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

Threaded Daemon - boost::mutex::lock(): Assertion `!pthread_mutex_lock(&m)' failed.
by John D 28 Jun '09

28 Jun '09

Hi This seems an interesting error. I have an application that when executed as ./execute runs just as fine as can be. However when run with a a daemon that loads on boot, when activated it immediately crashes with. /usr/include/boost/thread/pthread/mutex.hpp:50: void boost::mutex::lock(): Assertion `!pthread_mutex_lock(&m)' failed. The cause of the problem clearly is the lack of an in your face shell which I know and is fine. I am wondering what advice anyone might have for having a stable boost threaded tty less executable that will run. I know it is something very small to change likely in the call to execute the application but please any help is appreciated, Thank you, John D

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[asio] STL issues OS X 10.5 (intel)
by Jeffrey Aigner 28 Jun '09

28 Jun '09

I am trying to learn the asio library via the tutorials on the website. I am using XCode on OS X 10.5 (intel). After compiling successfully, I get runtime errors (after program listing): Program: #include <iostream> #include <boost/asio.hpp> #include <boost/date_time/posix_time/posix_time.hpp> int main() { boost::asio::io_service io; boost::asio::deadline_timer t(io, boost::posix_time::seconds(5)); t.wait(); std::cout << "Hello, world!\n"; return 0; } Runtime Errors: Macintosh:Debug jaigner$ ./proxy /Developer/SDKs/MacOSX10.5.sdk/usr/include/c++/4.0.0/debug/ safe_iterator.h:127: error: attempt to copy-construct an iterator from a singular iterator. Objects involved in the operation: iterator "this" @ 0x0x1002b0 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIPvPN5boost4asio6detail11timer_queueINS6_11time_traitsINS5_10posix_time5ptimeEEEE10timer_baseEEEEN15__gnu_debug_def4listISG_SaISG_EEEEE (mutable iterator); state = singular; } iterator "other" @ 0x0xbffff4e4 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIPvPN5boost4asio6detail11timer_queueINS6_11time_traitsINS5_10posix_time5ptimeEEEE10timer_baseEEEEN15__gnu_debug_def4listISG_SaISG_EEEEE (mutable iterator); state = singular; } Abort trap Any help would be appreciated! --Jeff Aigner

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A question on for_each() and placeholder.Can any one with kindness help me?
by fmingu 28 Jun '09

28 Jun '09

By using Dev-C++, I used lambda expression, I want to know that if I white: typedef std::vector<int> vect1; std::vector<vect1> vect2; vect2 vect2Instance; then std::for_each(vect2Instance.begin(),vect2Instance.end(), std::for_each(_1.begin(),_1.end(),_1+=2)); is legal or not? And if legal ,Does the first two _1's mean a number in vect2 (i.e. a vect1) and the last _1 is a number in vect1(i.e. a int)? Can any one with kindness help me?

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variant within a recursive_variant?
by Matthew L. Creech 27 Jun '09

27 Jun '09

Hi, I'm wondering if anyone has successfully embedded a boost::variant<> within a recursive variant. The program below illustrates what I'm trying to do: ============= #include <vector> #include <string> #include <boost/variant.hpp> typedef boost::variant< double, std::string > a_t; struct b_t { }; typedef boost::make_recursive_variant< a_t, b_t, std::vector<boost::recursive_variant_> >::type c_t; int main() { a_t a(20.0); c_t c(a); return 0; } ============= With GCC, this gives me: ... boost/variant/variant.hpp:1269: error: no matching function for call to 'boost::detail::variant::initializer_root::initialize(void*, double&)' Normal variant-within-a-variant works fine (i.e. if I remove the vector, and just declare c_t without make_recursive_variant<>). And make_recursive_variant<> with plain types works as well (i.e. if a_t is a non-variant type). But I can't figure out how to make the two work together... Any help would be greatly appreciated. Thanks! -- Matthew L. Creech

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How to Compile Boost for All Versions of Visual Studio
by Altaf Navalur 27 Jun '09

27 Jun '09

Hello, I have installed VS 2003, VS 2005 & VS 2008 in my PC. I have to work on all these versions. When I compile boost, it only compiles for VS 2008. How do I compile it for all the three IDE`s? Thanks, Altaf -- An eye for an eye only ends up making the whole world blind.

