December 2009 - Boost-users - lists.preview.boost.org

[Fwd: boost::bind vs. boost::lambda::bind - bug]
by Chris Hite 30 Dec '09

30 Dec '09

The code below fails to compile on g++ (GCC) 3.4.3: lambda_bind_test.cxx:9: error: `_1' undeclared (first use this function) lambda_bind_test.cxx:9: error: (Each undeclared identifier is reported only once for each function it appears in.) Commenting the include of boost::bind fixes it. How can the second header hide types defined in the first header? Shall I report a bug in trac or reopen this one?: https://svn.boost.org/trac/boost/ticket/3075 Is there any way in the long run the two libraries could be unified? All the asio examples use boost::bind? Should developers starting out a new code base use just one? Which one? #include <boost/lambda/bind.hpp> #include <boost/bind.hpp> //comment this line out and it compiles int foo(const char*); void test(){ using namespace boost::lambda; bind(foo,_1); }

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[serialization] Can't build first example from docs.
by Patrick Horgan 29 Dec '09

29 Dec '09

Help! And thanks:) Same error as on our code. I thought I'd go through all the documentation (BTW do you want notes on typos?) and come up to speed so I could figure out why our code (that someone else wrote), had this error. To my surprise, the first example I tried had the same no get_debug_info member error. What am I doing wrong? Using trunk Using gcc 4.4.1 or 4.5 Linux dell 2.6.31-17-generic #54-Ubuntu SMP Thu Dec 10 16:20:31 UTC 2009 i686 GNU/Linux make example1 g++ -ggdb -ansi -pedantic -Wextra -Wwrite-strings -Wformat=2 -Wall -fstrict-aliasing -O3 -Wstrict-aliasing=3 -std=c++0x example1.cpp -o example1 In file included from /usr/local/include/boost/archive/detail/abi_prefix.hpp:11, from /usr/local/include/boost/archive/shared_ptr_helper.hpp:35, from /usr/local/include/boost/archive/text_iarchive.hpp:100, from example1.cpp:5: /usr/local/include/boost/config/abi_prefix.hpp:12:3: error: #error double inclusion of header boost/config/abi_prefix.hpp is an error In file included from /usr/local/include/boost/archive/detail/abi_suffix.hpp:14, from /usr/local/include/boost/archive/text_iarchive.hpp:122, from example1.cpp:5: /usr/local/include/boost/config/abi_suffix.hpp:13:3: error: #error Header boost/config/abi_suffix.hpp must only be used after boost/config/abi_prefix.hpp In file included from /usr/local/include/boost/archive/detail/interface_oarchive.hpp:24, from /usr/local/include/boost/archive/detail/common_oarchive.hpp:20, from /usr/local/include/boost/archive/basic_text_oarchive.hpp:32, from /usr/local/include/boost/archive/text_oarchive.hpp:31, from example1.cpp:4: /usr/local/include/boost/archive/detail/oserializer.hpp: In static member function ‘static void boost::archive::detail::save_pointer_type<Archive>::polymorphic::save(Archive&, T&)’: /usr/local/include/boost/archive/detail/oserializer.hpp:441: error: ‘const class boost::archive::detail::basic_pointer_oserializer’ has no member named ‘get_debug_info’ In file included from /usr/local/include/boost/archive/detail/interface_iarchive.hpp:23, from /usr/local/include/boost/archive/detail/common_iarchive.hpp:23, from /usr/local/include/boost/archive/basic_text_iarchive.hpp:31, from /usr/local/include/boost/archive/text_iarchive.hpp:24, from example1.cpp:5: /usr/local/include/boost/archive/detail/iserializer.hpp: In member function ‘virtual void boost::archive::detail::iserializer<Archive, T>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const’: /usr/local/include/boost/archive/detail/iserializer.hpp:176: error: there are no arguments to ‘get_debug_info’ that depend on a template parameter, so a declaration of ‘get_debug_info’ must be available /usr/local/include/boost/archive/detail/iserializer.hpp:176: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated) /usr/local/include/boost/archive/detail/iserializer.hpp: In member function ‘void boost::archive::detail::iserializer<Archive, T>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const [with Archive = boost::archive::text_iarchive, T = gps_position]’: example1.cpp:62: instantiated from here /usr/local/include/boost/archive/detail/iserializer.hpp:173: error: ‘get_debug_info’ was not declared in this scope example1.cpp: At global scope: example1.cpp: In instantiation of ‘void gps_position::serialize(Archive&, unsigned int) [with Archive = boost::archive::text_iarchive]’: /usr/local/include/boost/serialization/access.hpp:118: instantiated from ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = gps_position]’ /usr/local/include/boost/serialization/serialization.hpp:74: instantiated from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = gps_position]’ /usr/local/include/boost/serialization/serialization.hpp:133: instantiated from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::text_iarchive, T = gps_position]’ /usr/local/include/boost/archive/detail/iserializer.hpp:182: instantiated from ‘void boost::archive::detail::iserializer<Archive, T>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const [with Archive = boost::archive::text_iarchive, T = gps_position]’ example1.cpp:62: instantiated from here example1.cpp:20: warning: unused parameter ‘version’ example1.cpp: In instantiation of ‘void gps_position::serialize(Archive&, unsigned int) [with Archive = boost::archive::text_oarchive]’: /usr/local/include/boost/serialization/access.hpp:118: instantiated from ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = gps_position]’ /usr/local/include/boost/serialization/serialization.hpp:74: instantiated from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = gps_position]’ /usr/local/include/boost/serialization/serialization.hpp:133: instantiated from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive, T = gps_position]’ /usr/local/include/boost/archive/detail/oserializer.hpp:148: instantiated from ‘void boost::archive::detail::oserializer<Archive, T>::save_object_data(boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::archive::text_oarchive, T = gps_position]’ example1.cpp:62: instantiated from here example1.cpp:20: warning: unused parameter ‘version’ make: *** [example1] Error 1 example.cpp is the first example in the serialization docs, reproduced here for completeness: #include <fstream> // include headers that implement a archive in simple text format #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> ///////////////////////////////////////////////////////////// // gps coordinate // // illustrates serialization for a simple type // class gps_position { private: friend class boost::serialization::access; // When the class Archive corresponds to an output archive, the // & operator is defined similar to <<. Likewise, when the class Archive // is a type of input archive the & operator is defined similar to >>. template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & degrees; ar & minutes; ar & seconds; } int degrees; int minutes; float seconds; public: gps_position(){}; gps_position(int d, int m, float s) : degrees(d), minutes(m), seconds(s) {} }; int main() { // create and open a character archive for output std::ofstream ofs("filename"); // create class instance const gps_position g(35, 59, 24.567f); // save data to archive { boost::archive::text_oarchive oa(ofs); // write class instance to archive oa << g; // archive and stream closed when destructors are called } // ... some time later restore the class instance to its orginal state gps_position newg; { // create and open an archive for input std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); // read class state from archive ia >> newg; // archive and stream closed when destructors are called } return 0; }

