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Re: [Boost-users] wide-char version of boost::mapped_file?
by Tan, Tom (Shanghai) 26 May '09

26 May '09

By borrowing code from boost::filesystem V3, I re-implemented the to_string function like this: std::string to_string(const wstring& ws) { const size_t BUFFER_SIZE = (ws.size() << 1) + 1; shared_array<char> p_mcb(new char[BUFFER_SIZE]); int count = ::WideCharToMultiByte( AreFileApisANSI() ? CP_THREAD_ACP : CP_OEMCP, WC_NO_BEST_FIT_CHARS, ws.c_str(), ws.size(), p_mcb.get(), BUFFER_SIZE, 0, 0 ); return (-1 == count) ? std::string() : std::string(p_mcb.get(), count ); } This seems to have solved the conversion problem. Is it possible to add an overloaded constructor based on this code to take std::wstring or just take a boost::path when V3 comes out.? It would ease the usage a lot in my opinion. -----Original Message----- From: Tan, Tom (Shanghai) Sent: 2009-05-26 11:55 To: 'boost-users(a)lists.boost.org' Subject: wide-char version of boost::mapped_file? I am trying to use boost::mapped_file in the iostream library. While I like the interface. The fact that it only supports the ANSI version of windows API, thus dictating an ANSI version of file path, really drives me crazy. In my code I use std::wstring everywhere. Because boost::mapped_file asked for a std::string to construct like this: explicit mapped_file( const std::string& path, std::ios_base::openmode mode = std::ios_base | std::ios_base, size_type length = max_length, boost::intmax_t offset = 0 ); I wrote a small routine to convert it like this: std::string to_string(const wstring& ws) { const size_t BUFFER_SIZE = (ws.size() << 1) + 1; shared_array<char> p_mcb(new char[BUFFER_SIZE]); setlocale( LC_ALL, ".2052"); size_t count = wcstombs(p_mcb.get(), ws.c_str(), BUFFER_SIZE ); return (-1 == count) ? std::string() : std::string(p_mcb.get()); } It does not really work well when I have Enlish and Chinese characters mixed together in the path, while it does for pure Chinese paths. So I traced down to the source code to find out why a std::string instead of basic_string<Char> is needed, anyway, it's just a path, and has nothing to do with mapping it does. There seems to be no clue except for the ANSI version of Win32 APIs, which actually have wide-char versions. Did I missing any design requirement that force it to be like what it is today? Another issue is, it throws exception from inside the constructor when it tries to map a zero-length file. IMHO, it's not good to throw for a legal file, be its length zero, and not good to throw from the constructor either.

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wide-char version of boost::mapped_file?
by Tan, Tom (Shanghai) 26 May '09

26 May '09

I am trying to use boost::mapped_file in the iostream library. While I like the interface. The fact that it only supports the ANSI version of windows API, thus dictating an ANSI version of file path, really drives me crazy. In my code I use std::wstring everywhere. Because boost::mapped_file asked for a std::string to construct like this: explicit mapped_file( const std::string& path, std::ios_base::openmode mode = std::ios_base | std::ios_base, size_type length = max_length, boost::intmax_t offset = 0 ); I wrote a small routine to convert it like this: std::string to_string(const wstring& ws) { const size_t BUFFER_SIZE = (ws.size() << 1) + 1; shared_array<char> p_mcb(new char[BUFFER_SIZE]); setlocale( LC_ALL, ".2052"); size_t count = wcstombs(p_mcb.get(), ws.c_str(), BUFFER_SIZE ); return (-1 == count) ? std::string() : std::string(p_mcb.get()); } It does not really work well when I have Enlish and Chinese characters mixed together in the path, while it does for pure Chinese paths. So I traced down to the source code to find out why a std::string instead of basic_string<Char> is needed, anyway, it's just a path, and has nothing to do with mapping it does. There seems to be no clue except for the ANSI version of Win32 APIs, which actually have wide-char versions. Did I missing any design requirement that force it to be like what it is today? Another issue is, it throws exception from inside the constructor when it tries to map a zero-length file. IMHO, it's not good to throw for a legal file, be its length zero, and not good to throw from the constructor either.

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Re: [Boost-users] [Serialization] Guard against attempting to deserialize the wrong type
by Dan Eaton 25 May '09

25 May '09

Actually, it doesn't seem to be doing any check... looking at the contents of the XML emitted, the name is definitely different than the one I'm requesting. oarchive << BOOST_SERIALIZATION_NVP(foo); iarchive >> BOOST_SERIALIZATION_NVP(bar); This works fine where foo & bar are the same type (using xml_iarchive / oarchive) Am I doing something wrong? From: Dan Eaton Sent: Monday, May 25, 2009 1:30 PM To: 'boost-users(a)lists.boost.org' Subject: [Serialization] Guard against attempting to deserialize the wrong type Hello, I'm just wondering if NVP/XML archives check the name during deserialization? I just had a problem whereby I tried deserializing an object to one type, but the archive actually contained a different (larger ) object type. The first serialized element of the object just so happened to be an unsigned int, and I was trying to deserialize an enum, so the output actually seemed sensible, and didn't cause any problems until I later deserialized the full object from the same archive, which caused a segmentation fault in the boost::serialize source (trying to get ETI from a null pointer). I was using a polymorphic text archive, and as I mentioned above, am wondering if I switched to an XML archive if this sort of user-error would be detected. Thanks, Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[Serialization] Guard against attempting to deserialize the wrong type
by Dan Eaton 25 May '09

