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asio ip::tcp::socket::read(), always returns end of file
by Lloyd 06 Jun '11

06 Jun '11

Hi, I have an asio::ip::tcp::socket. Whenever I try to read from it, it throws an exception "end of file". But it is possible to write to the socket at any time! This is a client side application, it connects to the server using asio::async_connect(). The server is sending back the data, I checked it with wireshark. I tried using the both async_read() and read(), in both cases it fails with the same error. But both async_write(), and write() works perfectly. What could be the reason? This is how the read call implemented ... .... boost::asio::streambuf b; boost::asio::read(sock,b); //This line causes exception ... Thanks, Lloyd

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Re-Introduction
by John M. Dlugosz 06 Jun '11

06 Jun '11

I'm not a stranger to this list, but I am subscribing from a new address. I was subscribed at my previous employer, and participating on these lists last year. I want to say "hi" again, get my email set up, and get past the moderated new-subscriber stage. I'll be musing on Ranges and other topics shortly. —John (John Długosz)

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boost::asio asynchronous read problem
by Sebastian Götte 05 Jun '11

05 Jun '11

Hello, I have a problem when asynchronously reading from a serial port via boost::asio. The application should exchange a few commands and status bytes with the device, then the device starts sending data and the application listens and parses this data. A diagram of the initialization procedure is attached to this mail. I implemented this process using the Qt framework, and it works (data is being displayed as expected). Now I re-implemented the same procedure as a gnuradio module using boost::asio (i.e. a shared library with a nice python wrapper) -- and the initialization seems to work, but I did not succeed in reading anything after that. The constructor of the gnuradio module is being called on startup and does the initialization. After that, the "work" method is called in an infinite loop and should read and parse the data, and since this module is a source module I think it is ok that this call is blocking. The data that should come from the serial port after Initialization looks like this (shown is one "burst", this is sent 125 times a second): [\FX\FX\FX\FX\ X\FX\FX\FX\FX\ X\FX\FX\FX\FX\ X\FX\FX\FX\FX] Where F is a hexadecimal digit, [, ] and \ are the respective ascii characters, and X is any value of no interest (but should be 0x00). From this "line" (not delimited by \n, but by [ and ]) the four hex digit groups shall be extracted: FFFF FFFF FFFF FFFF ...and then be converted to four signed words (It does not need to be fast, and this format was pretty debugging-friendly). My problem is that after the device has been initialized successfully (all init methods have been executed) the read handler registered when async_read is called in work is never executed (I verified async_read is being called). The output of a test run (loading the module, thereby initializing it, then calling work(...) repeatedly) looks like this: -01--rt--02-bar-wh--03--04--01--wh--05--06--wh--07-foo-08--wh-gr_block_executor: source <gr_block openmind_buspirate_source_s (2)> produced no output. We're marking it DONE. I would expect this output followed by an output similar to the first line described above ([\FX\FX...). I use an aptosid linux, kernel 2.6.39-0 i686 and my gcc's answer to --version is gcc (Debian 4.6.0-10) 4.6.1 20110526 (prerelease) My libtool's version is 2.4 and my gnuradio version 3.3.0. I use boost 1.46. My autoconf version is 2.68, my automake version 1.11.1, my make version 3.81. Since this is a lot of code I do not include it here. The code of the important part of the working Qt-based app may be found here: https://github.com/jaseg/openmind-viewer/blob/09db5ba834d8d2c49cb239b1933f2… https://github.com/jaseg/openmind-viewer/blob/09db5ba834d8d2c49cb239b1933f2… Whereas the boost::asio-based code is available here: https://github.com/jaseg/openmind-viewer/blob/02fac3937fe625c85f0d05813ad9d… https://github.com/jaseg/openmind-viewer/blob/02fac3937fe625c85f0d05813ad9d… I would be glad about any suggestions. Sebastian

