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Re: [Boost-users] How to manually lock and unlock a mutex?
by Sohail Somani 29 Jul '05

29 Jul '05

You're not supposed to know about detail... :D > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Christian Henning > Sent: Friday, July 29, 2005 11:29 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] How to manually lock and unlock a mutex? > > > Seems to me that I should take a look at the detail folder in > the thread lib. ;-) > > Thanks you all for helpful suggestions, > Christian > > On 7/29/05, Sohail Somani <s.somani(a)fincad.com> wrote: > > scoped_ptr would be more appropriate I think. > > > > > -----Original Message----- > > > From: boost-users-bounces(a)lists.boost.org > > > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Jason > > > Stewart > > > Sent: Friday, July 29, 2005 10:01 AM > > > To: boost-users(a)lists.boost.org > > > Subject: Re: [Boost-users] How to manually lock and > unlock a mutex? > > > > > > > > > Try > > > > > > void foo() > > > { > > > shared_ptr<scoped_lock> lk; > > > if (condition) > > > lk.reset(new scoped_lock(mutex)); > > > > > > do something > > > } > > > > > > The smart pointer will automatically unlock when it goes out of > > > scope. > > > > > > _______________________________________________ > > > Boost-users mailing list > > > Boost-users(a)lists.boost.org > > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > > > > > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > > > _______________________________________________ > 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] How to manually lock and unlock a mutex?
by Sohail Somani 29 Jul '05

29 Jul '05

scoped_ptr would be more appropriate I think. > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Jason Stewart > Sent: Friday, July 29, 2005 10:01 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] How to manually lock and unlock a mutex? > > > Try > > void foo() > { > shared_ptr<scoped_lock> lk; > if (condition) > lk.reset(new scoped_lock(mutex)); > > do something > } > > The smart pointer will automatically unlock when it goes out of scope. > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users >

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shared_array EXC_BAD_ACCESS
by Christopher Hunt 29 Jul '05

29 Jul '05

Hi there, I'm attempting to use a shared_array as member of a class that I have. Something akin to the following: class UTFStringHolder { ... boost::shared_array<unsigned short> mStrBufferP; }; When UTFStringHolder is instantiated, I get an EXC_BAD_ACCESS and my stack trace shows that pthread_mutex_init is being called. Here's the complete stack trace: #0 0x90012730 in _pthread_mutex_init #1 0x00088424 in boost::detail::lightweight_mutex::lightweight_mutex() at lwm_pthreads.hpp:47 #2 0x00088024 in boost::detail::lightweight_mutex::lightweight_mutex() at lwm_pthreads.hpp:49 #3 0x00087bc4 in boost::detail::sp_counted_base::sp_counted_base() at shared_count.hpp:98 #4 0x00086614 in boost::detail::sp_counted_base::sp_counted_base() at shared_count.hpp:99 #5 0x00098be0 in boost::detail::sp_counted_base_impl<unsigned short*, boost::checked_array_deleter<unsigned short> >::sp_counted_base_impl(unsigned short*, boost::checked_array_deleter<unsigned short>) at shared_count.hpp:253 #6 0x00098b8c in boost::detail::sp_counted_base_impl<unsigned short*, boost::checked_array_deleter<unsigned short> >::sp_counted_base_impl(unsigned short*, boost::checked_array_deleter<unsigned short>) at shared_count.hpp:253 #7 0x00098ac4 in boost::detail::shared_count::shared_count<unsigned short*, boost::checked_array_deleter<unsigned short> >(unsigned short*, boost::checked_array_deleter<unsigned short>) at shared_count.hpp:340 #8 0x00098a48 in boost::detail::shared_count::shared_count<unsigned short*, boost::checked_array_deleter<unsigned short> >(unsigned short*, boost::checked_array_deleter<unsigned short>) at shared_count.hpp:345 #9 0x00098900 in boost::shared_array<unsigned short>::shared_array(unsigned short*) at shared_array.hpp:57 #10 0x0009889c in boost::shared_array<unsigned short>::shared_array(unsigned short*) at shared_array.hpp:57 #11 0x00029f34 in Classee::UTFStringHolder::UTFStringHolder() at UTFString.cpp:20 Any ideas/pointers? I'm using boost v.1.32. Thanks for any help as I'm going bonkers. :-P Cheers, -C

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How to manually lock and unlock a mutex?
by Christian Henning 29 Jul '05

29 Jul '05

Hi there, I'm converting over our codebase to make use of the boost libs. Is there a way to manually lock and unlock a boost:mutex? Or, is there a conditional lock available? I know there is boost::mutex::scoped_lock that does it automatically. Here is code example that, I think, requires manual locking: void foo() { if( condition ) oMutex.lock; do something if( condition ) oMutex.unlock; } It might be that our code isn't designed very well for using boost::mutex. One solution would be: void foo() { if( condition ) { boost::mutex::scoped oLock( oMutex ); do something } else { do something } } Thanks, Christian

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questions concerning optional + date_time + serialize
by Jasper, Alexander 29 Jul '05

