September 2009 - Boost-users

[units] meta_multiply units?
by Rupert Mazzucco 14 Sep '09

14 Sep '09

Hello, I cannot seem to figure out how to make a composite unit out of two existing units from the same system. For example, say I have a functor F which takes an argument of type F::arg_type = quantity<time> and returns a value of type F::ret_type = quantity<velocity> Now I want to write an integration function, which should return the correct type, something like template<class F> F::ret_type*F::arg_type // only conceptually integrate(F& f, typename F::arg_type a, typename F::arg_type b); so instantiating this with the above functor should produce a return type quantity<time*velocity==length>. How can I combine F::arg_type and F::ret_type to produce the correct return type for the function template? Thank you, Rupert -- Rupert Mazzucco <mazzucco(a)iiasa.ac.at> Research Scholar, Evolution and Ecology Program IIASA - Institute for Applied Systems Analysis Schlossplatz 1, 2361 Laxenburg, Austria Phone: +43 2236 807 522 Fax: +43 2236 713 13

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Data type to handle C++ and Boost streams?
by Adam Nielsen 13 Sep '09

13 Sep '09

Hi all, Bit of a basic question - I'd like to have some functions that work with files (using std::fstream) but can also handle boost::iostreams. Is there a data type I can use that can handle both? For example: void writeSomeData(std::fstream out); I can't pass a boost::iostream::stream to this function. What type can I use to achieve this? Many thanks, Adam.

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[boost.thread] boost thread on x64
by Pascal Kesseli 13 Sep '09

13 Sep '09

Hi friends Using the freshly created MinGW 64bit build, creating the boost 1.40 libraries with bjam worked flawlessly. However, when including boost/thread.hpp, I receive the following error: In file included from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/basic_timed_mutex.hpp:14, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/mutex.hpp:8, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/mutex.hpp:14, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/detail/thread.hpp:11, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/thread.hpp:22, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread.hpp:13, from ../src/main/com/emc/schedule/DailyRepetitiveTaskComposite.cpp:2: C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/interlocked_read.hpp: In function 'void boost::detail::interlocked_write_release(void* volatile*, void*)': C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/interlocked_read.hpp:71: error: cast from 'void*' to 'long int' loses precision In file included from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/mutex.hpp:8, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/mutex.hpp:14, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/detail/thread.hpp:11, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread/thread.hpp:22, from C:\Program Files\C++\boost\boost_1_40_0/boost/thread.hpp:13, from ../src/main/com/emc/schedule/DailyRepetitiveTaskComposite.cpp:2: C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/basic_timed_mutex.hpp: In member function 'void* boost::detail::basic_timed_mutex::get_event()': C:\Program Files\C++\boost\boost_1_40_0/boost/thread/win32/basic_timed_mutex.hpp:152: error: cast from 'void*' to 'long int' loses precision make: *** [src/main/com/emc/schedule/DailyRepetitiveTaskComposite.o] Error 1 However, on the stated line, I can't even make out a cast. Is boost_thread win64 compatible? g++ version: g++.exe (GCC) 4.4.1 20090505 (prerelease) Copyright (C) 2009 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Thanks for any help and best regards Pascal

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What is the way to access the data contained in a stream buffer?
by Ramon F Herrera 13 Sep '09

13 Sep '09

This is the relevant code: boost::asio::streambuf request; std::ostream request_stream(&request); request_stream << "GET " << argv[2] << " HTTP/1.0\r\n"; request_stream << "Host: " << argv[1] << "\r\n"; request_stream << "Accept: */*\r\n"; request_stream << "Connection: close\r\n\r\n"; // Send the request. boost::asio::write(socket, request); How can I convert the 'request.data' into a string or something? TIA, -Ramon

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Re: [Boost-users] What is the way to access the data contained in a stream buffer?
by Anders Dalvander 13 Sep '09

13 Sep '09

Ramon F Herrera wrote: > I have a follow-up question of a more general nature. I think the Boost > libraries are the greatest thing since sliced bread, but there are times > when a simpler approach will suffice. We can see in these 2 lines of > code that we are mixing STL with Boost: > > boost::asio::streambuf request; > std::ostream request_stream(&request); > > Is there any STL class that can be used above, instead of > boost::asio::streambuf? > Something like std::ostringstream? std::ostringstream request_stream; request_stream << "GET " << argv[2] << " HTTP/1.0\r\n"; request_stream << "Host: " << argv[1] << "\r\n"; request_stream << "Accept: */*\r\n"; request_stream << "Connection: close\r\n\r\n"; std::string request = request_stream.str(); Regards, Anders Dalvander

