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

[boost::condition_variable_any] Telling cond to unlock_share()
by Panagiotis Foteinos 28 Mar '11

28 Mar '11

Hello users. Documentation says that cond.wait(mtx) blocks the current thread and invokes mtx.unlock(). What if I want cond.wait(mtx) to call mtx.unlock_shared() instead? Is there any way to do so? Regards, Panagiotis Foteinos

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OT: Why can't I insert a vector of int
by Patrick Horgan 28 Mar '11

28 Mar '11

I simplified this as much as possible and it turned into a template question, and not a boost question, but I hope that someone here will take a second and answer it anyway. I don't know of another mailing list with the expertise of this one in templates. In the below, the inserter for vector<int> is never used, instead, since the vector<int> is a type, it matches the simpler inserter for T. How can I make it work the way I want it to? #include <iostream> #include <vector> struct theclass { template<typename T> void operator<<(const T& t){ std::cout << "Got a T\n"; } template<typename T> void operator<<(std::vector<const T> t){ std::cout << "Got a vector of T\n"; } }; int main() { std::vector<int> vi; int i; theclass f; f << i; f << vi; }

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Re: [Boost-users] Regex question: is this a bug or a feature?
by Jerry 28 Mar '11

28 Mar '11

Kulti <kultihell <at> gmail.com> writes: > Ramon F Herrera <ramon <at> patriot.net> wrote: > > My pattern matching was failing when I had these definitions, > > which I happen to prefer: > > > > const string number = "[0-9]+"; > > const string name = "[A-z][A-z0-9]*"; > > > > The program is working fine now, after I am using these ones: > > > > const string number = "\\d+"; > > const string name = "[A-z]\\w*"; > > > > Could you please read documentation before posting question? > http://www.boost.org/doc/libs/1_45_0/libs/regex/doc/html/boost_regex/syntax… racter_classes/std_char_clases.html > "w - Any word character (alphanumeric characters plus the underscore)" > Actually I don't think he was asking why w included underscores - I think he was asking why that worked and his original character class based regex didn't. Jerry

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Boost::Polygon issue with including in project
by Chris Stylianou 28 Mar '11

28 Mar '11

I'm having an issue trying to use Boost::Polygon, I've added boost/polygon/polygon.hpp but when I try to compile I get: boost/polygon/transform.hpp:147: error: expected identifier before numeric constant boost/polygon/transform.hpp:147: error: expected `}' before numeric constant boost/polygon/transform.hpp:147: error: expected unqualified-id before numeric constant boost/polygon/transform.hpp:219: error: expected unqualified-id before ')' token boost/polygon/transform.hpp:220: error: expected `)' before 'atr' boost/polygon/transform.hpp:221: error: expected unqualified-id before 'const' boost/polygon/transform.hpp:221: error: expected `)' before 'const' boost/polygon/transform.hpp:222: error: expected unqualified-id before 'const' boost/polygon/transform.hpp:222: error: expected `)' before 'const' boost/polygon/transform.hpp:223: error: expected unqualified-id before 'const' boost/polygon/transform.hpp:223: error: expected `)' before 'const' boost/polygon/transform.hpp:224: error: expected unqualified-id before 'const' boost/polygon/transform.hpp:224: error: expected `)' before 'const' boost/polygon/transform.hpp:225: error: expected unqualified-id before 'const' boost/polygon/transform.hpp:225: error: expected `)' before 'const' boost/polygon/transform.hpp:228: error: 'boost::polygon::axis_transformation& boost::polygon::operator=(const boost::polygon::axis_transformation&)' must be a nonstatic member function boost/polygon/transform.hpp:231: error: expected ',' or '...' before '&' token boost/polygon/transform.hpp:231: error: 'boost::polygon::axis_transformation& boost::polygon::operator=(int)' must be a nonstatic member function boost/polygon/transform.hpp:234: error: non-member function 'bool boost::polygon::operator==(const boost::polygon::axis_transformation&)' cannot have cv-qualifier boost/polygon/transform.hpp:234: error: 'bool boost::polygon::operator==(const boost::polygon::axis_transformation&)' must take exactly two arguments boost/polygon/transform.hpp:237: error: non-member function 'bool boost::polygon::operator!=(const boost::polygon::axis_transformation&)' cannot have cv-qualifier boost/polygon/transform.hpp:237: error: 'bool boost::polygon::operator!=(const boost::polygon::axis_transformation&)' must take exactly two arguments boost/polygon/transform.hpp:240: error: non-member function 'bool boost::polygon::operator<(const boost::polygon::axis_transformation&)' cannot have cv-qualifier boost/polygon/transform.hpp:240: error: 'bool boost::polygon::operator<(const boost::polygon::axis_transformation&)' must take exactly two arguments boost/polygon/transform.hpp:243: error: non-member function 'boost::polygon::axis_transformation boost::polygon::operator+(const boost::polygon::axis_transformation&)' cannot have cv-qualifier boost/polygon/transform.hpp:246: error: 'boost::polygon::axis_transformation& boost::polygon::operator+=(const boost::polygon::axis_transformation&)' must take exactly two arguments boost/polygon/transform.hpp:250: error: non-member function 'void boost::polygon::populate_axis_array(boost::polygon::INDIVIDUAL_AXIS*)' cannot have cv-qualifier boost/polygon/transform.hpp:255: error: non-member function 'void boost::polygon::get_directions(boost::polygon::direction_2d&, boost::polygon::direction_2d&)' cannot have cv-qualifier boost/polygon/transform.hpp: In function 'void boost::polygon::get_directions(boost::polygon::direction_2d&, boost::polygon::direction_2d&)': ........etc ....... Thanks Chris