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fusion::result_of::invoke_function_object and references
by Mike Tegtmeyer 27 Jun '09

27 Jun '09

I have another question regarding compilation failures with fusion. If this has been discussed before, can someone please point me to the right location. If not... Is there some reason the application of result_of::invoke_function_object fails to compile for sequence argument references? ie: result_of::invoke_function_object<doit, fusion::vector<int>&>::type Digging a little, it seems that the failure is due to the size<> operator doesn't work with reference types (or is expecting the reference to be stripped prior to this point). I understand that to avoid unnecessary copies, tiers are typically used but in the case where chains of invoke_function_object would like to be strung together where there is an assignment or construction from the actual return value to a variable declared as the type obtained from result_of (in a fold for example), it seems that the vector copy is unavoidable (at least in my reading) unless the argument vector is a const reference. Is this an oversight or am I missing something? Basically I am trying to string together N function objects in the sequence where the ith object gets called with the result of the i-1th object (where each has a different argument list) using fold and I am running into extraneous copies of the return value. I can post a full example if needed. Thanks in advance, Mike error message: /opt/local/include/boost/fusion/sequence/intrinsic/size.hpp:28: error: const boost::fusion::vector<int, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_>& is not a class, struct, or union type See code below. #include <boost/fusion/container/vector.hpp> #include <boost/fusion/functional/invocation/invoke_function_object.hpp> namespace b = boost; namespace bf = boost::fusion; struct doit { template <typename Sig> struct result; template <typename Self, typename T> struct result< Self(const T &) > { typedef int type; }; template <typename T> int operator()(const T &t) const { return 1; } }; #if !OK typedef bf::result_of:: invoke_function_object<doit,const bf::vector<int>&>::type result_type2; #else typedef bf::result_of:: invoke_function_object<doit,const bf::vector<int> >::type result_type2; #endif int main() {return 0;}

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Compile errors inside boost::asio code I can't affect.
by Michael.Broida＠thomsonreuters.com 27 Jun '09

27 Jun '09

Hi! We've been using Boost 1.38.0: WinXP SP3 on 32-bit box VisualStudio 2005, MSVC++ 8.0, 32-bit builds. I've just rebuilt Boost 1.38.0 on another system for 64-bit builds: Windows Server 2008 Enterprise SP1 VisualStudio 2008, MSVC++ 9.0, 64-bit builds. Found no visible build errors during the Boost build. Yet when I build our own code on the 64-bit system, I get these three compile errors deep inside boost::asio code that I have no control over: >>---------------- error C2664: 'QueueUserAPC' : cannot convert parameter 1 from 'void (__cdecl *)(ULONG)' to 'PAPCFUNC' D:\dev\3rdParty_x64\include\boost\asio\detail\win_thread.hpp 151 >>---------------- error C2664: 'GetQueuedCompletionStatus' : cannot convert parameter 3 from 'DWORD *' to 'PULONG_PTR' D:\dev\3rdParty_x64\include\boost\asio\detail\win_iocp_io_service.hpp 142 >>---------------- error C2664: 'GetQueuedCompletionStatus' : cannot convert parameter 3 from 'DWORD *' to 'PULONG_PTR' D:\dev\3rdParty_x64\include\boost\asio\detail\win_iocp_io_service.hpp 430 >>---------------- The "D:\dev\3rdParty_x64" is where I've installed the includes & libs for Boost and other components. As you can see, those errors are not in our code; they're deep in the ASIO code itself, and I don't see how we could be causing them. I didn't write our code that uses ASIO, so I don't know anything about what ASIO is trying to do there. :( Since I couldn't find any other complaints online about this, I'm flailing around for support. Any pointers would be appreciated. Pertinent data: 64-bit WindowsServer2008 SP1 on Intel 64-bit box VisualStudio2008 SP1 (SP2 is still RC, I think, so we can't use it.) Our projects using "x64" configuration, so uses x64 compiler. Boost built with x64 compiler via: toolset=msvc-9.0 address-model=64 Thanks! Mike This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters.

