has in > it's cache. > Yes, that's a pity... I can now go ahead with B.MI. Best regards Marc

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Re: [Boost-users] [boost] Boost threads + MSVSC + /Za + client code
by Sohail Somani 03 Jan '07

03 Jan '07

Hi Anthony, Thanks for your response. > if BOOST_DISABLE_WIN32 is > defined and > BOOST_HAS_PTHREADS is not; the implication is that if you > can't use the > Windows headers, then you can't use the Windows thread API, > so if we haven't > got pthread-win32 configured, you can't use Boost threads. This pretty much sums it up, yes. > I am not sure what we can do about this. One issue is that > currently the > thread lib requires windows.h, and therefore compiler > extensions, when the > library sources are built. I'm not sure whether it is safe to > link something > compiled with extensions on against something compiled with > extensions off --- > is the ABI the same? If it *is* safe, then we should remove > this define from > boost/config/suffix.hpp, since the boost thread headers don't > explicitly > include windows.h. I think this is correct but I think the restriction only makes sense if you are building the thread library. Atleast the 1.33.1 code appears to have been written such that headers don't require language extensions. My gut feeling is that a solution like this should work: // BOOST_BUILDING is defined whenever building a boost library #if defined(BOOST_BUILDING) && defined(BOOST_MSVC) # define BOOST_REQUIRE_MSVC_LANGUAGE_EXTENSIONS #endif #include <boost/config/requires_threads.hpp> #if defined(BOOST_REQUIRE_MSVC_LANGUAGE_EXTENSIONS) # undef BOOST_REQUIRE_MSVC_LANGUAGE_EXTENSIONS #endif > OTOH, someone put the restriction there for a reason, and I > wouldn't want to > remove it without careful thought. Of course. Thanks again, Sohail

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Using serialization of a class with a wrapped shared_ptr - compil ation and run-time issues !!!
by Jon Belinfante 03 Jan '07