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Boost.Python and _GLIBCXX_DEBUG
by Christoph Groth 29 Dec '09

29 Dec '09

Using boost 1.40 and gcc 4.3.4 (same problem occurs with gcc 4.4.2) I have the following problem. After compiling the attached python module with the command g++ -shared -fPIC -o kernel.so python.cc box.cc -lboost_python -I/usr/include/python2.5 and executing python run.py I get the error message *** glibc detected *** python: free(): invalid next size (fast): 0x0000000001a32a30 *** This error does not occur when the macro _GLIBCXX_DEBUG is not being defined. It also does not occur when the contents of python.cc and box.cc are put into one file. In more complicated programs defining _GLIBCXX_DEBUG can lead to a "Segmentation fault". Not defining _GLIBCXX_DEBUG also helps there. Is there a way to deal with this short of not defining _GLIBCXX_DEBUG? Could it be a bug in Boost.Python? Thanks in advance, Christoph here are the files: file python.cc: **************************************************************** #include <boost/python.hpp> #define _GLIBCXX_DEBUG #include <vector> #include "box.hh" using namespace boost::python; BOOST_PYTHON_MODULE(kernel) { class_<Box>("Box", init<> ()) ; } **************************************************************** file box.cc **************************************************************** #define _GLIBCXX_DEBUG #include "box.hh" Box::Box() { } **************************************************************** file box.hh **************************************************************** #ifndef BOX_HH #define BOX_HH #include <vector> class Box { public: Box(); private: std::vector<int> blocks; }; #endif // BOX_HH **************************************************************** file run.py **************************************************************** #!/usr/bin/env python import kernel sys = kernel.Box() ****************************************************************

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[property tree] Property Tree equivalent for matching nodes with specific child data?
by Jesse Perla 29 Dec '09

29 Dec '09

The property tree library looks like a very good way for me to remove the tinyxpath and tinyxml dependencies in my project. However, I am confused by one usage pattern. I have a lot of properties like the following: <top> <struct1 name="bla"> <stuff> data specific to struct1 </stuff> <struct1/> <struct1 name="bla2"> <stuff> data specific to struct1 </stuff> <struct1/> <struct2 name="bla3"> <stuff2>data specific to struct2 </stuff2> <struct1/> </top> I need to be able to get the tree given the name. In xpath I would go something like: ""/top/struct1[@name='bla']/stuff" to get at that information. I realize I could embed a <name> underneath the struct1 in xpath as well, but how do I get back to the siblings? Any ideas on how best to use property tree for this kind of pattern? Thanks, Jesse