25 May '09

Hello, I'm just wondering if NVP/XML archives check the name during deserialization? I just had a problem whereby I tried deserializing an object to one type, but the archive actually contained a different (larger ) object type. The first serialized element of the object just so happened to be an unsigned int, and I was trying to deserialize an enum, so the output actually seemed sensible, and didn't cause any problems until I later deserialized the full object from the same archive, which caused a segmentation fault in the boost::serialize source (trying to get ETI from a null pointer). I was using a polymorphic text archive, and as I mentioned above, am wondering if I switched to an XML archive if this sort of user-error would be detected. Thanks, Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[ASIO / Serialization] How to avoid the copy?
by Dan Eaton 25 May '09

25 May '09

Hello, Referring to the boost::asio "Serialization" example, and specifically to the file connection.hpp which handles serialization over sockets: http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/example/serializat… When new data is to be received, first the message header is read, which contains the number of bytes for the body. Storage must be allocated to receive the body, and is then passed into ::read as boost::asio::buffer. For the purpose of using Serialize, it must then be converted to an std::istream, (in the example above, istringstream). As shown in the example, this requires an extra copy to be held in memory for the std::string. What's the best route to avoid this copy? Thanks, Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[ASIO / Serialization] How to avoid the copy?
by Dan Eaton 25 May '09

25 May '09

Ah, yes, it looks like it does have something like that (an implementation of streambuf). Thanks! Dan Eaton Software Developer Acceleware Corp. (TSX-V:AXE) www.acceleware.com<http://www.acceleware.com/> Phone: +1.403.249.9099 Ext.295 Fax: +1.403.249.9881 Email: daniel.eaton(a)acceleware.com<mailto:daniel.eaton@acceleware.com> Get superpowered! Acceleware gets your products to market faster, better and stronger! This e-mail may contain information that is privileged and confidential and subject to legal restrictions and penalties regarding its unauthorized disclosure or use. You are prohibited from copying, distributing or otherwise using this information if you are not the intended recipient. If you have received this e-mail in error, please notify us immediately by return e-mail and delete this e-mail and its attachments from your system. Thank you. (c) 2008 Acceleware, Inc. All Rights Reserved

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[serialization] appending to an archive
by hurcan solter 25 May '09

25 May '09

I am trying to append one or more records to the existing archive file, using something like this; void Logger::save(const std::string& fileName) { assert(fileName != "logger.dmp"); bp::time_duration endRecordTime = getCurrentTime(); ofs.flush(); path dst = complete(path(fileName, native)); path src = complete(path("logger.dmp", native)); remove(dst); copy_file(src, dst); ofstream saveFile(dst,std::ios::app); ArchiveType archive(saveFile,boost::archive::no_header); *mArchive << endRecordTime } although i specify no_header flag, it inserts a '0' as a preamble, how can i turn it off? have you guys ever needed to use serialization like this? what was your solution Thanks in advance Hurcan

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[Container] ptr_set with user define compare function
by 梁绍池 25 May '09

25 May '09

I've defined a function object as below: struct BaseAddrLess : public std::binary_function<Base, Base, bool> { result_type operator() (const first_argument_type& lhs, const second_argument_type& rhs) const { return &lhs < &rhs; } }; and use as a compare function in ptr_set like this: ptr_set<Base, BaseAddrLess> bset; when the class Base is a abstract class the vc9 compiler will complain use of undefined type 'boost::result_of<F>' What causes this problem? How to solve it? Thank you for your patience to read my poor english. S.C. Leung

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exception: use of error_info can mask real exceptions
by Andrew Venikov 25 May '09

25 May '09

Just wanted to ask if there were commonly accepted solutions to the following problem: typedef boost::error_info<struct tag_f1, std::string> f1_descr; and then throw f1exception() << f1_descr("blah blah blah"). and later catch(f1exception & ex){...} The constructor of std::string may throw an exception in which case f1exception will never be thrown. This is not necessarily the desired outcome as the intention was obviously to indicate f1exception error, not the string() error. This problem pertains to any type that throws exceptions in its constructor and is used with error_info idiom. What may be more appropriate is something like this typedef boost::error_info<struct tag_f1, shared_pointer<string> > f1_descr ... error condition is detected shared_ptr<string> pErrStr; try { pErrStr = new string("Error description"); } catch(bad_alloc & ex) { } throw f1exception() << f1_descr(pErrStr); Meaning that if string fails to allocate memory, I'm willing to forgo the error description but still throw the intended exception. Is there a cleaner way to do that? Thanks, Andy.

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boost::thread_specific_ptr
by jono 25 May '09

25 May '09

hi all, i'm using thread_specific_ptr (boost 1.33.1, sorry) in a plugin architecture, where the tls identifies a singleton object of type Context (initialized using DCLP). boost::thread_specific_ptr<Context> Context::instance_; i also have a set of shared libraries and a main executable linked against a static library defining the Context class. this all works fine so long as the libraries are loaded and the threads created in that order, however, if a library is loaded after thread is started, then the thread_specific_ptr in that thread appears to be reset to null, without calling cleanup(). if i use the debugger to inspect the singleton ptr before and after loading the second module, it is, before: $1 = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_tss = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_slot = 8}} ..and after: $2 = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_tss = {<boost::noncopyable_::noncopyable> = {<No data fields>}, m_slot = 1}} is this correct behaviour for thread_specific_ptr? is there a way i can obtain a handle for the first Context object before it is destroyed? here's some info about my system. $ cat /proc/cpuinfo ... AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ ... $ uname -a Linux lumpen 2.6.19 #2 SMP Fri Jan 12 17:58:33 NZDT 2007 x86_64 x86_64 x86_64 GNU/Linux $ gcc -v Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux Thread model: posix gcc version 4.1.1 20060525 (Red Hat 4.1.1-1) any help would be appreciated. cheers, Jono

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