03 Jan '07

Hi I am at present introducing myself to Boost Serialization which from my first impressions of is very impressive to use and I like what I see. I have an ongoing set of classes to serialiise and find most of the problems I have found can be resolved from the Boost documentation. However one problem I have is that a huge bulk of my classes used boost::smart_ptrs each of which seem to add an extra level of complexity and at present I can not see my own resolution to. I have one simple case of a smart string class - as shown below which causes me a problem. This source code is to create a smart string class which uses a wrapped shared_ptr to a std::string - the idea behind this Smart String class is to reduce memory sizes for huge quantity of repeated strings in an application. -Please see source code. This class works fine apart the serialization which either does not compile or crashes with assertion errors. Please see below source code. As this code stands with line in the serialization block ar & m_stringPtr; I get a long compilation error - c:\Boost\boost_1_33_1\boost\serialization\shared_ptr.hpp(235) : error C2027: use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' - with it complatining with the line oa << a; which is in the main code block. However if I change to code ar & * m_stringPtr; The code compiles correctly and it serializes the SmartString - however it run-time throws in trying to de-serialise at ia >> b; Any ideas here where I am going wrong - I would be most greatful. Thanks /********************************************/ #include <set> #include <vector> #include <string> #include <boost/shared_ptr.hpp> #include <boost/scoped_ptr.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/shared_ptr.hpp> BOOST_SERIALIZATION_SHARED_PTR(std::string) /** Smart String Class Basically holds a String only by a ptr and the pimpl method. Idea is to only ever store a shared_ptr and let boost do a reference count on its usage. Idea to of course save time/speed of string storage. */ class SmartString { public: /** overriden stream operator */ friend std::ostream& operator<< (std::ostream &os, const SmartString &cSmartString); SmartString() { m_stringPtr.reset(); } SmartString( const std::string& s) { boost::shared_ptr< std::string > tempPtr( new std::string( s) ); m_stringPtr = tempPtr; } SmartString( const char* s) { boost::shared_ptr< std::string > tempPtr( new std::string( s) ); m_stringPtr = tempPtr; } SmartString( const SmartString& other) { m_stringPtr = other.m_stringPtr; } SmartString& operator=(const SmartString& other) { m_stringPtr = other.m_stringPtr; return *this; } inline SmartString& operator=( const std::string& otherStr) { boost::shared_ptr< std::string > tempPtr( new std::string( otherStr) ); m_stringPtr = tempPtr; return *this; } bool operator() ( const SmartString& t1, const SmartString& t2) const; inline bool operator<( const SmartString& otherStr) { const std::string other= *otherStr.m_stringPtr; return *m_stringPtr < other; } inline bool operator<=( const SmartString& otherStr) { const std::string other= *otherStr.m_stringPtr; return *m_stringPtr <= other; } inline bool operator>( const SmartString& otherStr) { const std::string other= *otherStr.m_stringPtr; return *m_stringPtr > other; } inline bool operator>=( const SmartString& otherStr) { const std::string other= *otherStr.m_stringPtr; return *m_stringPtr >= other; } inline bool operator==( const SmartString& otherStr ) { return *m_stringPtr == *otherStr.m_stringPtr; } inline bool operator==( const SmartString& otherStr ) const { return *m_stringPtr == *otherStr.m_stringPtr; } inline bool operator==( const std::string& otherStr ) { return *m_stringPtr == otherStr; } inline bool operator==( const char* c ) { int x = ::strcmp( (*m_stringPtr).c_str(), c); return x? false:true; } inline const std::string& getString( ) const { return *m_stringPtr; } inline bool operator!=( const SmartString& otherStr) { const std::string other= *otherStr.m_stringPtr; return *m_stringPtr != other; } inline bool operator!= ( const std::string& otherStr) { return *m_stringPtr != otherStr; } inline const char& operator[] (const int index) const { if ( (index >=0) && ( index <= static_cast<int>((*m_stringPtr).size() ))) return (*m_stringPtr)[index]; else { std::string message( "Out of range index on " + (*m_stringPtr) ); throw std::out_of_range(message); } } /** overriden + operation to retunn addition of two strings */ friend SmartString operator+(const SmartString& s1,const SmartString &s2); virtual ~SmartString(){} friend class boost::serialization::access; protected: template <class Archive> void serialize ( Archive& ar, const unsigned long file_version) { ar & m_stringPtr; } boost::shared_ptr<std::string> m_stringPtr; }; std::ostream& operator<< (std::ostream &os, const SmartString& cSmartString) { const std::string str( cSmartString.getString() ); os << str.c_str(); return os; } SmartString operator+(const SmartString& s1,const SmartString &s2) { std::string str = s1.getString(); str += s2.getString(); return SmartString ( str.c_str() ); } int main( int, const char*[] ) { const SmartString a("ABC"); const char* fileName = "smartStringFile"; { std::ofstream ofs(fileName); boost::archive::text_oarchive oa( ofs ); oa << a; } SmartString b; { std::ifstream ifs( fileName, std::ios::binary ); boost::archive::text_iarchive ia( ifs ); ia >> b; } } /********************************************/ ********************************************************** Mitsubishi UFJ Securities International plc ("MUSI") is registered in England, company number 1698498 and registered office at 6 Broadgate, London EC2M 2AA. MUSI is part of the Mitsubishi UFJ Financial Group and is authorised and regulated by The Financial Services Authority. This message is intended solely for the individual addressee named above. The information contained in this e-mail is confidential and may be legally privileged. If you are not the intended recipient please delete in its entirety. Messages sent via this medium may be subject to delays, non-delivery and unauthorised alteration. The information contained herein or attached hereto has been obtained from sources we believe to be reliable but we do not represent that it is accurate or complete. Any reference to past performance should not be taken as an indication of future performance. The information contained herein or attached hereto is not to be construed as an offer or solicitation to buy or sell any security, instrument or investment. MUSI or any affiliated company, may have an interest, position, or effect transactions, in any investment mentioned herein. Any opinions or recommendations expressed herein are solely those of the author or analyst and are subject to change without notice.

