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[unit test] problem inside boost UTF
by Bruno Belarte 05 Apr '11

05 Apr '11

Hi, I'm new with boost, and I'm actually experiencing some weird issues... I wrote a class which is basically a wrapper around boost::adjacency_list, and two other nested classes which are wrappers around boost::adjacency_list::vertex_iterator and boost::adjacency_list::out_edge_iterator. I tested theses three classes with the boost unit test framework : everything works fine. Then I wrote a class Tree, which uses boost::shared_/weak_ptr. But when I try to test this class with boost UTF, the test case of the previous graph's out_edge_iterator returns some failures (different depending of the functions from the Tree class called on the test). It's particularly weird considering that these classes share nothing in common except the fact that they use different part of boost. Maybe somebody have a hint on what I am doing wrong !? I used UTF with dynamic lininking, boost1.42 from ubuntu 10.10 package. Thanks, Bruno

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[threads] Deadlock?
by The Novice Coder 05 Apr '11

05 Apr '11

I'm working with boost:threads, and am having what appears to be a deadlock issue. I'm not sure if the lock is something I'm doing, or if it's my lack of understanding of boost::condition_variable. The code deadlocks on this snippit: if( wait) { // lock the condition, add the event, wait for the condition, and get the return value! boost::mutex::scoped_lock lk(serviceMutex_); clearException(); returnValue_ = 0; qApp->postEvent(temp_this, temp_event, Qt::HighEventPriority); serviceCondition_.wait(lk); } Where wait is specified by the caller to wait for the other thread to return. In the service request thread has this snippet: { boost::mutex::scoped_lock lk( serviceMutex_); returnValue_ = qtService(s->getCommand()); serviceCondition_.notify_one(); } I tried it with and without the lock (in the 2nd snippet) but the 2nd snippet code is never getting called and just seems to vanish when wait is specified. When wait isn't specified, it all works. (Non-wait is just the same thing without any of the locks/conditions.) Any thoughts on where to look to proceed or what documents to read ? Thanks, and apologies for the inexperience. New to boost..

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Search and replace in text files with Boost.Xpressive
by Júlio Hoffimann 04 Apr '11

04 Apr '11

What is the better approach with Boost to catch a file with some wildcard-prefixed variables and replace them by numerical values? Example: $ cat file.tmpl ============ var1 = $something ... ... $coord1 $coord2 ... $coordN ... ... ============ $ cat file.dat ============ var1 = 2.35323 ... ... 1.4 3.5 124 910 ... ... ============ The Boost libraries i know for regular expressions are Boost.Regex and Boost.Xpressive. I like the second, because it's header only, has static and dynamic regular expressions and uses it's own namespace. In other words, it incorporates the features of Boost.Regex in a more elegant way. As far as i know, Boost.Xpressive treats only std::string and C-like strings. What i need to do for work with text files? Put them inside a std::string? About the performance, the files has approximately 10^3 lines, the search and replace will be an issue? Regards, Júlio.

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Using boost::shared_ptr with std::set
by przemyslaw.sliwa＠uk.bnpparibas.com 04 Apr '11

04 Apr '11

Hello, I have to use a set of shared pointers to objects. The struct I have to use looks like struct eventIntLim { enum eType { eStart = 0, eEnd }; eType type; double varianceBump; eventIntLim(eType t, double v) : type(t), varianceBump(v) {} bool operator < (const eventIntLim &rhs) const { return fabs(varianceBump) < fabs(rhs.varianceBump); } }; and the definition of the set is typedef boost::shared_ptr<eventIntLim> eventIntLimPtr; typedef std::set<eventIntLimPtr, lessThan> eventIntLimPtrSet; typedef std::map<size_t, eventIntLimPtrSet> eventIntLimMap; In order to sort the objects in the set I have to use the functor struct lessThan : public std::binary_function<boost::shared_ptr<eventIntLim>, boost::shared_ptr<eventIntLim>, bool> { bool operator ()(const boost::shared_ptr<eventIntLim> &lhs, const boost::shared_ptr<eventIntLim> &rhs) const { return (*lhs) < (*rhs); } }; This is quite long and I believe boost can shorten it a lot. I have tried it with boost::lamba and boost::bind but could not make it working. Basically I would like to eliminate the need of writing the definition of struct lessThan. Could someone help me with that? Cheers ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/information/legal_information.asp?Code=ECAS-… for additional disclosures.

