May 2010 - Boost - lists.preview.boost.org

Multicore-BGL
by Giorgio Zoppi 31 May '10

31 May '10

Hi, we're intersted in how to optimize BGL on Multicore for adding our standard Bellman-Ford algorithms for optical networks. How do the current boost work on Multicore? BGL is thread-safe? Which parts are required to optimize? Cheers, Giorgio. -- Quiero ser el rayo de sol que cada día te despierta para hacerte respirar y vivir en me. "Favola -Moda".

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boost::log access violation with global objects destructors
by Philippe Vaucher 31 May '10

31 May '10

Hello, Boost.Log creates an access violation when global objects being destructed attemps to log something. The doc says that I have to keep a shared_ptr to the core, but even doing so doesn't seem to work. I created a simple testcase here: http://codepad.org/pr8fAiZ2 The access violation location changes when the code change so I'm not sure how to handle this. This happens on Windows XP with boost 1.43 and the latest boost.log source from the svn. Thanks in advance! Philippe

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[multiindex] internal scope_guard has changed access from public to protected
by Thorsten Ottosen 31 May '10

31 May '10

Hi Joaquín, I'm using the scope_guard from multi_index/detail/scope_guard.hpp. It seems like a revision has made the destructor and copy-constructor protected instead of private. This is in some sense more idiomatic, but it breaks a use that I have in my upcomming auto_buffer class. Basically I'm only constructing a scope_guard object when I know the code can throw, otherwise I construct a "null" scope_guard which is simply an instance of scope_guard_impl_base. Here's the code: namespace auto_buffer_detail { typedef boost::multi_index::detail::scope_guard_impl_base null_guard; } #define BOOST_AUTO_BUFFER_CONSTRUCTOR_SCOPE_GUARD() \ boost::has_nothrow_copy<T>::value ? boost::auto_buffer_detail::null_guard() : \ boost::multi_index::detail::make_obj_guard( *this, \ &auto_buffer::deallocate, \ buffer_, members_.capacity_ ) and use it like so: boost::multi_index::detail::scope_guard guard = BOOST_AUTO_BUFFER_CONSTRUCTOR_SCOPE_GUARD(); ... guard.dismiss(); Any chance you make the two members public again? -Thorsten

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Boost related events calendar
by vicente.botet 30 May '10

30 May '10

Hi, In http://www.boost.org/development/index.html, the section "Release Schedule" contains much more "Boost related events", maybe we can change the title. BTW, the release schedule for 1.44.0 is missing. Will the Bug Spring Week take place (June 5-13th)? If yes, can someone having the rights add this to the calendar? Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[system] Heads up: Breaking changes
by Beman Dawes 30 May '10

30 May '10

Changeset 62313 brings Boost.System into closer conformance with the C++0x working paper (and FCD) with regard to the system_category and generic_category interface. Because system_category and generic_category change from constants to functions returning references, this is a breaking change. The fix is to change uses of "system_category" to "system_category()", and "generic_category" to "generic_category()". See https://svn.boost.org/trac/boost/changeset/62313 AFAIK, the only Boost library this change breaks is filesystem. The changeset includes fixes for it. Asio also uses System, but in a way that does not break AFAICT. Before committing the change, I tested system, filesystem, and asio locally on Windows and Linux. But given the possibility of unintended consequences, I thought a heads up to the list might be useful. I'll try to keep a close eye on regression tests as they cycle, but if anyone has any problems, please let me know. Thanks, --Beman

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[move] problem with msvc and BOOST_MOVABLE_BUT_NOT_COPYABLE
by Oliver Kowalke 30 May '10

30 May '10

I get an linker error (private: __thiscall X::X(class X &) is unresolved symbol) with msvc-9.0 on XP. AFAIL (docu) implementing the copy-ctor isn't required and passing values from static memeber functions are allowed. What's wrong? Oliver #include "stdafx.h" #include <boost/move/move.hpp> class X { private: BOOST_MOVABLE_BUT_NOT_COPYABLE( X); public: X(); static X create(); X( BOOST_RV_REF( X) other); X & operator=( BOOST_RV_REF( X) other); }; X::X() {} X X::create() { X x; return x; // passing value form static memeber-fn } X::X( BOOST_RV_REF( X) other) {} X & X::operator=( BOOST_RV_REF( X) other) { return * this; } int _tmain(int argc, _TCHAR* argv[]) { X x( X::create() ); return 0; } -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01

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https://svn.boost.org: SSL negociation failed
by vicente.botet 29 May '10