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Using filter_iterator in a for loop
by David Ward 03 Jan '07

03 Jan '07

I want to use a boost::filter_iterator to iterate through a std::vector using a for-style loop. I haven't been able to find any examples of the proper way to do this in the Boost documentation (or how to do this for any other Boost iterator, for that matter). >From searching this newsgroup, I found that it is possible to do: for (boost::filter_iterator< ... > iter(myVector.begin(), myVector.end()); iter != boost::filter_iterator< ... >(myVector.end()); ++iter ) { ... } However, iter is quite aware of when it has reached the end of the vector, since that is the second parameter in its constructor. Is it really necessary to create a second filter_iterator, set it to the end of the vector, and then test iter against it? Can't I somehow test iter alone to see if it has reached the end of the vector? If I use std::for_each, it needs both a beginning and ending iterator as parameters, leading to the same situation as above. I've also looked at the Boost Range library and BOOST_FOREACH (described at http://www.boost.org/regression-logs/cs-win32_metacomm/doc/html/foreach.html) However, from my understanding, I don't think either of these apply to or work with Boost iterators. Whatever method is appropriate, I would ask that someone please exapnd the Boost iterator documentation to include an example of using Boost iterators in a for-style loop. I feel that this is a very basic and common usage of iterators which was not addressed. Thank you. -- David Ward Communications and Networking Division Information Technology and Telecommunications Laboratory Georgia Tech Research Institute

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Re: [Boost-users] [Boost.Multi-Index] ICE w/ VC7.1
by Marc Viala 03 Jan '07

03 Jan '07

Hello Joaquin & John, > > > So I gave up at that point. Adding your example programs to the > > same VC7.1 IDE project did compile so I don't think it's a > > setup issue. > > That's fine, your help has been invaluable. It definitely > looks like a local problem, I hope Marc can provide me with > more info wrt his particular environment. Thank you very much, Thanks for your help John. Before trying to recompile some codes from B.MI/test to crash my compiler w/ an ICE, I've just played with some compilation options in my IDE and the results are: In Debug mode: If the C/C++ options "/Zi" & "/Gm" are set: KO -> w/ ICE in apply_wrap.hpp If the C/C++ options "/ZI" & "/Gm" are set: KO -> w/ ICE in apply_wrap.hpp If the C/C++ option "/Gm" is not set and "Zi" or "ZI" is set: OK In Release mode: with or without the "/Gm" option set: OK Funny... It seems that the /Gm option is quite unstable in debug mode? I don't know exactly the goal of this option but our project template set this option by default in this mode. Joaquin or John, do you know the meaning of this compilation option for VC7.1? Do you know the recommended options w/ this compiler to use Boost libraries, more specifically B.MI? For information, up to now, we use "/ZI" or "/Zi" in conjunction with "/Gm" option with all other Boost libraries. Thanks for your help. The code snipped during my compilation test is the following: #include <boost/config.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/composite_key.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/key_extractors.hpp> // STL #include <string> using namespace boost::multi_index ; struct Item { const std::string& getCls() const { return _cls ; } const std::string& getId() const { return _id ; } std::string _cls ; std::string _id ; int _i ; int _j ; } ; void main() { typedef const_mem_fun< Item , const std::string& , &Item::getCls > key_cls ; typedef const_mem_fun< Item , const std::string& , &Item::getId > key_id ; typedef composite_key<Item,key_cls,key_id> ckey_clsid ; typedef multi_index_container< Item, indexed_by< ordered_non_unique<key_id> , ordered_non_unique<key_cls> , ordered_unique<ckey_clsid> > > ObjectContainer ; ObjectContainer c ; }

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Re: [Boost-users] Boost threads + MSVSC + /Za + client code
by Sohail Somani 03 Jan '07

