October 2011 - Boost-users - lists.preview.boost.org

[Objective-C++] Specializing boost::lexical_cast
by Kelvin Chung 16 Oct '11

16 Oct '11

I'm trying to specialize boost::lexical_cast to convert Objective-C objects into various standard C++ classes (for example, leveraging NSNumber::-intValue to create lexical_cast<int>(NSNumber*)). However, as Objective-C objects exist as pointers, I would imagine that they would fail the requirements of needing well-defined streaming operator<<() in order to use the stock boost::lexical_cast. Any words of advice on how to do this in a way that will do as little damage as possible?

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[threadpool] Using with Boost.Bind
by Robert Jones 15 Oct '11

15 Oct '11

Hi All I'm making use of a threadpool implementation from sourceforge, which I know is not properly part of Boost, but I'm hoping someone has some experience which can help me. I'm trying to use one of the functions from pool_adaptors.hpp, which I've reproduced below. I think this contains an error in the first template as the parameter passed as a Pool is used as a pointer to Pool, and I'm guessing there should four functions in here, not three, as the set seems incomplete. On either count I might be missing something. Stripped down my code says approximately this... #include "threadpool.hpp" #include "boost/threadpool/pool_adaptors.hpp" using namespace boost::threadpool; void task( int ); vector<int> v; v += 1,2,3,4,5,6,7,8,9; pool my_pool; for_each( v.begin( ), v.end( ), bind( schedule, my_pool, _1 ) ); ...and of course the problem is that 'schedule' is both templated and overloaded, so the compiler complains it can't find/resolve 'schedule'. The usual solution is to express the exact type of 'schedule' required, but it's huge, and uses types internal the the threadpool library. Is there a better solution? Thanks - Rob. namespace boost { namespace threadpool { // TODO convenience scheduling function /*! Schedules a Runnable for asynchronous execution. A Runnable is an arbitrary class with a run() * member function. This a convenience shorthand for pool->schedule(bind(&Runnable::run, task_object)). * \param * \param obj The Runnable object. The member function run() will be exectued and should not throw execeptions. * \return true, if the task could be scheduled and false otherwise. */ template<typename Pool, typename Runnable> bool schedule(Pool& pool, shared_ptr<Runnable> const & obj) { return pool->schedule(bind(&Runnable::run, obj)); } /*! Schedules a task for asynchronous execution. The task will be executed once only. * \param task The task function object. */ template<typename Pool> typename enable_if < is_void< typename result_of< typename Pool::task_type() >::type >, bool >::type schedule(Pool& pool, typename Pool::task_type const & task) { return pool.schedule(task); } template<typename Pool> typename enable_if < is_void< typename result_of< typename Pool::task_type() >::type >, bool >::type schedule(shared_ptr<Pool> const pool, typename Pool::task_type const & task) { return pool->schedule(task); } } } // namespace boost::threadpool

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Using boost::signal2 for generic event handling with overloaded methods
by Alessandro Giulianelli 15 Oct '11

15 Oct '11

Hi People, I'm studying boost to understand if I can remove from a project a homemade event-dispatcher with boost::signal2 but I found a lot of troubles and I cannot solve it. My actual code which I would migrate to boost is made by a "Sender" and "Multiple Receiver" The sender has the ability to register many "signals" (I use a map for do this" ) and each listener has a map of "slots" connected to the sender of the sender. The sender code is: struct Event {}; struct ID {}; struct OneSecondElapsedEvent : public Event { static ID id; }; struct UpdatePresentationTracksReqEvent : public Event { UpdatePresentationTracksReqEvent() {}; static ID id; }; typedef boost::signals2::signal<void (Event*)> signal_t; typedef signal_t::slot_type slot_t; class MainTask: public Elt::Thread , public Sender { boost::ptr_map<ID*, signal_t> signals_map; public: sig; MainTask(char* taskName); virtual ~MainTask(); void Main(); void registerListener(IListener* listener) { if(listener != NULL) { SlotMap::const_iterator it = listener->slots_map.begin(); for(;it != listener->slots_map.end();it++) { ID *id = it->first; const slot_t *handler = it->second; signals_map[id].connect(*handler); } } else printf("Listener NULLO!!!!\n"); } }; now my generic "listener" or Receiver should be able to register to sender and the code is: #include "SpActiveContext.h" #include <cassert> #include "ActiveObject.h" #include "GenericMessageHandler/ActiveMessage.h" #include "boost/bind.hpp" #include "boost/function.hpp" #include <stdio.h> #include "EventDefinitions.h" #include "MainTask.h" SpActiveContext::SpActiveContext(SpContext * component): _ActiveObject("SpActiveContext"), _Component(component){ assert(_Component); * //boost::function<void (OneSecondElapsedEvent*)> g = boost::bind(&SpActiveContext::Handle, this, _1);* * * * //const slot_t& t = static_cast<void (SpActiveContext::*)(OneSecondElapsedEvent* )>(&SpActiveContext::Handle);* * //registerEvent(OneSecondElapsedEvent::id, t);* * * * //typedef boost::signals2::signal<void (Event*)> signal_t;* * //typedef signal_t::slot_type slot_t;* * * * //boost::bind(&SpActiveContext::Handle(OneSecondElapsedEvent*), this, _1); * * * * //void (SpActiveContext::*Handle) (OneSecondElapsedEvent*) = &SpActiveContext::Handle;* * * * //boost::bind( static_cast<void (SpActiveContext::*)( int )>(&Foo::Bar) , foo, _1);* * * * * * //const slot_t1& t = boost::bind( static_cast<void (SpActiveContext::*)(OneSecondElapsedEvent*)>(&SpActiveContext::Handle) , this, _1);* * //registerEvent(OneSecondElapsedEvent::id, t );* * * * //const slot_t1& t = boost::bind( static_cast<void (SpActiveContext::*)( UpdatePresentationTracksReqEvent *)>(&SpActiveContext::Handle) , this, _1); ** //registerEvent(UpdatePresentationTracksReqEvent ::id, t ); * } void SpActiveContext::Handle(OneSecondElapsedEvent* msg) { printf("OneSecondElapsedEvent 2\n"); } void SpActiveContext::Handle(UpdatePresentationTracksReqEvent* msg) { printf("UpdatePresentationTracksReqEvent\n"); } In the constructor I tried to "connect" the function "Handle(*OneSecondElapsedEvent*)" to the slot but I cannot to this..the compiler write errors sayng that cannot connvert from "Event*" to "OneSecondElapsedEvent*".* * * *Is there any solution to make it working?* * * *Thanks in advance,* *AlexGiul* * *

