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

[thread] documentation complaints
by Robert Ramey 21 Oct '10

21 Oct '10

I had occasion to look into the thread documentation after many years. It was in the course of explaining the benefits of using boost libraries to a programmer who was unfamiliar with them. Somehow I remember the old documentation as being much more helpful. I think I remember tutorials and a faq explaining things why semaphores weren't inlcuded etc. I remember finding this to be very helpful. My original interest in boost was sparked by reading this documentation. The current system seems more complete and the documention more formal and correct. But it needs tutorials which explain how to use the library to solve problems and to explain the examples. It also needs a section to explain the design decisions. Robert Ramey

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foreach question
by Neal Becker 21 Oct '10

21 Oct '10

The following loop iterates over strings in result (which comes from boost::split). Is there a way to include the integer enumerator 'col' into the FOREACH loop? In python that would be spelled for col,s in enumerate (result): ... int col = 0; BOOST_FOREACH (std::string s, result) { H(row, col) = boost::lexical_cast<int> (s); ++col; }

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[Variant] Tree like structure with variant
by dariomt＠gmail.com 21 Oct '10

21 Oct '10

Hi all, I need a tree-like structure like the following boost::variant< int, std::vector<tree>, std::map<std::string, tree> > tree; So, my tree can have an int, or a list of trees, or a map of trees. Of course this is not possible, and I've been trying to use boost::recursive_wrapper. I have looked at the example in the documentation, but and I'm not able to achieve what I want. My feeling is that I'm missing an extra 'node' level somewhere, but since all the types I'm using are typedefs, I cannot forward delcare it to break the cyclic reference... I would appreciate help with this. Thanks in advance.

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Passing a boost::unordered_set as the result map to boost::split
by Jeremy Stribling 21 Oct '10

21 Oct '10

Anyone here know the answer to this question? http://stackoverflow.com/questions/3981123/passing-a-boostunordered-set-as-… Thanks, Jeremy

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[PropertyTree] Adding comments to existing property tree object
by René Perlberg 21 Oct '10

21 Oct '10

Hello to everyone, I wonder whether it is possible to add comments to an existing property tree object. To be more specific: I read in some XML files and change some attribute values (both relaized using property tree). In addition to that I would like to add some comments to a specific path in the property tree. Looking inside the code of property tree I found a function 'write_xml_comment', but I'm not sure whether and how this function may be used to address my problem. With kind regards, René.

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[ASIO] Problem with reading of serial ports using ASIO
by Jim Donaldson 20 Oct '10

20 Oct '10

Hi All, I'm having some problems using Boost ASIO on Windows XPSP3, 32 bit. I'm trying to set-up an asynchronous read from a serial port on the computer (actually a USB port masquerading as a serial port). The code is at http://gist.github.com/634618 We regularly call the function PCTimeoutUart::wait( iseSize_t len, uint32 timeoutInMS ) which wraps the calls to the boost asio libraries. This creates a deadline_timer, and binds it to our timeout callback (PCTimeoutUart::finishedTimer) It also calls async_read_some on the boost::asio::serial_port object m_port to read the required length, and binds that to the PCTimeoutUart::finishedRead callback. We call the runone() function on m_io, which is declared in the header as a boost::asio::io_service and has been passed to both the timer and serial port's constructors. We continually call this in a loop until either m_timedOut has been set by the asynchronous call back to PCTimeoutUart::finishedTimer or m_finishedRead has been set via the call back to PCTimeoutUart::finishedRead Normally, this works well. However, there are certain scenarios when it fails to write anything to the buffer, despite the fact that finishedRead() is called with error = 0 and the correct length . I've checked by initializing the buffers with a couple of different values and each time, it's clear that the buffer is being passed back without those values being altered. Strangely, it is always when the string sent by the external device is '\r\nNACK:XX\r\n' where XX is a 2 character ascii number. I've got portmon running on the serial port and it confirms that the data has been correctly received from the external device. We've debugged it as far as putting a break-point on line 71 and at that point can see that the system thinks that a read is complete, n bytes have been returned, but only some of those bytes are in buffer. If anyone could offer any views on why we may be having problems, or places that we could look, then that would be very much appreciated. Thanks in advance, Jim

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Methods prefixed by cdecl?
by Ven Tadipatri 20 Oct '10