03 Jan '07

Hi, Any takers? The workaround I've found for the problem below is to #define _MSC_EXTENSIONS before including any boost thread headers. It /appears/ that this is only necessary when separately compiling boost threads. Sorry for the cross-post. > With Visual C++, I can't seem to determine why if I simply include > boost/threads/once.hpp, I need to enable language extensions for that > translation unit. I'm going to dig into this further today but I would > appreciate if someone has figured out a solution short of allowing > language extensions. I can understand requiring it for building boost > threads (as windows.h seems to have some extended syntax) but I'm not > sure of the logic behind requiring client code to use it as well. Thanks! Sohail

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[threads] Compiling boost.threads on Linux
by Hugo Vinicius Alves Soares 03 Jan '07

03 Jan '07

Hey everybody, I'm a newbie on Boost Libraies, I'm starting with the thread library. I'm using Ubuntu and a install it using apt-get, the headers are in /usr/include/boost/ but when I use g++ to compile my test codes an error message is returned: undefined reference to methods of the library classes. I know this errors are link errors, what option I must pass to g++? Thanks for everyone that answer my ask. Hugo Vinícius __________________________________________________ Fale com seus amigos de graça com o novo Yahoo! Messenger http://br.messenger.yahoo.com/

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Re: [Boost-users] [Boost.Multi-Index] ICE w/ VC7.1
by Marc Viala 02 Jan '07

02 Jan '07

Hello Joaquin and happy New Year, Sorry for my late reply but our mail server was down in the night of 31th; this is not a joke. I've just changed the code snippet with your recommendation but without success: I've got the same ICE with VC7.1. Just to clarify my report: I've also compiled some code snippets from the MultiIndex documentation and get the same ICE. My compiler version corresponds to the VC7.1 with the service pack #1. Best regards, Marc Viala > -----Message d'origine----- > De : boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] De > la part de "JOAQUIN LOPEZ MU?Z" > Envoyé : dimanche 31 décembre 2006 01:08 > À : boost-users(a)lists.boost.org > Objet : Re: [Boost-users] [Boost.Multi-Index] ICE w/ VC7.1 > > Hello Marc, > > ----- Mensaje original ----- > De: Marc Viala <mviala(a)acticm.com> > Fecha: Viernes, Diciembre 29, 2006 7:25 pm > Asunto: [Boost-users] [Boost.Multi-Index] ICE w/ VC7.1 > Para: boost-users(a)lists.boost.org > > > I'm just trying to use Boost.MultiIndex in a large project but I'm > not > > being able to compile this library with VC 7.1.6030: I've got an > > ICE in file "apply_wrap.hpp" of Boost.MPL. I've tried to change the > > headers order but without success. > > > > My environment is: > > - Windows XP > > - Boost 1.33.1 > > - VC 7.1.6030 > > > > To demonstrate this ICE, you will find hereafter a code snippet. > > > > Thanks in advance. > > > > Marc Viala > [...] > > typedef composite_key< > > Item > > , ordered_non_unique<member<Item,int,&Item::_i> > > > , ordered_non_unique<member<Item,int,&Item::_j> > > > > ckey_ij ; > > I think the problem lies here: you must provide composite_key<> > with *key extractors*, not index specifiers. Please try > rewriting ckey_ij like this: > > typedef composite_key< > Item > , member<Item,int,&Item::_i> > , member<Item,int,&Item::_j> > > ckey_ij ; > > Problem solved? I'm sorry I can't try the snippet you > provide myself, so please report back. Thanks for using > Boost.MultiIndex! > > Joaquín M López Muñoz > Telefónica, Investigación y Desarrollo > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] fatal error LNK1561: entry point must be definedbuilding boost libs with win32 port of pthread
by Andrew Marlow 02 Jan '07