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Re: [Boost-users] lambda - if_then_else - Compiler can not deduce my Arguments
by Simon Adler 28 Mar '11

28 Mar '11

Hey Thomas > On Mon, Mar 28, 2011 at 11:16 AM, Thomas Heller < > thom.heller(a)googlemail.com> wrote: > >> On Monday, March 28, 2011 11:34:45 AM Simon Adler wrote: >> >> > class XML_Element >> > { >> > public: >> > const std::string & getName(void); >> > }; >> > >> > class HandleStuff >> > { >> > void handleTransformations( XML_Element * node ); >> > void handleLinks( XML_Element * node ); >> > >> > >> > void handle ( std::list<XML_Element *> * nodes ) >> > { >> > // what i want to do via boost and which will do the job >> > for (std::list< XML_Element *>::iterator it = nodes->begin(); it != >> > nodes->end(); it++) >> > { >> > if ( (*it)->getName() == "Transform" ) handleTransformations(*it); >> > else handleLinks(*it); >> > } >> > >> > // what i tried >> > std::for_each( nodes->begin(); nodes->end(), >> > boost::lambda::if_then_else( boost::bind(&XML_Element::getName, _1) >> == >> > std::string("Transform"), >> > >> > boost::bind<void>(&HandleStuff::loadTransformations, this, _1), >> > >> > boost::bind<void>(&HandleStuff::loadLinks, this, _1) ) >> > } >> > >> > } >> >> The error you made is that you mixed boost bind with lambda, which is not >> compatible. >> >> A solution with Phoenix looks like this: >> >> using boost::phoenix::arg_names::_1; >> using boost::phoenix::bind; >> using boost::phoenix::if_; >> >> std::for_each( nodes->begin(), nodes->end(), >> if_(bind(&XML_Element::getName, _1) == "Transform") >> [ >> bind(&HandleStuff::handleTransformations, this, _1) >> ] >> .else_ >> [ >> bind(&HandleStuff::handleLinks, this, _1) >> ] >> ); >> > Yes, it worked. I did not know Phoenix and included now boost/spirit/include/phoenix.hpp - quite big during compilation. It solved my Problem, but if this is a type missmatch - how can i solve this without Phoenix. I have to understand what is going on. I tried to solve this with explicit namespace declarations and replaced _1 via boost::lambda::_1 I also tried to replace all with ::_1 which should explicitly take the declarations from bind/placeholders.hpp thouse are in an unnamed namespace. Please - how can I solve this without using Phoenix? - Not that i don't like your solution but i will understand. Simon