29 Jul '05

Hi All! I've got few questions concerning the date_time, optional and serialization libs (1.32) and how they work together. I'm trying to serialize a optional<posix_time::time_duration> using a binary Archive. Unfortunately the extraction code fails to compile. This is because the optional<T> requires T to have a default constructor, when extraction from an archive (see code take from optional.hpp below). I changed the code ( see blow) to work around this. I know that is neither efficient (heap usage) nor exception safe but it works for me. Also it requires operator=. But ptime has got this. Does any body have more advanced suggestions to solve this? Another thing is that I'm unable to serialize not_a_date_time ptimes. The extractions fails here. I'm using the binary archive. Is that supported? The documentation of date time only states compatibility with text and XML archive... Any hints are greatly appreciated and thanks in advance. kind regards Alex template<class Archive, class T> void save( Archive & ar, const boost::optional<T> & t, const unsigned int /*version*/ ){ bool tflag = t; ar << boost::serialization::make_nvp("initialized", tflag); if (tflag) //ar << boost::serialization::make_nvp("value", &(*t)); ar << &(*t); } template<class Archive, class T> void load( Archive & ar, boost::optional<T> & t, const unsigned int /*version*/ ){ bool tflag; ar >> boost::serialization::make_nvp("initialized", tflag); if (tflag){ T* p; ar >> p;// boost::serialization::make_nvp("value", p); t.reset(*p); //T aux; //ar >> boost::serialization::make_nvp("value", aux); //t.reset(aux); delete p; } else { t.reset(); } }

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Re: [Boost-users] Test Tools Linking Problem
by Merrill Cornish 29 Jul '05

29 Jul '05

John, <sound of head banging on the keyboard> Yes, I knew the order was important, but I remembered the wrong order. :-( Thanks, Merrill

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Re: [Boost-users] Test Tools Linking Problem
by Merrill Cornish 29 Jul '05

29 Jul '05

Gennadiy, I re-built the libs just as you said. I then copied the newly built static library to the stage/lib directory where I have all of the others. Unfortunately, I still got the same undefined. HOWEVER!... This is the first time I've noticed the boost_1_32_0/bin directory. I tried copying test_tools.obj into the directory with my own object files, added test_tools.obj to the list of my own object files in my make, and the link WORKED! To me, that says the Boost code if OK, but I've messed up makefile. (It's been many years since I've had to do battle with a raw makefile, and it wasn't GCC's make then.) I've appended an excerpt from my makefile. The "test" target is the one that gets the undefined referenced UNLESS test_tools.obj is included in the ${testobjs} list. (Yes, there is a TAB before ${CXX}.) What's wrong with the makefile? Merrill ---------------------------------------------------------------- basedir = E:/DigS boostdir = E:/boost_1_32_0 boostlibdir = ${boostdir}/stage/lib boostlibtype = -mgw-mt-1_32 boostlibs = ${boostlibdir}/boost_regex${boostlibtype}.dll boosttestlibs = ${boostlibdir}/libboost_unit_test_framework${boostlibtype}.lib . . . test : ${testobjs} ${CXX} -o test ${boosttestlibs} ${boostlibs} test.o ${testobjs}

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bosst::bind problem
by Oleg Smolsky 28 Jul '05

28 Jul '05

Hi all, I've just started using boost::bind and found the following problem: class Handler { public: bool Test1(std::string sComponent); bool Test2(std::string sComponent, std::string sAddress); }; void Test() { std::vector<Handler> v; // This compiles std::string a, b; std::for_each(v.begin(), v.end(), boost::bind(&Handler::Test1, _1, a)); // This doesn't compile //std::for_each(v.begin(), v.end(), // boost::bind(&Handler::Test2, _1, _2, a, b)); } Environment: boost 1.32, VC8, WinXP. Any ideas? Thanks, Oleg.

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Branch and Bound alogorithm
by Abhijit Deshmukh 28 Jul '05

28 Jul '05

Hi everyone, I'm a new user of BGL. So can anyone please tell me whether any direct Branch and Bound algorithm is already implemented in BGL? I haven't been able to find any. Basically I have to modify DFS using branch and bound scheme to avoid unnecessary computations. I think that the DFS Visitor interface can be used to do that. Is this the best way to proceed? Thanks in advance, with regards, Abhijit

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[Boost Lambda] Simple problem using argument as object: part III
by Thaddeus Olczyk 28 Jul '05

28 Jul '05

Ok. I'm still not getting it. Sorry for the inconvenience. Another piece of sample code that doesn't compile. Thanks. #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/if.hpp> #include <vector> #include <set> #include <string> #include <iostream> using boost::lambda::_1; using boost::lambda::bind; class A { std::string s; public: A(std::string sIn):s(sIn){} void print_A() { std::cout<<"A="<<s<<std::endl; } bool isLong() { return s.length()>5; } std::string get(){return s;} }; typedef std::vector<A *> AList; typedef std::set<std::string> StrList; int main() { std::string in; AList alist; StrList excluded; while(in!="end") { in=""; std::getline(std::cin,in); alist.push_back(new A(in)); } std::for_each(alist.begin(),alist.end(), boost::lambda::if_then((bind(&StrList::find,&excluded,bind(&A::get,_1))) !=excluded.end()), bind(&StrList::insert,&excluded,bind(&A::get,_1))); std::for_each(alist.begin(),alist.end(), bind(&A::print_A,_1)); return 1; } ----------------------------------- main2.cpp:43: error: no matching function for call to `bind(<unknown type>, StrList*, const boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<std::string (A::*const)(), const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >)' main2.cpp:45: error: no matching function for call to `bind(<unknown type>, StrList*, const boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<2, boost::lambda::function_action<2, boost::lambda::detail::unspecified> >, boost::tuples::tuple<std::string (A::*const)(), const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >)' -- Thad

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