02 Jan '07

boost-users-bounces(a)lists.boost.org wrote: > "Andrew Marlow" <Andrew.Marlow(a)icap.com> writes: > >> I am trying to build boost using the win32 port of pthreads. Although I got it working I did have to apply a small hack which I feel I have to mention. The file lib/thread/build/threads.jam refers to the PTW32_LIB directory via a subdirectory pre-built. So unless the lib and include subdirs are in a subdir called 'pre-built' it does not work. I removed "/pre-built" from the jam file and then all was ok. I am not sure why 'pre-built' is there since a pre-built library can be installed in any location that people want. Shouldn't this be removed? If not then perhaps PTW32_LIB can be added as additional directory to search for the lib and include files without the 'pre-built' qualifier. Regards, Andrew Marlow ******************************************************************************" The data and information (collectively called Information) herein is the sole property of ICAP. The Information is confidential, may be legally privileged and is intended solely for the use of the individual or entity to whom it is addressed. Unauthorised disclosure, copying or distribution of the Information is strictly prohibited and the recipient of the Information shall not redistribute the Information in any form to a third party. If you received this Information in error please tell us by reply (or telephone the sender) and delete all copies on your system. References in this Information to ICAP are references to ICAP plc, a company incorporated in England with registered number 3611426 whose registered office is 2 Broadgate, London, EC2M 7UR and where the context requires, includes its subsidiary and associated undertakings. As applicable, certain companies within the ICAP group are authorised and regulated by the Financial Services Authority. Any investment research sent from ICAP will provide an impartial and objective assessment of the securities, companies or other matters that are the subject of their research and our Conflicts of Interest Management Policy regarding investment research can be viewed by requesting a copy from your usual contact at ICAP. Please visit www.icap.com for further regulatory information including details regarding the European eCommerce Directive. *******************************************************************************" We have taken precautions to minimise the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. " *******************************************************************************

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[Boost.Function] (too) loosly treated argument types
by Slawomir Lisznianski 02 Jan '07

02 Jan '07

Given example below, is there any way to enforce parameter type strictness? [-- Example begin: #include <boost/function.hpp> using namespace boost; // some kind of callback sig. // typedef function1<void, int &> signature; void fn1(int v) // notice arg by-value (say, user typo) { // here, assignments to `v' are lost after // return } void fn2(int & v) // OK { // here, assignments to `v' are // preserved after return } int main(int, char**) { // I want this to fail at compile-time... signature f1 = fn1; // ...and this to work signature f2 = fn2; return 0; } -- code end] On my compiler (g++ (GCC) 4.0.2 20051125) everything compiles fine but ideally, I'd like to fail the first case. Rationale: Users of my library register callbacks and occasionally mistype their function signature which causes them to modify temporaries rather than "out" variables. Thanks, -- Slawomir Lisznianski Paramay Group, LLC "Programs for Research Machinery"

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Re: [Boost-users] fatal error LNK1561: entry point must be definedbuilding boost libs with win32 port of pthread
by Andrew Marlow 02 Jan '07