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[format] Thread safety of boost::format
by James Madison 26 Jun '09

26 Jun '09

I was browsing the boost::format docs and did not find anything about the Thread safety of boost::format. Essentially I want to craft a bunch of error handling methods like this: void ProcessError(...args...) { static boost::format formatter(...); //Try to save the cost of creating this for every single error //do stuff LOG(boost::str(formatter % ...args...); } This method would be called from many, many threads. Is this considered safe? Is there some general information about the thread safety of boost::format methods somewhere in the docs?

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[MultiArray] Postcondition of assignment
by dariomt＠gmail.com 26 Jun '09

26 Jun '09

Hi list, I see in the MultiArray concept documentation that the operator= has the postcondition (*.this) == x; But if I use overlapping memory this postcondition does not hold. The attached program asserts trying to verify the postcondition. In this program I have a 2D square matrix represented as a multi_array. I then assign column j to row i. Depending on the relationship of i and j and how the implementation of operator= does the traversal over the elements to be copied, the program may not satisfy the mentioned postcondition. May I suggest some note in the documentation about this. Is it possible that the traversal can be done forward or backward to guarantee the said postcondition even in the face of overlapping memory? Thanks. PS: Maybe I'm just using multi_array incorrectly. It that's the case, please do help me to use it correctly. #include <boost/multi_array.hpp> #include <iostream> #include <iterator> typedef boost::multi_array<double, 2> array_type; array_type::array_view<1>::type row(array_type & m, size_t i) { typedef array_type::index_range range; array_type::index_gen indices; return m[ indices[i][range(0,m.shape()[1])] ]; } array_type::array_view<1>::type col(array_type & m, size_t i) { typedef array_type::index_range range; array_type::index_gen indices; return m[ indices[range(0,m.shape()[0])][i] ]; } void print(array_type & m) { typedef array_type::index_range range; array_type::index_gen indices; for (size_t i = 0; i < m.size(); ++i) { array_type::array_view<1>::type r = row(m, i); std::copy( r.begin(), r.end(), std::ostream_iterator<double>(std::cout, " ")); std::cout << std::endl; } std::cout << std::endl; } int main() { typedef array_type::index index; array_type A(boost::extents[3][3]); int values = 1; for(index i = 0; i < 3; ++i) for(index j = 0; j < 3; ++j) A[i][j] = values++; print(A); array_type::array_view<1>::type r = row(A, 2); array_type::array_view<1>::type c = col(A, 1); c = r; print(A); // this assert fires because the contents of the row // and the column are not equal after the assigment // the postcondition does not hold assert( c == r ); return 0; }

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[Flyweight] Enumerating all values in the factory?
by mailinglists 26 Jun '09

26 Jun '09

Hi, thanks for the flyweight library, looks good. Is there a way to enumerate all values in a factory? Consider my use case: I have a large set of data. Each element has a user defined 'tag', implemented as a flyweight<std::string>. Now the user wants to find all elements where the 'tag' matches a regex. Calculating the regex match for all elements in the dataset is expensive. If I could find all matching tags in the flyweight factory first, searching the elements is reduced to comparing two flyweights rather than doing a regex match. Consider: struct data { flyweight<std::string> m_tag; }; vector<data> m_some_data; The straight forward approach is costly: for (iterator i=m_some_data.begin(); i!=m_some_data.end() && regex_match(*i); ++i) ; with the regex match calculated for every element in the vector. A much more efficient solution is to find all elements in the flyweight factory that match the regex and then compare the flyweights. vector<flyweight<std::string> > m_matching_tags=find_matching_flyweights(regex); Now iterating over the data needs to compare two flyweights per data element which should be a lot faster than doing a regex match. Is there a way? Regards Hajo

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