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lambda - if_then_else - Compiler can not deduce my Arguments
by Simon Adler 28 Mar '11

28 Mar '11

Hello, i need a hint about boost::bind and lambda. Following (reduced) case: class XML_Element { public: const std::string & getName(void); }; class HandleStuff { void handleTransformations( XML_Element * node ); void handleLinks( XML_Element * node ); void handle ( std::list<XML_Element *> * nodes ) { // what i want to do via boost and which will do the job for (std::list< XML_Element *>::iterator it = nodes->begin(); it != nodes->end(); it++) { if ( (*it)->getName() == "Transform" ) handleTransformations(*it); else handleLinks(*it); } // what i tried std::for_each( nodes->begin(); nodes->end(), boost::lambda::if_then_else( boost::bind(&XML_Element::getName, _1) == std::string("Transform"), boost::bind<void>(&HandleStuff::loadTransformations, this, _1), boost::bind<void>(&HandleStuff::loadLinks, this, _1) ) } } got an error, that the compiler can not deduce a template Argument, but i do not understand what the compiler tries to say. I am new to bind and lambda and i like it a lot, but in some cases the Error-Messages are hard to understand. Thank you for any advice. Please understand, that this example is a reduced Version what is realy going on, so i only give the Functions Interfaces. Simon

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Regex question: is this a bug or a feature?
by Ramon F Herrera 28 Mar '11

28 Mar '11

My pattern matching was failing when I had these definitions, which I happen to prefer: const string number = "[0-9]+"; const string name = "[A-z][A-z0-9]*"; ("name" is supposed to match a typical variable name) The program is working fine now, after I am using these ones: const string number = "\\d+"; const string name = "[A-z]\\w*"; The only difference that I aware of, is that the second form accepts underscores as part of variable names. TIA, -RFH

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[test]
by Stirling Westrup 28 Mar '11

28 Mar '11

I have been using Boost.test to run some simple unit tests as I build my code. I've come across a case where I need to test if my code runs within an acceptable time limit. I know that the execution monitor has a timeout system for testing that sort of thing, but I can't figure out how it is supposed to be integrated into the unit test framework. Ideally, I'd love to just have a BOOST_CHECK_TIMED( f(), timeout) that I could invoke to ensure that the code returns true, and returns within the specified timeout interval. -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com http://sourceforge.net/users/stirlingwestrup

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[boost::shared_ptr] Memory is not freed
by Panagiotis Foteinos 28 Mar '11

28 Mar '11

Hello users. In the past, I wrote a program using the C++ built-in pointers. I made sure that there was not any memory leak: indeed, valgrind reported no memory leaks. I decided to switch to boost::shared_ptr, and replaced all the C++ built-in pointers with boost:shared_ptr ones. Interestingly, valgrind now reports a huge memory leak. I thought that by just replacing the built-in pointers with the boost::shared_ptr pointers (forgetting about explicit deletes of memory) would be enough. Note that I use boost::make_shared<> for memory allocations. I wish I could include the code in this email, but it is very long and complicated. Therefore, I am kindly asking you to guess what might have been wrong with the boost:shared_ptr. Could you think of any scenarios that would cause the observed bahavior? Any ideas would be welcome. OS: Ubuntu 64 Compiler: gcc version 4.4.3 Best Regards, Panagiotis Foteinos

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[serialization] empty xml output
by Olivier Tournaire 27 Mar '11

27 Mar '11

Hi all, I am trying to introduce XML serialization in my project, but even with the simplest test, I cannot get something to work. Here is what I did: #define PARAMETERS_HPP #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <iostream> class rss_feeds_to_parse { public: bool all; template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { ar & BOOST_SERIALIZATION_NVP(all); } }; class parameters { public: rss_feeds_to_parse feeds; template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { ar & BOOST_SERIALIZATION_NVP(feeds); } }; #endif // PARAMETERS_HPP Later, in my main, I have: parameters p; p.feeds.all = true; std::ofstream ofs("test_parameters.xml"); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(p); It compiles, links and executes well, the file test_parameters.xml is created ... but empty ! What am I doing wrong? Hope you could help. Best regards, Olivier

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