September 2010 - Boost-users - lists.preview.boost.org

Bjam problem - again
by Paul A. Bristow 26 Sep '10

26 Sep '10

I've moved to a new machine, and I can run bjam jobs from trunk, but when I try to run sandbox jobs, I am baffled by this message. Unable to load Boost.Build: could not find build system. --------------------------------------------------------- I:\boost-sandbox\boost-build.jam attempted to load the build system by invoking 'boost-build ;' but we were unable to find "bootstrap.jam" in the specified directory Unhelpfully, it doesn't seem to reveal what the 'specified directory' actually is. The files were copied over from a working system, so I can't see what has changed. The jamfile(s) are unchanged. I've got the following environment variables set: I:\boost-sandbox>set boost boost_build_path=i:\boost_1_44_0\tools\build\v2 boost_patches=i:\boost-patches boost_root=i:\boost_1_44_0 boost_sandbox=i:\boost-sandbox boost_trunk=i:\boost-trunk I:\boost-sandbox>bjam --debug_configuration just produces this message. I:\boost-sandbox>bjam -d5 --debug_configuration > debug.log produces the attached log, and the trunk log for comparison. Help! Thanks Paul PS Boost build is undoubtedly clever, but, sadly, not nearly clever enough for the abuse of very many users, judging by the Google entries for the above error message :-( --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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best tool in Boost for (massive) string replacement?
by alfC 26 Sep '10

26 Sep '10

With all the tools available in Boost and coming from a different backgroup is hard for me to choose what is the best tool in Boost to do a massive string replacement. The problem I have is the following, I have a map of replaced and replacing strings std::map<string,string> rep; rep["\\alpha"] = "a"; rep["\\beta"] = "b"; ... let's say about 100 of these. And I have an input/output file (few thousand lines) were I would like to do all this replacements. What is the best tool in boost to do this, Spirit, Regex, tokenizer, StringAlgorithm? My only approach so far is Regex and the implementation is very crude. I read the file line by line and do a loop over the replacement keys for each line. It is not even exploiting the fact that I have a map of replacements (compared to an array of replacements). It seems very slow. (Yes, it is like a 'sed' unix command replacement but with hundreds of replacement strings) Thank you, Alfredo

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[Proto] How to access the grammar of an expression?
by Roland Bock 24 Sep '10

24 Sep '10

Hi, ist there a way to access the grammar that was used to construct an expression? I have defined a metafunction template<class Left, class Right> struct grammar_less: mpl::false_ {}; which has specialization for some grammar combinations. Now I want to define a function that can take two arguments so that child0.grammar < child1.grammar Any idea how to do that? My test-code is attached. Regards, Roland

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[Filesystem] String corruption in path in V3 and Boost 1.44
by Will Watts 24 Sep '10

24 Sep '10

I have the following method: boost::filesystem::path Sfw::CFolders::GetModulePath() { char buffer[MAX_PATH+1]; chknzapi (GetModuleFileName (NULL, buffer, MAX_PATH)); return buffer; // Converted to fs::path object } Under Boost 1.43 this seemed to work fine. The char buffer is used to create a temporary path object, which is returned by value from the function. But when I upgraded to Boost 1.44, and recompiled with BOOST_FILESYSTEM_VERSION=3 and BOOST_FILESYSTEM_NO_DEPRECATED defined, I found that, although it still compiled, it no longer worked properly. Specifically, the contents of the path becomes corrupted to garbage. I got the impression that the path object returned, instead of containing a copy of the character string, retains a pointer to the original char buffer[] on the stack - which is naturally trampled on by subsequent activity. Changing the function to this: boost::filesystem::path Sfw::CFolders::GetModulePath() { char buffer[MAX_PATH+1]; chknzapi (GetModuleFileName (NULL, buffer, MAX_PATH)); return string(buffer); } seems to fix the problem. I admit I have not examined the code for the filesystem::path class - I am roundly intimidated by Boost code. Is my problem caused by a bug in the library introduced by 1.44, or am I just using the library incorrectly? Is my fixed version acceptable, or am I just 'lucky' that it seems to work? The environment is Visual C++ 10, targetting 32-bit. As well as the #defines listed above, I have also got BOOST_NO_RVALUE_REFERENCES defined, to address a compilation problem with another Boost library. Regards Will PS: Apologies if this is a dupe. I attempted to post this via an NNTP account, which I believed had the correct rights, but didn't seem to do the business. Applied Industrial Systems is a limited company registered in England. Registered number: 2552260. Registered office: 11 Riverview, The Embankment Business Park, Stockport, Cheshire SK4 3GN.

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[bind] Doubt regarding the use of shared_ptr with boost.bind
by Shiou Ming Lee 24 Sep '10

24 Sep '10

Hi, I have a doubt on using bind library. I pass the output of Bind to Asio library, and at certain point of time another thread will ask Windows I/O service to execute the function append(): m_ioService.post(m_strand.wrap( boost::bind(&LogWriter::append, (*logWritersItr), _logMessage, _logLevelString) )); The second param of Bind, (*logWritersItr), is a shared_ptr of LogWriter's subclass. The signature of LogWriter::append() is as following: virtual void append(const std::string& _logMessage, const std::string& _logLevelString) = 0; Base on document at http://www.boost.org/doc/libs/1_44_0/libs/bind/bind.html, the way I use bind will duplicate a copy of that shared_ptr. Any idea when will the duplicated shared_ptr become invalid so that the reference count decreases by one? Thanks, Shiou Ming

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Can I call async_write twice in a row?
by Germán Diago 23 Sep '10

23 Sep '10

Is this legal? I think I understood in the documentation that it isn't, but I'm not sure if it means this: void func() { async_write(....); async_write(...); } So, should I do this ALWAYS? void func() { async_write(..., another_func); } void another_func(const boost::system::error_code & ec, std::size_t bytes) { async_write(...); } Thanks in advance.