20 Oct '10

Hi, I'm using Windows 7 (64 bit) and I'm trying to compile and link my code against the regex libraries. It compiles fine, but at link time, it can't find any of the methods in the regex library. But the methods it's looking for are prefixed by "__cdecl". I've tried compiling my code with the /Gd and /Gz options, and neither seemed to work. Here's what the error looks like: [ERROR] ResourceURI.obj : error LNK2019: unresolved external symbol "private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __cdecl boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)" (?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AEAAAEAV12@PEBD0I@Z) referenced in function "public: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __cdecl boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::assign(char const *,char const *,unsigned int)" (?assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@QEAAAEAV12@PEBD0I@Z) [ERROR] ResourceService.obj : error LNK2001: unresolved external symbol "private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __cdecl boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)" (?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AEAAAEAV12@PEBD0I@Z) [ERROR] AtomicParsingExpression.obj : error LNK2001: unresolved external symbol "private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __cdecl boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)" (?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AEAAAEAV12@PEBD0I@Z) [ERROR] AbstractLoopingVariable.obj : error LNK2001: unresolved external symbol "private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __cdecl boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)" (?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AEAAAEAV12@PEBD0I@Z) When I do a dumpbin /symbols on the regex library I built, it does contain the methods above (as far as I can tell) 26F 00000000 SECT92 notype () External | ?assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@QAEAAV1 2@PBD0I@Z (public: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __thiscall boost: :basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::assign(char const *,char const *,unsigned int)) CB4 00000000 SECT40D notype () External | ?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AAEAAV12@PBD0I@Z (private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __thiscall boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)) Any ideas on how to get my programs to link against the methods in the regex library? Thanks, Ven

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Boost Fiber Compile error -- Boost task
by Glenn Macgregor 20 Oct '10

20 Oct '10

Hi All, I am in the process of trying to get boost task compiled and working with Boost 1.43.0. As far as I can tell it relies on boost fiber and boost context as well so I got them from the boost vault. I am using: * boost.context-0.2.0 * boost.fiber-0.5.1 * boost.task-0.4.2 I have copied these into my boost 1.43.0 build area and have run bjam as normal: Component configuration: - context : not building - date_time : not building - fiber : building - filesystem : not building - graph : not building - graph_parallel : not building - iostreams : not building - math : not building - mpi : not building - program_options : not building - python : not building - random : not building - regex : not building - serialization : not building - signals : not building - system : not building - task : not building - test : not building - thread : not building - wave : not building Below is the first couple errors I get but all of the following errors are of the same type: .\boost/fiber/strategy.hpp(123) : error C2492: 'boost::fibers::strategy::active_ fiber' : 'thread' data may not have dll interface .\boost/fiber/strategy.hpp(123) : error C2492: 'protected: static boost::fibers: :fiber * boost::fibers::strategy::active_fiber' : 'thread' data may not have dll Interface This seems to have to do with the __declspec(thread) but I am not very familiar with that so I can't really do much debugging. My build environment is: Windows XP64 VisualStudio 2008 Thanks in advance for any help. Glenn

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DLL Load Failed
by Monde, John 20 Oct '10

20 Oct '10

Hi, I am having a problem moving my boost python extension to a different machine than my development machine. On my development machine everything works great, I can access my C++ classes through python without any problems but when I copy my .pyd (Python_ext.pyd) to my target machine I get the error "DLL Load failed The specified module could not be found" in my Python program when I attempt to import the .pyd (import Python_ext) I am using Boost_1_42. The .pyd was built using BJAM and my compiler is MSVS 2003 and python26. Python26 is on both the development and the target machine. I had similar problem when I moved my python .pyd extension module to a different directory on my development machine but I fixed that by copying the boost dll boost_python-vc71-mt-gd-1_42.dll to the directory with my .pyd module and it ran great there. I tried to do the same thing on my target machine. I copied my python program, the .pyd extension module and the boost DLL (boost_python-vc71-mt-gd-1_42.dll) to the same directory on my target machine and still get the same error. Both machines are windows XP. To test this I am using a simple test C++ class that just receives two numbers and prints out there sum so I do not believe I am bringing in any other dlls. I am sure this is a simple problem and I am just missing it. Any help would be greatly appreciated. Thanks John

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[spirit::qi] assertion during parsing
by Ovanes Markarian 20 Oct '10

20 Oct '10

Hello *, I have a strange problem. When parsing some output boost::spirit::qi parser aborts the application stating the following error message: /local/include/boost/spirit/home/support/char_encoding/ascii.hpp:256: static int boost::spirit::char_encoding::ascii::isspace(int): Assertion `isascii_(ch)' failed. Indeed my input sequence is: ~B"þ¯Þº~N But is it really a reason to assert the parser and crash the app? This input would not match my grammar, so from my point of view (as library user) it is just fine: not to match the input, without any assertions. And I should be able to decide what to do next. I use boost 1.44 with gcc (GCC) 3.4.6 20060404 (Red Hat 3.4.6-11) Many thanks for support, Ovanes

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