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[MPL] initialization of member that might be non-copyable
by Noah Roberts 04 Apr '11

04 Apr '11

I'm working on something similar to the construct devised in the MPL book Section 9.5 (class composition). Some objects in the composed type might require initialization. I've solved this problem. However, in solving that problem I've now required that any type going into the composition must be copyable. However, since the original composition code doesn't make this requirement I've been trying to find a way to retain the ability to contain types that are non-copyable. Here's some code: template < typename Field > struct field_value { typedef Field field; typedef typename Field::type ftype; ftype value; field_value(ftype const& t) : value(t) {} field_value() : value() {} }; template < typename Field, typename ParamFields, typename Enable = void > struct initializer { template < typename Params > static typename Field::type apply(Params &) { return Field::type(); } }; template < typename Field, typename ParamFields > struct initializer<Field,ParamFields, typename boost::enable_if< boost::mpl::contains<typename Params::fields, typename FieldValue::field> >::type > { template < typename Params > static typename Field::type apply(Params & params) { return get<Field>(params); } }; template < typename FieldValue, typename Params > FieldValue init_field(Params & pars) { return initializer<typename FieldValue::field, typename Params::fields >::apply(pars); } template < typename FieldValue, typename More > struct record_base : FieldValue, More { template < typename Params > record_base(Params & pars) : FieldValue(init_field<FieldValue>(pars)) , More(pars) {} record_base() : FieldValue(), More() {} }; struct empty_record_base { template < typename Ignored > empty_record_base(Ignored&){} empty_record_base() {} }; template < typename MplSequence > struct build_record { typedef boost::mpl::placeholders::_1 _1; typedef boost::mpl::placeholders::_2 _2; typedef typename boost::mpl::fold < MplSequence , empty_record_base , record_base< field_value<_2>, _1 > >::type type; // type should be record_base< field_value<field0> // , record_base< field_value<field1> // , ... record_base<field_value<fieldN>, empty_record_base> // > ... // > }; It's at this point: template < typename Params > record_base(Params & pars) : FieldValue(init_field<FieldValue>(pars)) , More(pars) {} That I need to apply something, I know not what, to correctly initialize the field with either a parameter argument or nothing. I can't think of any construct that would make that possible but I don't necessarily know everything. Is there some way that this can be accomplished?

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[phoenix] lazy function to reference or const reference
by alfC 04 Apr '11

04 Apr '11

Hi, Is it possible to use references as the type of the function wrapped by lazy function. The reason I need this is because I need to instatiate a lazy function inside a class and to a class while the class does not have yet a complete definition. The application may sound exotic but I see no intrinsic limitation why the following doesn't work. If this is not possible because an intrinsic limitation of phoenix, is there a workaround? -- Thanks -- Alfredo ... is_odd_impl is defined as in http://svn.boost.org/svn/boost/sandbox/SOC/2010/phoenix3/libs/phoenix/doc/h… #include<iostream> #include<boost/phoenix/core.hpp> #include<boost/phoenix/function.hpp> using namespace std; using boost::phoenix::arg_names::arg1; int main(){ int cuatro = 4.; is_odd_impl ioi; clog << ioi(cuatro) << endl; boost::phoenix::function<is_odd_impl> fioi; clog << fioi(arg1)(cuatro) << endl; boost::phoenix::function<is_odd_impl&> fioi_ref(ioi); clog << fioi_ref(arg1)(cuatro) << endl; //doesn't compile !!! boost::phoenix::function<is_odd_impl const&> fioi_cref(ioi); clog << fioi_cref(arg1)(cuatro) << endl; //doesn't compile !!! return 0; } example error message: usr/include/boost/phoenix/core/preprocessed/expression_10.hpp:101:17: error: invalid initialization of reference of type ‘const is_odd_impl&’ from expression of type ‘const boost::proto::result_of::make_expr<boost::proto::tag::function, boost::phoenix::default_domain_with_basic_expr, const is_odd_impl, const boost::phoenix::actor<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::argument<1> >, 0l> >, void, void, void, void, void, void, void, void, void, void>::type’

