September 2010 - Boost - lists.boost.org

[filesystem] Link errors on Linux/MacOS with v3
by cheesy4poofs 21 Sep '10

21 Sep '10

I've gone thru the exercise of converting all our code to use filesystem v3. Everything worked fine on Windows, but when I tried to compile on Linux and Mac, I get link errors with gcc. I have set my compiler flags to -DBOOST_FILESYSTEM_VERSION=3 and everything compiles fine. All the link errors come from filesystem3: ../NwUtils/libNwUtils.a(FileStream.cpp.o): In function `boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)': FileStream.cpp:(.text._ZN5boost11filesystem34path6appendIA12_cEERS1_RKT_RKSt 7codecvtIwc11__mbstate_tE[boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)]+0x30): undefined reference to `boost::filesystem3::path::m_append_separator_if_needed()' FileStream.cpp:(.text._ZN5boost11filesystem34path6appendIA12_cEERS1_RKT_RKSt 7codecvtIwc11__mbstate_tE[boost::filesystem3::path& boost::filesystem3::path::append<char [12]>(char const (&) [12], std::codecvt<wchar_t, char, __mbstate_t> const&)]+0x59): undefined reference to `boost::filesystem3::path::m_erase_redundant_separator(unsigned long)' Am I supposed to compile boost with a different setting to use filesystem v3? I didn't do anything special on windows. When I attempt to build boost on Mac/Linux with -DBOOST_FILESYSTEM_VERSION=3, the boost build fails with errors about BOOST_FILESYSTEM_VERSION != 2. Any help would be greatly appreciated as I'm at my wit's end! Thanks, Scott

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[B-tree] Preliminary timings
by Beman Dawes 20 Sep '10

20 Sep '10

See http://mysite.verizon.net/beman/btree/preliminary_timings.html Notice that under some test conditions, some operations are faster on a btree_map than a std::map. But do be aware that these timings are preliminary. Bugs in either the test code or the implementation code could be skewing results. The test program can be viewed at http://github.com/Beman/Boost-Btree/blob/master/libs/btree/tools/bt_time.cpp Comments appreciated! --Beman

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[chrono] Split into Stopwatches, Chrono, Ratio and TypeTraits.ext
by vicente.botet 20 Sep '10

20 Sep '10

Hi, As requested in this ML I have splited Boost.Chrono into 4 libraries * Boost.TypeTraits.Ext: contains the C++0x common_type and add_rvalue reference traits classes and the declval utility function * Boost Ratio: contains the C++0x ratio class * Boost.Chrono: contains the C++0x chrono library + process and thread clocks * Boost.Stopwatches: time measure and reporting More information on these libraries can be found in https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Type… https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Ratio https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Chro… https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Stop… Please let me know if you prefer separated reviews for each library. Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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Connection refused after close then open
by Doak, Roger (GE Healthcare) 20 Sep '10

20 Sep '10

Hi I'm trying to limit the connections made to the server. So after creating the acceptor and accepting MAX connections I closed the acceptor. If there is a better way please let me know. Further connections are properly rejected. However after one of the connections is closed by the client I attempt to re-open the acceptor but further connections are still rejected? Create and open: m_acceptor(m_ioService, m_endpoint = resolve(m_ioService, host, port), true) Async accept: m_acceptor.async_accept(connection->socket(), boost::bind(&IpServer::handleAccept, this, aph::error, connection)); Close after max connections: m_acceptor.close(); Reopen when a connection is available: m_acceptor.open(m_endpoint.protocol()); m_acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true )); m_acceptor.bind(m_endpoint); m_acceptor.listen(); m_acceptor.async_accept(connection->socket(), boost::bind(&IpServer::handleAccept, this, aph::error, connection)); Thank you for your time. Roger

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[Locale] Link errors
by Alexander Lamaison 20 Sep '10

20 Sep '10

I'm getting link errors with the latest Boost.Locale (v2.91) when trying to use the Win32 backend: [ 34%] Building CXX object CMakeFiles/boost_locale.dir/libs/locale/src/win32/win _backend.cpp.obj win_backend.cpp Linking CXX shared library boost_locale.dll Creating library boost_locale.lib and object boost_locale.exp win_backend.cpp.obj : error LNK2019: unresolved external symbol "unsigned int __ cdecl boost::locale::impl_win::locale_to_lcid(class std::basic_string<char,struc t std::char_traits<char>,class std::allocator<char> > const &)" (?locale_to_lcid @impl_win@locale@boost@@YAIABV?$basic_string@DU?$char_traits@D@std@@V?$allocator @D@2@@std@@@Z) referenced in function "public: __thiscall boost::locale::impl_wi n::winlocale::winlocale(class std::basic_string<char,struct std::char_traits<cha r>,class std::allocator<char> > const &)" (??0winlocale@impl_win@locale@boost@@Q AE@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) boost_locale.dll : fatal error LNK1120: 1 unresolved externals I configured CMake as such: boost_locale_v2.91>cmake -G "NMake Makefiles" -DDISABLE_ICU=ON -DDISABLE_STD_BACKEND=ON -DCMAKE_INCLUDE_PATH="C:\boost" Where Boost is version 1.42. This is on Windows 7 32-bit. Any ideas? Alex -- Easy SFTP for Windows Explorer (http://www.swish-sftp.org)