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Using boost with map<int, map<int, class> >
by przemyslaw.sliwa＠uk.bnpparibas.com 23 Sep '10

23 Sep '10

Hello, I have a data structure which basically is a map of a map. It looks follwing class clss { void postprocess() { .... } } typedef std::map<int, clss> ciMap; typedef std::map<int, ciMap> ciiMap; ciiMap test; now in order to call postprocess() on each element in the second map I have to do the follwing: for(ciiMap::iterator i_ptr=test.begin(); i_ptr!=test.end(); ++i_ptr) { ciMap& tmpMap = (*i_ptr).second; for(ciMap::iterator j_ptr=tmpMap.begin(); j_ptr!=tmpMap.end(); ++j_ptr) { cls& temp = (*j_ptr).second; temp.postprocess; } } Can boost help me reducing this ridiculous loop? Should I use lambda or boost::bind in order to do this? Couls someone help me with this? 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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[TypeTraits] is_arithmetic and is_enum together?
by Steve Lorimer 23 Sep '10

23 Sep '10

Is there a type trait that defines both is_arithmetic and is_enum together? (not is_scalar though) I find I'm doing this often: BOOST_STATIC_ASSERT(boost::is_arithmetic<Integer>::value == true || boost::is_enum<Integer>::value == true); which lead me to wondering if there was a more granular trait which included the two

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[ASIO] Access violation on io_service::work destructor
by Daniele Barzotti 23 Sep '10

23 Sep '10

Hi, In my code I have a io_Service and a work object shared among my classes: // Main io_service static boost::asio::io_service io_service; static boost::scoped_ptr<boost::thread> io_service_thread; static boost::asio::io_service::work* p_work; static BOOL thread_started; void io_worker_thread(void) { #if(WIN32 && _WIN32_DCOM) struct com_init { com_init() { CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); } ~com_init() { CoUninitialize(); } } initializer_object; #endif io_service.run(); io_service.reset(); thread_started = false; }; void Init(....) { if (!thread_started) { try { // create the work object on the heap p_work = new boost::asio::io_service::work(io_service); // run the IO service as a separate thread: // Instead of start the worker thread directly // by passing the io_service object, // I call the io_worker_thread function where // I can do some initialization tasks like // calling CoInitializeEx for COM io_service_thread.reset(new boost::thread(io_worker_thread)); thread_started = !thread_started; } catch (boost::thread_resource_error e) { // Failed to create the new thread return 0; } } } When my application ends and the io_service.run() returns I get: First-chance exception at 0x09299c18 (AxEuroATLib_debug.dll) in EuroSvr.exe: 0xC0000005: Access violation reading location 0xf0f0f0fc. at the following line (io_service.ipp): inline io_service::work::~work() { io_service_.impl_.work_finished(); } I wrong something? Regards, Daniele

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Re: [Boost-users] [asio]Why std::ofstream AND boost::asio::async_read() fails?
by Yasuhiko Yoshimura (informax.co.jp) 23 Sep '10

23 Sep '10

> I'm not able to see why downloading is sometimes fails in asio asyncread(). I found out my bug resolution that is moving the std::ofstream as a class member to stack of function calling itself. Thanks, Yasuhiko Yoshimura class ftp_client_dtp { // Start socket and etc. void start() { work_resolver_.reset(new boost::asio::ip::tcp::resolver(work_io_service_)); work_socket_.reset(new boost::asio::ip::tcp::socket(work_io_service_)); work_.reset(new boost::asio::io_service::work(work_io_service_)); work_thread_.reset(new boost::thread( boost::bind(&boost::asio::io_service::run, &work_io_service_))); ... // Start an asynchronous resolve to translate the server and service names // into a list of endpoints. ... } ... private: ... void handle_read_content(const boost::system::error_code& err) { if (!err || err == boost::asio::error::eof) { std::string spath = scurrentpath_ + "\\" + sfilename_; // insert the next line that the ofstream to stack. std::ofstream f(spath.c_str(), std::ios::binary | std::ios_base::out | std::ios_base::app | std::ios_base::ate); if (response_.size() > 0) { f << &response_; } f.close(); if (!err) { // Continue reading remaining data until EOF. boost::asio::async_read(*work_socket_, response_, boost::asio::transfer_at_least(1), boost::bind(&ftp_client_dtp::handle_read_content, shared_from_this(), boost::asio::placeholders::error)); } else { // eof std::cout << err; do_close(); } } else { std::cout << err; do_close(); } } void do_close() { work_socket_->close(); } // comment out the next line. // std::ofstream f; std::string sip_, sport_, scurrentpath_, sfilename_; boost::asio::streambuf request_; boost::asio::streambuf response_; boost::scoped_ptr<boost::asio::ip::tcp::resolver> work_resolver_; boost::scoped_ptr<boost::asio::ip::tcp::socket> work_socket_; boost::asio::io_service work_io_service_; boost::scoped_ptr<boost::asio::io_service::work> work_; boost::scoped_ptr<boost::thread> work_thread_; };

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