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[Interprocess 1.46.1] IsolationAwareLoadLibraryA not found by linker
by Remi 04 Jun '11

04 Jun '11

I added some shared memory headers from boost::interprocess to my project and I got the linker error: error LNK2028: unresolved token (0A001325) "extern "C" void * __stdcall IsolationAwareLoadLibraryA(char const *)" (?IsolationAwareLoadLibraryA@ @$$J14YGPAXPBD@Z) referenced in function "void * __cdecl boost::interprocess::winapi::load_library(char const *)" (?load_library@winapi@interprocess@boost@@$$FYAPAXPBD@Z) I'm using Visual C++ 2008 Express compiler (from 2010 IDE) and Windows SDK 6.0A. kernel32.lib is added in linker settings. What's the fix?

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[Boost][spirit] Confused about spaces!
by Germán Diago 03 Jun '11

03 Jun '11

Hello. I'm trying to implement a very basic parser but I'm stuck at the beginning of it. The parser will be fed with input from a very basic minilanguage to execute tests. I want that the first line begins literally like this: begin TestActions But with my current implementation I can't: template <class FwdIterator> struct TestFileParser : qi::grammar<FwdIterator, Test (), qi::ascii::space_type> { TestFileParser() : TestFileParser::base_type(start_) { using namespace boost::spirit::qi; start_ = lit("begin") >> lit("TestActions"); } qi::rule<FwdIterator, Test (), qi::ascii::space_type> start_; }; Because this implementation matches "beginTestActions" as well. And I want them to be different words. If I put a space between them, my rule complains because its attribute must be a Test(). And if I put in the middel a ' ' it doesn't work anymore. What's wrong with spaces? I'm using phrase_parse with qi::ascii::space skipper. Thanks in advance.

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[test] CLOSE and CLOSE_FRACTION tolerance
by Edward Diener 03 Jun '11

03 Jun '11

I am trying to understand the tolerance value passed as the last parameter to the BOOST_XXX_CLOSE and BOOST_XXX_CLOSE_FRACTION macros. The doc says that for the former the value is percentage units while for the latter it is the fraction of absolute values being compared. But in each case there are two values, not just one. Which of the two values are used to determine the tolerance amount in each case ? If both values are being used in each case, how is the tolerance amount computed from the tolerance value passed ?

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Using function operator in lambda expression
by Alexander Khomyak 03 Jun '11

03 Jun '11

Hi. According lambda documentation <http://www.boost.org/doc/libs/1_38_0/doc/html/lambda/le_in_details.html #lambda.operator_expressions> there is a possibility to use function call operator in lambda expression. But I can't compile following code using MS Visual Studio 2003.NET compiler: #include <boost/lambda/lambda.hpp> using namespace boost::lambda; int foo(int i) { return i; } Somewhere in main function: (_1(1))(foo); Could you give me example of using function call operator in lambda expression? In advance thank you very much.

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boost::assign::list_of and C++0x
by Travis Gockel 03 Jun '11