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Is there anything wrong with the Gmane newsgroup? + Interested in parsing tools and networking code
by Ramon F Herrera 13 Sep '09

13 Sep '09

Hello, I just joined the mailing list - Greetings to all. I have been trying for several day to post messages to the Boost Users newsgroup on Gmane. I didn't get any error message, but my postings never appeared. Boost is one of the best resources I have found in a very long time - Thanks for the effort! One of my main current interests is parsing. Trying to decide among the choices: - Regex - Spirit - Xpressive I could use some help with ASIO, too. -Ramon

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PBGL / Dynamic Property Maps complexity
by Mathieu Malaterre 12 Sep '09

12 Sep '09

Hi there, I am slowly discovering (Parallel) BGL. Could someone confirm the following: All the BGL examples I found handle dynamic properties (data attached to a vertex) using 'Dynamic Property Maps'. If I understand correctly dynamic_properties are basically a std::map. The complexity to get a value from a std::map is O(log(n)). Thus a graph traversal of all values is O(n * log(n)). If this is correct, my question is: is there another approach where I could have a O(1) complexity to access data associated with an edge ? Thanks, -- Mathieu

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[program_options]If a parameter in the command line contains white space, how to parse it ?
by yaoyansi 12 Sep '09

12 Sep '09

hi, all i use boost::program_options to parse cmd line parameters. Attachment has my code. And here is my test: tst.exe --wav c:/Program Files/Microsoft/a.wav --words "Hi, how are you?" --d "so,\ may\ be." the output is : wav:[c:/Program ] words:["Hi, ] d:["so,\ ] -------------------------------------------------- But, I want the result to be : wav:[c:/Program Files/Microsoft/a.wav ] words:[Hi, how are you?] d:[so, may be. ] What should I do now? Sorry for my poor English, And ,thanks in advance. ___________________________________________________________ 好玩贺卡等你发，邮箱贺卡全新上线！ http://card.mail.cn.yahoo.com/

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[interprocess] 1.40 compile error
by Moritz 12 Sep '09

12 Sep '09

Hi, I just started to port my application from boost 1.37 to 1.40 in order to get the remove() methods work in an appropriate way. Problem is now that the compiler is complaining about my use of named_condition.wait(lock). Here is what I get: ../boost_1_40_0/boost/interprocess/sync/named_condition.hpp|156|error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' ../boost_1_40_0/boost/interprocess/sync/named_condition.hpp|254|instantiated from 'void boost::interprocess::named_condition::wait(L&) [with L = boost::interprocess::scoped_lock<boost::interprocess::named_upgradable_mutex>]'| Thank you in advance for any hint.

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[streams] surplus output generated
by Sven Heithecker 12 Sep '09

12 Sep '09

Hi all, the code below using boost::iostream produces unwanted surplus output: Write: this ist a test output split into two parts Print: this flushes previous output Write: another test output t split into two parts The last line is a fragment of the first line which should not be there. I am using boost 1_39, gcc 4.3.2 [gcc-4_3-branch revision 141291] What am I doing wrong here ? BTW: the code is a stripped demo code. Originally, "true" devices are used instead of the dummy "0", and I use some home-brewn classes (instead of just "string") which require specialized output handling depending on the used device, therefore the direct call into the stream object. However, this makes no difference. Regards, Sven --------------------------------------------------------------------- #include <iostream> #include <boost/iostreams/stream.hpp> #include <boost/iostreams/concepts.hpp> using namespace std; namespace io = boost::iostreams; // "demo" strem sink class CTestSink: public io::sink { public: CTestSink(int dummy) {} // iostreams requires constructor argument public: streamsize write(const char *s, streamsize n) { cout << "Write: " << s; return(n); } void Print(const string &str) const { cout << "Print: " << str << endl; } }; // the real stream typedef io::stream<CTestSink> CTestOStream; // specialized output for "string" objects CTestOStream &operator<<(CTestOStream &stream, string &str) { // make sure previous output is flushed // (not required in this example) stream.flush(); stream -> Print(str); // specialized output handling return(stream); } int main() { // dummy "0" required by boost:iostreams CTestOStream testostream(0); testostream << "this ist a test output "; testostream << "split into two parts" << endl; string str("this flushes previous output"); testostream << str; testostream << "another test output " << endl; } -- Sven Heithecker GPG Fingerprint: 52F7 06C2 BF51 96CE DFF7 CC89 1A6B DFD5 BEC2 02A6

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