September 2008 - Boost-users - lists.preview.boost.org

library accumulator, example sum_accumulator
by Kim Kuen Tang 03 Sep '08

03 Sep '08

Hi all, i ' ve written a piece of code to get the class sum_accumulator working which is described in the user's guide http://boost-sandbox.sourceforge.net/libs/accumulators/doc/html/accumulator…. The function result must be provided with a struct dont_care. And the constructor of dont_care must be provided with a value to get an instanciation. In my opinion a default constructor taking no arguments for the struct dont_care must exists so the user can write code like dont_care(). To get the example working i must write code like sumacc.result(*dont_care(0.0)*) to get the result from my accumulator. And this is a little bit unnecessary. with regards, Kim Tang the code below is tested with visual studio 2008. #include <iostream> #include <boost/accumulators/framework/accumulator_base.hpp> #include <boost/accumulators/framework/parameters/sample.hpp> using namespace boost::accumulators; namespace boost { // Putting your accumulators in the namespace accumulators { // impl namespace has some namespace impl { // advantages. See below. template<typename Sample> struct sum_accumulator // All accumulators should inherit from : accumulator_base // accumulator_base. { typedef Sample result_type; // The type returned by result() below. template<typename Args> // The constructor takes an argument pack. sum_accumulator(Args const & args) : sum(args[sample | Sample()]) // Maybe there is an initial value in the { // argument pack. ('sample' is defined in } // sample.hpp, included above.) template<typename Args> // The accumulate function is the function void operator ()(Args const & args) // call operator, and it also accepts an { // argument pack. this->sum += args[sample]; } result_type result(dont_care) const // The result function will also be passed { // an argument pack, but we don't use it here, return this->sum; // so we use "dont_care" as the argument type. } private: Sample sum; }; }}} int main() { try { boost::accumulators::impl::sum_accumulator<double> sumacc(sample=0.0); sumacc(sample=1.2); std::cout<<sumacc.result(*dont_care(0.0)*)<<"\n"; return EXIT_SUCCESS; } catch(std::exception& e) { std::cout<<"Errors with message: "<<e.what()<<"\n"; return EXIT_FAILURE; } catch(...) { std::cout<<"Unknown Errors \n"; return EXIT_FAILURE; } }

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[Iostreams] Can't open mapped_file data file on Windows
by Allen Cronce 03 Sep '08

03 Sep '08

Hi all, I'm trying to use mapped_file from the Boost 1.35.0 Iostreams library to open a data file for reading and writing. My code works fine under Mac OS X, which is posix, of course. But under Windows (built with VS2005), I get an access error. Here's a code sample that works on Mac OS X and fails under Windows: --snip-- /** Test boost iostream mapped_file. */ static int BoostMappedFileTest(void) { int result = 0; std::cout << "\nRunning BoostMappedFileTest..." << std::endl; // Initialize our test directory fs::path testDirPath( "BoostMappedFileTest" ); create_directory(testDirPath); // Initialize a test file buffer with some data const size_t kTestFileSize = 4096; boost::scoped_array<char> fileBuffer( new char[kTestFileSize] ); char* pCur = fileBuffer.get(); char curChar = 0; for( size_t i = 0; i < kTestFileSize; ++i ) { *pCur++ = curChar++; } // Write the data to a test file. Be sure to explicitly close it. fs::path testFilePath( testDirPath / "test_mapped_file" ); boost::filesystem::ofstream testFile( testFilePath, ios::trunc | ios::binary ); testFile.write(fileBuffer.get(), kTestFileSize); testFile.close(); // Try and open the test file as a memory mapped file. string testFilePathStr = testFilePath.file_string(); mapped_file mappedFile(testFilePathStr); // We never get here under Windows with boost 1.35.0. The file fails to // open with an access error, although it throws with a more obscure error // due to a clean up bug. // Compare the mapped file data to our original buffer const char* mmConstData = mappedFile.const_data(); bool compareSucceeded = (0 == memcmp(fileBuffer.get(), mmConstData, kTestFileSize)); if (!compareSucceeded) { throw runtime_error("The boost memory mapped file data doesn't match our buffer!"); } return result; } --snip-- The problem seems to come from passing GENERIC_ALL as the "dwDesiredAccess" parameter to the CreateFileA call. If I change the implementation to pass GENERIC_READ | GENERIC_WRITE, then it works in my test scenario. Please note that I haven't tried pointing the current code at an actual executable to see if it works with GENERIC_ALL. If you assume a strict interpretation of the mapped_file API, the mode of BOOST_IOS::in would map to GENERIC_READ in the Windows world, and BOOST_IOS::out would map to GENERIC_WRITE. There is no corresponding "execute" flag that I can see in this API. Since I'm only interested in mapping data files, I could certainly modify the boost 1.35.0 sources so that only GENERIC_READ and GENERIC_WRITE are passed to the Windows API depending on what BOOST_IOS mode was specified. But I'm not sure of what dependancies may exist between the mapped_file implementation and other boost libraries. The interprocess library, for example, hasn't yet fallen under my sphere of research ;-) Could someone please advise me as to the best course of action that will allow me to open memory mapped data files on Windows without adversely impacting the rest of the boost libraries? BTW, there's a secondary problem where if an error happens at CreateFileA, the clean up code fails and throws an invalid handle exception. This is because the mapped_handle_ member variable is initialized to NULL instead of INVALID_HANDLE_VALUE (which is what the clean up test is looking for). After code inspection of the svn trunk, I *think* this secondary issue has already been resolved. However, the latest sources look like they're still using GENERIC_ALL as the access parameter to the CreateFile, so my reported problem is still relevant and needs to be resolved. Thanks in advance for any suggestions. Best, -- Allen Cronce