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[Review] Formal Review: Boost.Move
by OvermindDL1 19 Sep '10

19 Sep '10

Greetings Boost Developers and Users, It's my pleasure to announce that the review of Ion Gaztañagas' Move library starts May 10th and lasts until May 24th, 2010, unless an extension occurs. What is it? =========== The Boost.Move library would supply an emulated C++1x Move semantics interface, aka RValue References, allowing for a wide variety of easy to use and easy to add in optimization abilities. The most used function it would add would be: val_b = boost::move( val_a ); Which would move val_a to val_b; val_a should not be used after this line. This semantic allows for a vast amount of optimizations, especially in regards to temporaries, see the documentation for further examples and use. Other patterns emulated are && rvalue references for functions/members and constructors. There are also a number of STL containers in the sandbox that support move semantics using this library for higher efficiency. Getting the library =================== The latest version of this library may be downloaded from SVN: http://svn.boost.org/svn/boost/sandbox/move/ and the docs may be viewed here Docs: http://igaztanaga.drivehq.com/libs/move/doc/html/index.html and do note, this library is header-only and is designed to be absolutely generic to be useful in all areas of C++ programming. Writing a review ================ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ====================== If you want or need a primer on the subject, please look at the working draft for C++1x. This linked site has also been shown to be quite useful in describing move usefulness: Want Speed? Pass by Value.: http://cpp-next.com/archive/2009/08/want-speed-pass-by-value/ Move It With Rvalue References: http://cpp-next.com/archive/2009/09/move-it-with-rvalue-references/ And there are further links in that series, but those two will get you started in the domain. Best regards, OvermindDL1, Review Manager (Boost.Move)

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Re: [boost] [serialization] Must the objects being serialized outlive the archive?
by Chris Yuen 18 Sep '10

18 Sep '10

Jeff Flinn wrote: > IIUC, tracked objects have their addresses place in a map, so that > subsequent serialized pointers of the same value are serialized as a > reference to the original object at that address, rather than > serializing another copy of the object. That was spot on! I did a couple of tests and I think I've confirmed this is indeed the behavior and the reason why data gets corrupt. On my platform (MSVC), new data gets allocated to the last free pointer's address and that confuses boost::serialization. >From your understanding, doesn't that basically means the "objects being serialized must outlive the archive"? Since there's no way to tell "new" to not allocate objects at an older address unless I keep objects there. So basically I must keep all data in memory until the serialization process is complete. I tried to think hard about this. Do you see any workaround to this issue so that I don't have to effectively double the memory usage? (Maybe have boost::serialization write things out immediately and clear the internal cached pointers)? Maybe boost::serialization should provide that command or some kind of "flush" command? Best regards, Chris Yuen

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[function] Question on semantics of boost::function
by David Sankel 18 Sep '10

18 Sep '10

Is a boost::function<void (int)> semantically different from a boost::function<void (int &)> or a boost::function<void (const int)>? David -- David Sankel Sankel Software www.sankelsoftware.com 585 617 4748 (Office)

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Re: [boost] [serialization] Must the objects being serialized outlive the archive?
by Brian Wood 17 Sep '10

17 Sep '10

Robert Ramey: > This would work. What won't work is > > { > boost::scoped_ptr<Strings> s; > const Strings * s = new Strings("Hello", "World")); > const * x = s; > oa << s; > delete s; > oa << x; > ... > } Be sure to add the --automagically flag to get that to build. > Your making this way too hard, just look at the examples and tests to see > that all you have to do is serialize though a base class pointer. You are being sloppy. But thanks for stopping the top posting. Brian Wood Ebenezer Enterprises http://webEbenezer.net

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Re: [boost] [serialization] Must the objects being serialized outlive the archive?
by Chris Yuen 17 Sep '10

17 Sep '10

Robert, > It is a fundamental concept that saving data to an archive should > not alter the data. In many cases this is detected at compile time > and a warning is issued. As noted in another post, you might > snooker the system by suppressing tracking, I don't really understand. Why does the tracking has something to do with the object's lifetime? Doesn't boost::serialization has all the information it needs (tracking info, data, etc.) when I call "oa << base_ptr"? Isn't it possible to just write out everything to the stream? > But I'm intrigued why you want to do this? Why don't you just use > { > std::ofstream stream(kFilename, std::ios::binary); > boost::archive::text_oarchive oa(stream); > > { > const Strings s("Hello", "World")); > oa << s > } > ... > } As you can see from the code example, I want to be able to deserialize a list of these "commands" from the base pointer, because I actually have hundreds of these polymorphic commands and they need to each have a virtual "Execute()" method so that they know how to apply themselve to an "Actioner." (Instead of using a giant switch-case in the Actioner to identify each command) I figured it's better than using a magic number, opcode approach since boost::serialization already provides tracking. I was under the impression that if I want to deserialize using a base pointer, I must also serialize via the base pointer, is that correct? So I guess the below won't work with the original deserialization code? > { > boost::scoped_ptr<Strings> s; > const Strings * s = new Strings("Hello", "World")); > oa << s; > .... // same for all the other stuff > // s deleted as it goes out of scope > } Best regards, Chris Yuen

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