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serialization basic question
by Luis A. Montes 15 Oct '11

15 Oct '11

Hi, I'm trying to use the serialization library and was having a compile error using MSVC 2005. So I decided to try and compile "A Very Simple Case" from the tutorial, and that of course works. But then I noticed that the example serializes a const object, that sort of is rather useless, so I removed the const specifier, and I got the same error that I was getting with my program, namely: warning C4099: 'boost::serialization::static_warning_impl<false>::STATIC_WARNING' : type name first seen using 'struct' now seen using 'class' I went googling for an answer and I found that I should look at the rationale on the docs, but the rationale (http://www.boost.org/doc/libs/1_47_0/libs/serialization/doc/rationale.html) doesn't seem at all relevant. I finally sort of guessed that I wanted was probably to modify the tracking behavior on my program (looking at the thread http://lists.boost.org/boost-users/2010/05/59107.php ). But my objects are not on the stack, so I'm not really sure. My class structure is a bit more complicated than the simple example, but my question basically is, what changes would be appropriate on the simple example so that it would compile for non-const objects? Thanks

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Boost Object Pool Ticket #3789
by Gokulakannan Somasundaram 15 Oct '11

15 Oct '11

Hi, I just want to know, when the patch will get applied for this bug. We want to use Boost object Pool, but we find this bug very disturbing. Thanks, Gokul.

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[chrono] Compilation with MinGW/gcc 4.4.0
by Richard Hazlewood 14 Oct '11

14 Oct '11

I've been trying to compile the chrono "hello world" example with MinGW/GCC 4.4.0, but it fails. I then tried to compile the tests, and saw similar errors. The docs say this compiler is supported, has anyone else tried this? Here's the error chain: .\boost_1_47_0/boost/type_traits/common_type.hpp: At global scope: .\boost_1_47_0/boost/type_traits/common_type.hpp: In instantiation of 'boost::common_type<double, long long int, long long int>': .\boost_1_47_0/boost/chrono/duration.hpp:252: instantiated from 'ToDuration boost::chrono::detail::duration_cast_aux<FromDuration, ToDuration, Period, true, false>::operator()(const FromDuration&) const [with FromDuration = boost::chrono::duration<long long int, boost::ratio<1ll, 10000000ll> >, ToDuration = boost::chrono::duration<double, boost::ratio<1ll, 1ll> >, Period = boost::ratio<1ll, 10000000ll>]' .\boost_1_47_0/boost/chrono/duration.hpp:311: instantiated from 'ToDuration boost::chrono::detail::duration_cast<FromDuration, ToDuration>::operator() (const FromDuration&) const [with FromDuration = boost::chrono::duration<long long int, boost::ratio<1ll, 10000000ll> >, ToDuration = boost::chrono::duration<double, boost::ratio<1ll, 1ll> >]' .\boost_1_47_0/boost/chrono/duration.hpp:472: instantiated from 'boost::chrono::duration<Rep, Period>::duration(const boost::chrono::duration<Rep2, Period2>&, typename boost::enable_if<boost::mpl::or_<boost::chrono::treat_as_floating_point<Rep>, boost::mpl::and_<boost::chrono::chrono_detail::is_evenly_divisible_by<Period2, Period>, boost::mpl::not_<boost::chrono::treat_as_floating_point<Rep2> >, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> >, mpl_::bool_<false>, mpl_::bool_<false>, mpl_::bool_<false> >, void>::type*) [with Rep2 = long long int, Period2 = boost::ratio<1ll, 10000000ll>, Rep = double, Period = boost::ratio<1ll, 1ll>]' ...\test.cpp:96: instantiated from here .\boost_1_47_0/boost/type_traits/common_type.hpp:77: error: no type named 'type' in 'struct boost::common_type<double, long long int, void>'