29 May '10

Hi, I'm getting this error while trying to commit Commit Commit failed (details follow): OPTIONS of 'https://svn.boost.org/svn/boost/sandbox/chrono/boost/chrono': SSL negotiation failed: SSL error: unknown protocol (https://svn.boost.org) I get the same error while I try to connect to https://svn.boost.org. Telling that the SSL version is is an old non secured one. Have others the same error or is just a problem in my configuration? Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[endian] Use in Hash algorithms
by Scott McMurray 29 May '10

29 May '10

Popular hash algorithms (MD5, SHA, ...) involve a preprocessing stage to turn bytes (or individual bits) into (32- or 64-bit) words, using a certain byte (and bit) order. For my Hash library, I ended up writing a pack function that takes an endianness and the number of bits in the input and output values, and combines or splits the input as needed. A simple example: { array<uint8_t, 8> in = {{0x67, 0x45, 0x23, 0x01, 0xEF, 0xCD, 0xAB, 0x89}}; array<uint32_t, 2> out; pack<little_octet_big_bit, 8, 32>(in, out); array<uint32_t, 2> eout = {{0x01234567, 0x89ABCDEF}}; assert(out == eout); } As a bonus, it also handles non-bytes units: { array<uint8_t, 3> in = {{31, 17, 4}}; array<uint16_t, 1> out; pack<big_bit, 5, 15>(in, out); array<uint16_t, 1> eout = {{(31 << 10) | (17 << 5) | (4 << 0)}}; assert(out == eout); } An extensive set of examples can be found here: <http://svn.boost.org/svn/boost/sandbox/hash/libs/hash/test/pack.cpp> This is used to turn the input into words, to turn the length into words for padding, for figuring out where in the word the "1" padding bit goes, and for turning the state back into octets for display. There are enough optimizations SFINAEed in that the first example just results in a memcpy on x86, but doesn't require contiguous input. (It's perfectly happy with single-pass input, though usually somewhat slower in that case.) I'm not sure how widely applicable this form of the solution would be, but I think it's a case where both the byte-swapping version and Beman's swap-on-load approach are awkward. ~ Scott McMurray

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[log] unspecified error when going from win7 to xp
by Christoph Heindl 29 May '10

29 May '10

Hi, forgive me if the following error description is too vague. We are currently using boost.log (exported on 2010/05/20, compiled with msvc 9.0 sp1 on win7 against boost 1.40.0) in a large C++ project. On top of this C++ project a C-API is placed to ease integration with .NET's pInvoke technology. This C-API consists of very primitive methods. Integration with .NET (2.0 or 3.x does not matter) works fine on win7. But when the executables are moved to a windows xp (or lower) based platform (with all redistributables installed) it breaks with an AccessViolationException. We tracked down the problem (without the ability to debug :) to the usage of BOOST_LOG_FUNCTION and/or BOOST_LOG_NAMED_SCOPE. If those macros are not used, everything works fine again. I know my description is vague, but maybe someone has an idea if the problem is us or the problem could rely in those macros. Help is desperately needed. Best regards, Christoph

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Is there any interest in Boost.Conversion?
by vicente.botet 29 May '10

29 May '10

Hi, The Boost.Conversion library (Generic explicit conversion between unrelated types) has not revealed too much interest for the Boost community since v0.4 was released on 10/09. For those that don't know it yet you can get the documentation and download links from https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Conv… I have added on the sandbox some pending issues that Jeffrey Hellrung related to conversions that need extra information. If B1 is covertible to A1 using convert_to, now we can conver vectors of conversible types. B1 b10, b11, b12, b13; std::vector<B1> vb2; vb2[0]=b10; vb2[1]=b11; vb2[2]=b12; vb2[3]=b13; std::vector<A1> va2(boost::convert_to<std::vector<A1> >(vb2)) std::vector<A1,std::allocator<A1> > va6( boost::convert_to<std::vector<A1,std::allocator<A1> > >(pack(vb2, std::allocator<A1>()))); Note that when the Target constructor has some arguments (as is the case for vector with a specific allocator) we pack the Source and the Target arguments in a pack. The first argument is the Source. boost::conversion::pack(vb2, std::allocator<A1>()) The function 'pack' is currently a little bit rudimentary, but is usable already for vector conversions using a specific allocator. Currently accepts only two parameters, I plan to go up to 5 parameters. Any suggestion for better namming 'boost::conversion::pack'. I have no solution for the ambiguity problem of a user getting two different overloads of the same conversion on different namespaces, other than suggesting that convert_to overloadings should be done on the namespace of the Source, for example. Jeffrey does this answer to your attends? I will release the pack function and vector conversion (v.0.5) on the Vault once I will update the documentation. Comments are welcome :) Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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