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[asio] posting a function to an io_service object
by Vilhelm Sundberg 29 Dec '09

29 Dec '09

Hi, I am trying to call a function by posting it to an io_service object running in a different thread from the main thread of the application. The problem is the function always gets called from the main thread. Basically I would like to do this with asio: #include <iostream> #include <boost/thread.hpp> using namespace std; void f() { cout << boost::this_thread::get_id() << endl; } int main(int argc, char *argv[]) { cout << "main thread: " << boost::this_thread::get_id() << endl; boost::thread t1(f); boost::thread t2(f); t1.join(); t2.join(); return 0; } The output is: main thread: 0x9739628 0x97392e8 0x9739488 Using Boost.Asio, f() always gets called from the main thread: #include <iostream> #include <boost/bind.hpp> #include <boost/thread.hpp> #include <boost/asio.hpp> using namespace std; using namespace boost::asio; void f() { cout << boost::this_thread::get_id() << endl; } int main(int argc, char *argv[]) { io_service ios1; io_service ios2; io_service::work w1(ios1); io_service::work w2(ios2); io_service::strand s1(ios1); io_service::strand s2(ios2); boost::thread t1(boost::bind(&io_service::run, &ios1)); boost::thread t2(boost::bind(&io_service::run, &ios2)); cout << "main thread: " << boost::this_thread::get_id() << endl; //s1.post(f); //s2.post(f); ios1.post(s1.wrap(f)); ios2.post(s2.wrap(f)); while (ios1.poll() > 0) ; while (ios2.poll() > 0) ; ios1.stop(); ios2.stop(); t1.join(); t2.join(); return 0; } The output is: main thread: 0x9739628 0x9739628 0x9739628 What is the correct way of posting/dispatching a function to an io_service running in a different thread, so that function is called from that thread? Thanks Vil

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Thread function deletion
by Alexander Gutenev 29 Dec '09

29 Dec '09

Why does boost::thread destroys its thread function only on boost::thread object destruction and not just after thread function returns?

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Compiling version 1.41 with /clr
by Dominique Aigroz 29 Dec '09

29 Dec '09

Dear all, I've upgraded from 1.39 to 1.41 and now I've got an error when compiling. error C2711: 'boost::detail::future_waiter::all_futures_lock::all_futures_lock' : this functon cannot be compiled as managed, consider using #pragma unmanaged 1> #pragma unmanaged is in effect 1> C:\Kadeo\Dev9\Thirdparty\boost_1_41_0\boost/thread/ future.hpp(411) : see source of the previous compiler diagnostic 1>C:\Kadeo\Dev9\Thirdparty\boost_1_41_0\boost/thread/future.hpp (416) : error C3821: 'boost::detail::future_waiter::all_futures_lock::all_futures_lock (std::vector<_Ty> &)': managed type or function cannot be used in an unmanaged function 1> with 1> [ 1> _Ty=boost::detail::future_waiter::registered_waiter 1> ] My dll is compiled with /clr flag, but i put #pragma unmanaged before include the boost header files. Does anyone have a solution for that problem. Regards, Dominique

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[asio] Echo server demo
by Michael Fowler 29 Dec '09

29 Dec '09

Hello. I tried using the code provided here: http://www.boost.org/doc/libs/1_41_0/doc/html/boost_asio/example/echo/block… to echo text back to a client but I haven't been successful. It seems to hang at > size_t length = sock->read_some(boost::asio::buffer(data), error); when the client sends a message. What is wrong? Thanks.

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Boost.Range fancify please
by anony 29 Dec '09

29 Dec '09

I have this variable definition: float vertices[][3] = { {-1, -1, 1}, {1, -1, 1}, {1, 1, 1}, {-1, 1, 1}, {-1, -1, -1}, {1, -1, -1}, {1, 1, -1}, {-1, 1, -1} }; I want to scale all elements of vertices, by some constant, for now I do it like this: BOOST_FOREACH(float& f, boost::make_iterator_range( boost::begin(vertices[0]), boost::end(vertices[7]))) { f *= scale; } But maybe something more beautiful could be done with Boost.Range?

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[Iterator] Interest in bzip2 compress/decompress iterators
by Jason Felice 28 Dec '09

28 Dec '09

I've written them for a work project. It would need to be essentially rewritten for Boost (different coding standards), but I'm willing to do it if there's interest and it would likely be accepted. It would depend on bzlib (part of bzip2) being installed. I noticed there's a gzip iostream, but no gzip iterator. This is a kind of precedent for the external dependency aspect. I've also written a class which produces a tar file in a streaming fashion to an output iterator. File contents are streamed in from input iterators. I'm not sure if this is useful or where it would go.

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