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Problem with Spirit Qi and inherited attributes reference
by Anand kumar 14 Oct '11

14 Oct '11

Hello, This is my first time using boost and spirit. I am trying to find construct a tree from a string input. While parsing I am trying to assign each created node a number. For this purpose I am using a inherited attribute, an integer reference. But when I check on the values assigned. It is not the value of the integer reference rather some other value (some consistent value). I am sure this must be something that I am overlooking. But I am not sure what exactly. Thanks for your help, Anand Kumar. Code: struct node; struct term { bool visited; int cnt; int val; term(bool b = false, int cn = -1, int v = numeric_limits<int>::min()) { visited = b; cnt = cn; val = v; } }; BOOST_FUSION_ADAPT_STRUCT( ::term, (bool, visited) (int, cnt) (int, val) ) typedef boost::variant<term, boost::recursive_wrapper<node>> node_impl; struct node { bool visited; int cnt; vector<node_impl> children; }; BOOST_FUSION_ADAPT_STRUCT( ::node, (bool, visited) (int, cnt) (std::vector<::node_impl>, children) ) template<typename Iterator> struct node_parser : qi::grammar<Iterator, node(), ascii::space_type> { qi::rule<Iterator, node(), ascii::space_type> start_r; qi::rule<Iterator, node(int&), ascii::space_type> node_r; qi::rule<Iterator, node_impl(int&), ascii::space_type> node_impl_r; node_parser() : node_parser::base_type(start_r) { using qi::int_; using qi::lexeme; using namespace qi::labels; using phoenix::ref; int cnt = 990; start_r %= node_r(phoenix::ref(cnt)); node_r = ('{' >> +node_impl_r(_r1) >> '}') [at_c<0>(_val) = false, at_c<1>(_val) = _r1++, at_c<2>(_val) = _1]; node_impl_r = ((lexeme['(' >> int_ >> ')'])[_val = phoenix::construct<term>(phoenix::val(false), _r1++, _1)]) | (node_r(_r1)[_val = _1]); } };

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Regarding building of boost1.38.0 with aCC ( Hp compiler)
by Pravar 14 Oct '11

14 Oct '11

Hi *, I am trying to build *boost1.38.0* with *aCC A.0.17* ( HP compiler). I need to understand a few details: - Does in older boost versions, *build process* is a bit different ? I think it is as I can not found any bootstrap.sh in boost root directory. - Does $BOOST_ROOT./configure is equivalent to $BOOST_ROOT./bootstrap.sh in latest versions ? I executed following commands during building of boost 1.38.0 : - From boost root directory, ./configure --prefix=/opt/boost, I get following output, ----------------------------------------------------------------------- -n Building Boost.Jam with toolset acc... tools/jam/src/bin.hpuxia64/bjam ----------------------------------------------------------------------- - Then, I changed directory to tools/jam/src/bin.hpuxia64/bjam. I tried to build by executing ./bjam /some build options/ I get below error, *------------------------------------------------------- notice: could not find main target install notice: assuming it is a name of file to create. don't know how to make <e>install ...found 1 target... ...can't find 1 target... --------------------------------------------------------* Is there something i am missing ? Any inputs would be helpful. Best Regards, Pravar DISCLAIMER: ----------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or NECHCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of NECHCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. . -----------------------------------------------------------------------------------------------------------------------

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[thread] UpgradeLockable Concept & Writer Starvation
by Ovanes Markarian 14 Oct '11

14 Oct '11

Hello *, I was reading through the docs of boost::thread lib and I can't find any guarantees that when using upgrade_lock the writer (upgrader) starvation is prevented. Are there any ordering guarantees, that if some thread is going to upgrade the lock the threads which acquire the shared lock after the upgrade request will not be able to acquire the lock until the upgrade request was accomplished and released the lock? Many thanks for help, Ovanes

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Problem using special mathematical function in Visual C++
by Keith Fraser 13 Oct '11

13 Oct '11

Hello, I downloaded Boost in order to use the expint function: http://www.boost.org/doc/libs/1_37_0/libs/math/doc/sf_and_dist/html/math_to… I copied the /boost folder into the /include folder in Visual C++ where the other library files (stdio.h, etc.) are kept. In the .cpp file for the program I wanted to use expint in, I inserted the following line, taken from the description: #include <boost/math/special_functions/expint.hpp> When compiling, Visual C++ appears to be able to open expint.hpp, but it doesn't recognize the function: error C3861: 'expint': identifier not found Is there something else I need to add to the .cpp file so that expint will be recognized? I am using Visual C++ 2010 Express. Thanks, Keith

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