03 Jun '11

I'm moving a fairly large project over to C++0x, since it is about to be published (crosses fingers) and we need to stay up with the times. In this project, we use the wonderful boost::assign::list_of to assign collections (since initializer lists don't exist yet). We are using g++ 4.5.1 and Boost 1.46.1. When switching to C++0x, bits of code like this break: std::vector<int> vec; vec = boost::assign::list_of(1)(2)(3); with the following error: break_list_of.cpp:7:41: error: ambiguous overload for ‘operator=’ in ‘vec = ((boost::assign_detail::generic_list<int>*)boost::assign::list_of(const T&) [with T = int]().boost::assign_detail::generic_list<T>::operator() [with T = int, boost::assign_detail::generic_list<T> = boost::assign_detail::generic_list<int>, boost::assign_detail::generic_list<T>::Ty = int](((const boost::assign_detail::generic_list<int>::Ty&)((const boost::assign_detail::generic_list<int>::Ty*)(&2)))))->boost::assign_detail::generic_list<T>::operator() [with T = int, boost::assign_detail::generic_list<T> = boost::assign_detail::generic_list<int>, boost::assign_detail::generic_list<T>::Ty = int](((const boost::assign_detail::generic_list<int>::Ty&)((const boost::assign_detail::generic_list<int>::Ty*)(&3))))’ /usr/include/c++/4.5/bits/vector.tcc:156:5: note: candidates are: std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = int, _Alloc = std::allocator<int>] /usr/include/c++/4.5/bits/stl_vector.h:336:7: note: std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::vector<_Tp, _Alloc>&&) [with _Tp = int, _Alloc = std::allocator<int>, std::vector<_Tp, _Alloc> = std::vector<int>] /usr/include/c++/4.5/bits/stl_vector.h:357:7: note: std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(std::initializer_list<_CharT>) [with _Tp = int, _Alloc = std::allocator<int>, std::vector<_Tp, _Alloc> = std::vector<int>] The problem is that there are now multiple ways to assign to vectors (and all the other collection types). Ideally, I would replace all usage of boost::assign::list_of with C++0x initializer lists, but, alas, I am lazy. Furthermore, I think I know how to fix this (see example below) and think the Boost community would benefit from having boost::assign::list_of work in C++0x and C++. template <typename T> struct is_initializer_list : boost::false_type { }; template <typename T> struct is_initializer_list<std::initializer_list<T> > : boost::true_type { }; template <typename T> struct wrapped_type { wrapped_type(const T& val) : _val(val) { } template <typename TOut, // use new support for default template arguments in functions typename TPhony = typename boost::disable_if<is_initializer_list<TOut> >::type > operator TOut() const { return _val; } private: T _val; }; I was wondering if anybody has solved this problem (or a similar one) already. I would patch it myself, but I only have g++ and clang to test it on. Also, there is a high probability that my solution is flawed in some way. Thanks for the help! And, as always, thanks for the wonderful library. -- - Travis Gockel

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Re: [Boost-users] [range] cannot use lambda predicate in adaptor with certain algorithms
by Michel MORIN 03 Jun '11

03 Jun '11

Hi Daniel, Daniel Walker wrote: > At some point, BOOST_RESULT_OF_USE_DECLTYPE may be defined by default, > probably when there's enough user interest, so thanks for cc'ing me. > The reason it is currently not defined by default is that it is > possible that it could introduce breaking changes to some C++03 > function objects; e.g. if a function object defines result_type to be > some type other than the type of a call expression, then in C++03 > result_of would give the user-specified result_type rather than the > actual result type, whereas in C++0x result_of always gives the actual > result type. For example: > > #include <boost/type_traits.hpp> > #include <boost/utility/result_of.hpp> > > struct f { > typedef int result_type; > double operator()(double); > }; > > int main() > { > using namespace boost; > typedef result_of<f(double)>::type type; > #ifdef BOOST_RESULT_OF_USE_DECLTYPE > static_assert(is_same<type, double>::value, ""); > #else > static_assert(is_same<type, int>::value, ""); > #endif > } Thank you for explaining the problem. And yes, backward compatibility is always problematic. IMO, this use case is not the intended use of boost::result_of, so is it reasonable to deprecate this? And how about adding a "Note" that warns this kind of codes will break in the future to the documentation? Regards, Michel P.S. Eric just completed a patch for BOOST_NO_DECLTYPE_N3276: http://permalink.gmane.org/gmane.comp.lib.boost.devel/219979

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[asio] custom baud rates?
by Frank 02 Jun '11

02 Jun '11

Hello, I need to use a 500000 baud rate with the serial port. When I attempt to set this baud rate I get an EINVALID. How can I use custom baud rates with asio? I'm running on Mac OS X 10.6. Note that I can use the 500000 baud rate just fine on windows running .Net (i.e. not asio). Thanks, Frank

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