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Bitset issue
by Sean Farrow 03 Sep '08

03 Sep '08

Hi: I am using a bitset to store up to 63 different values as a key in a mapp This does appear to be working though, as I carn't seem to get an iterator to accept any bitset even though it is defined, has any one go any othe ideas as to how I could tackle this issue. Regards Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3390 (20080826) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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Deployment of boost DLLs
by Ralf Globisch 03 Sep '08

03 Sep '08

Hi, I haven't been able to find much information on this, I hope someone can help me: I've only recently started using boost. I finally finished writing an application on my development machine. - Windows XP with Service pack 2 - Application developed in native C++ using MS VS2005 - Boost version 1.35, multithreaded, dynamically linked, installed boost using the installer from boost computing I then tried to deploy a release version of the application and the ms vc runtime redistributables to a test machine running a clean XP install and my application failed to run. The test machine also has XP Service Pack 2 installed. 1) To isolate the problem I then decided to start from scratch with a "Hello World" console application . Deployed it on the test machine and it ran fine. 2) Extended the console app to print out the current time using boost date time. Linked in boost dynamically by specifying BOOST_ALL_DYN_LINK. Deployed this on the server, received a "The application failed to initialize properly (0xc0150002) Click on OK to terminate the application" popup. 3) Rebuilt the application by changing the application to use a static runtime ( /MT instead of /MD ) Added the preprocessor directive BOOST_ALL_NO_LIB so that I could link to the static boost lib. Deployed the application on the server and it ran. 4) I then had a look at the dynamic boost release system DLL using depends.exe on the test machine: Strangely only the signal and the system DLL give the following error message: Error: The Side-by-Side configuration information for "c:\rtvc\bin\BOOST_SYSTEM-VC80-MT-1_35.DLL" contains errors. This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem (14001). The thread, date time, etc dlls are fine. However the signal and system dll are fine on my development machine. Has anyone encountered similar problems? Thanks, Ralf -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support.

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Re: [Boost-users] Boost and the .net framework
by raindog＠macrohmasheen.com 03 Sep '08

03 Sep '08

They are pretty much mutually exclusive to my knowledge. you can use them together of course but you would have to write custom marshallers for stl containers being passed to .net functions expecting arrays or ienumerable. ------Original Message------ From: Richard Miller Sender: boost-users-bounces(a)lists.boost.org To: boost-users(a)lists.boost.org ReplyTo: boost-users(a)lists.boost.org Sent: Sep 3, 2008 12:47 AM Subject: [Boost-users] Boost and the .net framework Can anyone tell me, are there issues using Boost with the .NET framework and managed C++? How would shared_ptr etc work? Are there issues with the collection classes? _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users Sent from my Verizon Wireless BlackBerry

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Compile errors with boost::mpl::if on MinGW/Msys
by Kevin Jenkins 03 Sep '08

03 Sep '08

Hi, I'm trying to use typedef typename boost::mpl::if_ to choose between two structures, both with identical function names, so I can choose which function to call based on the template parameter type. The code works fine on Visual Studio 2005. But in MinGW/MSys it returns: RPC3_Boost.h:203: error: template argument 2 is invalid RPC3_Boost.h:203: error: template argument 3 is invalid RPC3_Boost.h:203: error: ISO C++ forbids declaration of `type' with no type This is with boost_1_35_0. I've cut out as much code as I can: struct ReadBitstream { static void apply(RakNet::BitStream &bitStream, RakNet::BitStream* t) {/* ... */} }; template <typename T> struct ReadPtr { static inline void apply(RakNet::BitStream &bitStream, const char *&t) {applyStr(bitStream, (char *&) t);} }; template< typename T > struct DoRead { typedef typename boost::mpl::if_< boost::is_convertible<T*,RakNet::BitStream*>, typename ReadBitstream, typename ReadPtr<T> >::type type; }; To call the function, I use: DoRead< boost::remove_pointer<T>::type >::type::apply(* (args.bitStream),&t); Thanks in advance for any help. The whole file is here if you need to see more code: https://raknetjenkinsso.svn.sourceforge.net/svnroot/raknetjenkinsso/trunk/D…