02 Jan '07

boost-users-bounces(a)lists.boost.org wrote: > "Andrew Marlow" <Andrew.Marlow(a)icap.com> writes: > >> I am trying to build boost using the win32 port of pthreads. It turns out that this is a red herring for the build problem I was having. I get the problem even just using the win32 threads API. > Well, that's interesting; I can think of no reason that the > pthreadwin32 options shouldn't affect anything about the > build of the Regex library. Do you get the same results if > you leave out the -sPTW32_XXX options? Yes, I do :-( >> The CMD file just contains a list of the object files. > > Also interesting; the linker warning claims there were no object > files specified. I agree this is very odd. >> Any ideas please? > > I'm afraid I have no idea. I would probably start by > whittling down the command line issued by bjam until you get > sometihng that seems to be more-or-less correct, so you can identify > what the problem is. I tried downloading and running the boost "exe" from sourceforge. This distribution builds ok with the win32 port of pthreads. I have not diff'd it with the tarball I was using earlier but I suppose there must be differences to get this different behaviour. Very strange. Oh well, at least I have a working boost now. Regards, Andrew Marlow ******************************************************************************" The data and information (collectively called Information) herein is the sole property of ICAP. The Information is confidential, may be legally privileged and is intended solely for the use of the individual or entity to whom it is addressed. Unauthorised disclosure, copying or distribution of the Information is strictly prohibited and the recipient of the Information shall not redistribute the Information in any form to a third party. If you received this Information in error please tell us by reply (or telephone the sender) and delete all copies on your system. References in this Information to ICAP are references to ICAP plc, a company incorporated in England with registered number 3611426 whose registered office is 2 Broadgate, London, EC2M 7UR and where the context requires, includes its subsidiary and associated undertakings. As applicable, certain companies within the ICAP group are authorised and regulated by the Financial Services Authority. Any investment research sent from ICAP will provide an impartial and objective assessment of the securities, companies or other matters that are the subject of their research and our Conflicts of Interest Management Policy regarding investment research can be viewed by requesting a copy from your usual contact at ICAP. Please visit www.icap.com for further regulatory information including details regarding the European eCommerce Directive. *******************************************************************************" We have taken precautions to minimise the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. " *******************************************************************************

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fatal error LNK1561: entry point must be defined building boost libs with win32 port of pthread
by Andrew Marlow 02 Jan '07

02 Jan '07

I am trying to build boost using the win32 port of pthreads. The command I use is: bjam -STOOLS=vc-7_1 -sPTW32_DIR="where-i-put-win32-pthreads" -sPTW32_LIB="pthreadVC.lib" stage The error I get is: LINK : warning LNK4001: no object files specified; libraries used LINK : warning LNK4068: /MACHINE not specified; defaulting to X86 LINK : fatal error LNK1561: entry point must be defined Would be nice of Mico$oft said ***which*** entrypoint is missing. Without that little snippet of information I can only guess.... The log shows the linker command line used: CALL "C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\bin\VCVARS32.BAT" >nul "C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\bin\link" /nologo /INCREMENTAL:NO /LIBPATH:e:\work\overnight\win_extern\lib" /DEBUG /DLL /subsystem:console /out:"..\..\..\bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\t hreading-multi\ boost_regex-vc71-mt-gd-1_33_1.dll" /IMPLIB:"..\..\..\bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debu g\threading-multi\ boost_regex-vc71-mt-gd-1_33_1.lib" @"..\..\..\bin\boost\libs\regex\build\boost_regex.dll\vc-7_1\debug\threa ding-multi\ boost_regex-vc71-mt-gd-1_33_1.CMD" The CMD file just contains a list of the object files. Any ideas please? I am tearing my hair out here. A quick google reveals that a few other people across the world also have this problem, but not many. Those people posted their question to various forums and unfortunately got no reply :-( Regards, Andrew Marlow ---- There is an emerald here the size of a plover's egg! Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html ******************************************************************************" The data and information (collectively called Information) herein is the sole property of ICAP. The Information is confidential, may be legally privileged and is intended solely for the use of the individual or entity to whom it is addressed. Unauthorised disclosure, copying or distribution of the Information is strictly prohibited and the recipient of the Information shall not redistribute the Information in any form to a third party. If you received this Information in error please tell us by reply (or telephone the sender) and delete all copies on your system. References in this Information to ICAP are references to ICAP plc, a company incorporated in England with registered number 3611426 whose registered office is 2 Broadgate, London, EC2M 7UR and where the context requires, includes its subsidiary and associated undertakings. As applicable, certain companies within the ICAP group are authorised and regulated by the Financial Services Authority. Any investment research sent from ICAP will provide an impartial and objective assessment of the securities, companies or other matters that are the subject of their research and our Conflicts of Interest Management Policy regarding investment research can be viewed by requesting a copy from your usual contact at ICAP. Please visit www.icap.com for further regulatory information including details regarding the European eCommerce Directive. *******************************************************************************" We have taken precautions to minimise the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. " *******************************************************************************

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