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[Thread] Strange problem.
by Germán Diago 04 Apr '11

04 Apr '11

Hello. I'm designing a class with a locking policy. I have some code that does exaclty this: if (cond) { locking_policy_.lock(); out << message.message(); locking_policy_.unlock(); } return *this; And the lockingpolicy is a class like this one: struct ThreadSafe { boost::mutex io_mutex_; boost::unique_lock<boost::mutex> lock_; ThreadSafe() : io_mutex_(), lock_(io_mutex_, boost::defer_lock) {} void lock() { std::cout << "Locking from " << boost::this_thread::get_id() << std::endl; lock_.lock(); } void unlock() { std::cout << "Unlocking from " << boost::this_thread::get_id() << std::endl; lock_.unlock(); } }; Then, I create 3 threads and join them in the same order I created them: boost::thread t1(&doSomething, "Hello1", boost::ref(logsink)); boost::thread t2(&doSomething, "Hello2", boost::ref(logsink)); boost::thread t3(&doSomehting, "Hello3", boost::ref(logsink)); t1.join(); t2.join(); t3.join(); and I get a lock_error. Any help here, please? I can't figure out the problem.

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[asio] port question
by Pace, Antony [Harman Pro Group UK] 04 Apr '11

04 Apr '11

I would like to use boost::asio on my unusual platform which supports Berkeley sockets and has an RTOS and I have full control of low level interrupts etc. I have seen socket_types.hpp and feel that it is likely that I could find a set of defines that match my stack. I also have a timer interrupt that I imagine could be fed into the asio timer somehow but wonder if anyone could tell me how much work I am letting myself in for with that approach or if I would be better off using the Berkeley sockets directly? Many thanks Ant [cid:image001.png@01CBF081.1EA6DAD0] Cranborne House, Cranborne Road, Potters Bar, Herts, EN6 3JN Phone: +44 1707 668025 Email: antony.pace(a)harman.com Skype: antony.pace.harman Web: www.harman.com ANTONY PACE Senior Software Engineer Soundcraft Studer R&D Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorised review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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[boost::mutex] Suspicious EINVAL error
by Panagiotis Foteinos 03 Apr '11

03 Apr '11

Hello users. I am running a single thread which locks and unlocks mutexes, and I get the following error: * /usr/include/boost/thread/pthread/mutex.hpp:55: void boost::mutex::lock(): Assertion `!pthread_mutex_lock(&m)' failed, *after a boost::shared_mutex::lock() or a boost::shared_mutex::try_lock(). In fact, I checked the error code that pthread_mutex_lock(&m) returned and it was the EINVAL error (code number 22). The posix manual gives 2 possibilities for this error: 1) the mutex has not been properly initialized, or 2) The *mutex* was created with the protocol attribute having the value PTHREAD_PRIO_PROTECT and the calling thread's priority is higher than the mutex's current priority ceiling. Sadly, the mutex is correctly initialized. As far as possibility (2) is concerned, well I cannot interpret it... My code is pretty big, so I cannot provide a complete snippet, but roughly (just in case it helps): **************************************************************************************************** I have the following class: class Vertex { boost::shared_mutex mtx; Vertex() {} }; whose objects call Vertex::mtx->lock(), Vertex::mtx->unlock(), Vertex::mtx->lock_shared(), and Vertex::mtx->unlock_shared(). The above error is produced whenever a specific object (residing in memory) locks or even try_locks its mutex. It always happens for a specific object. **************************************************************************************************** I am using the GNU C++ compiler 4.4.3 on Ubuntu x86_64. I do realize that the information I provide in this email is little, but I, being new in boost::mutexes and having spent so much time on it, decided to give it a shot. Best Regards, Panagiotis Foteinos

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Copy-on-write STL containers
by Alexandr Sterligov 03 Apr '11

03 Apr '11

Is there any interest in a library of STL-compilant containers (vector, deque, map, set, list) with copy-on-write? -- Best regards, Alexander Sterligov

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