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set help
by Kurt Kohler 03 Sep '08

03 Sep '08

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[Serialization] binary archive 1.75 times larger than source data
by Sebastian.Karlsson＠mmorpgs.org 03 Sep '08

03 Sep '08

Hi, So I've got most of my serialization working now, the only problem now is that it's still largely inefficent. The resulting binary file is 1.75 times larger than the sourcer XML file which I parse from. This is probably a lot due to the fact that I still default tracking and version everything. What I'd love to do however is to specify on a archive by archive basis if I want tracking / versioning. In fact, isn't this what one would normally want to do? When you specify tracking on a class by class basis you have no idea if there will be multiple pointer to the same object of that type. I found the no_tracking which I found a reference to from 2006 on this very mailing list, however it still doesn't seem to affect at least archive size ( haven't checked deserialization timings for it ). When I take a look at the deserialization the binary archive seems to store identifiers for types as their straight up string versions. This also seems largely inefficient, is there a reason for why this can't just be a hash? Also, is binary archives streaming or do they wait until the entire archive is loaded? Basically I'm wondering what would be the fastest possible archive one could create if one doesn't care about portability. // Sebastian Karlsson

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boost::filesystem: removing directory recursively?
by Ákos Maróy 03 Sep '08

03 Sep '08

Is there an easy / elegant way to remove directory contents recursively using boost::filesystem? I see that there's a create_directories() convenience function, but there's no such convenience function for removing a directory and all its contents. moreover, recursive_directory_iterator() does not return an iterator that contains the directory contens in the order suitable for removal :( I wonder if there's an easy / elegant way to do this? Akos

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[bind] [lambda] making lambda::bind work
by Peter Barker 03 Sep '08

03 Sep '08

Hello, I've got some code that works ok with boost::bind and I'm trying to make it work with lambda::bind but am getting compilation errors. Why not leave it as-is? Just above the problem area of code I have another lambda expression and because I've already introduced lambda's _1 placeholder into the current scope and didn't want ambiguities arising so want to convert it over. I'm using VC++ 7.1 (2003) and Boost 1.35.0. I've created a stripped down test program to show the compilation problem: #include <algorithm> #include <memory> #include <string> #include <vector> #include <boost/bind.hpp> #include <boost/utility.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> class GridItem : boost::noncopyable { public: bool AddOption(const char* item,bool unique = true) { // implementation code omitted! return true; } }; void GoodOldBoostBind() { std::auto_ptr<GridItem> item(new GridItem()); std::vector<std::string> options; std::for_each(options.begin(),options.end(), boost::bind(GridItem::AddOption,boost::ref(item),boost::bind(std::string::c_str,_1),true)); } void LambdaBind() { std::auto_ptr<GridItem> item(new GridItem()); std::vector<std::string> options; using namespace boost::lambda; using boost::lambda::_1; std::for_each(options.begin(),options.end(), bind(GridItem::AddOption,boost::ref(item),bind(std::string::c_str,_1),true)); // COMPILE ERROR ON ABOVE } int main() { } The error is: c:\releases\lib\boost\boost_1_35_0\include\boost\bind.hpp(338) : error C2664: 'R boost::_mfi::mf2<R,T,A1,A2>::operator ()<std::auto_ptr<_Ty>>(const U &,A1,A2) const' : cannot convert parameter 2 from 'boost::lambda::lambda_functor<T>' to 'const char *' with [ R=bool, T=GridItem, A1=const char *, A2=bool, _Ty=GridItem, U=std::auto_ptr<GridItem> ] and [ T=boost::lambda::lambda_functor_base<boost::lambda::action<2,boost::lambda::function_action<2>>,boost::tuples::tuple<const boost::lambda::detail::bind_traits<const char *(__thiscall std::basic_string<char,std::char_traits<char>,std::allocator<char>>::* const )(void) const>::type,const boost::lambda::detail::bind_traits<const boost::lambda::placeholder1_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type,boost::lambda::detail::bind_traits<boost::tuples::null_type>::type>> ] No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called Can anyone help with this? Thanks, Pete

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