May 2009 - Boost - lists.preview.boost.org

release notes for 1.39.0?
by Neal Becker 18 May '09

18 May '09

Where can I find some more detailed release notes? I looked here: http://comments.gmane.org/gmane.comp.lib.boost.announce/233

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[serialization] Enum loading may lead to uninitialized value [Ask for change]
by Andrey Upadyshev 18 May '09

18 May '09

Hi! I found that template boost::archive::detail::load_enum_type (boost\archive\detail\iserializer.hpp) may overvrite loading enum's value with uninitialized ones. See comments: template<class Archive, class T> struct load_enum_type { static void invoke(Archive &ar, T &t){ int i; // Initialize 'i' with trash ar >> boost::serialization::make_nvp(NULL, i); // Imagine: some code in archive skips loading t = static_cast<T>(i); // Ooops, get the trash into 't' } }; I think it is more secure to initialize 'i' from 't'. So, if archive's code skips loading, we just get 't' unchanged instead of corrupted. Probably, someone can fix this in svn? Andrey Upadyshev P.S. Sorry for my English.

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[regex] patch for Sun CC
by Steven Watanabe 18 May '09

18 May '09

AMDG To get regex to work with Sun 5.9, I had to add std:: in one place. Most of the tests pass, but a few still fail for mysterious reasons. Okay to commit? In Christ, Steven Watanabe

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[boost1.38][serialization][Patch Request] Request a patch for fixing crashes on SunOS 64bit platform
by Joanne chiang 18 May '09

18 May '09

Hi, Please consider : 1. fixing the regression issues (iostream error/exception, segmentation faults , illegal instruction etc.) happened when running the testsuite bundled with boost.serilation (v1.38, though I believe it applies to other revisions) on SunOS 5.8 sparc v9 (5.9, 5.10 64-bit also get the same crashes). 2. adding SunOS 64bit platform to the boost regression test trunk : http://www.boost.org/development/tests/trunk/developer/serialization.html ,if possible. Thanks very much, Mave

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Re: [boost] [filesystem] copy_file() not atomic proposed fix
by Beman Dawes 17 May '09

17 May '09

On Fri, May 15, 2009 at 5:10 AM, Andre Merzky <andre@...> wrote: > Quoting [Beman Dawes] (May 12 2009): >> >> Ticket #2925 complains that "boost::filesystem cannot atomically copy >> file if target exists" ... >> >> ... >> >> The proposed solution is to add an option to copy_file(): >> >> enum class copy_option { fail_if_exists, overwrite_if_exists }; >> >> void copy_file( const Path & from_path, const Path & to_path, >> copy_option option=copy_option::fail_if_exists ); >> >> The implementation would be atomic on both POSIX and Windows. >> >> Comments? > > Makes sense. OK, fix committed to trunk. It will go in branches/release once sufficient regression tests have cycled. > I would suggest to check the complete lib for similar > problems. I think most operational and convenience > functions are prone to similar problems. Hum... "most" is too strong; many of the operational functions are implemented as a single operating system API call. I really don't want to spend time analyzing and fixing the V2 codebase. Instead, I've added an item to the V3 do-list to do an atomicity review. I'm planning to spend a lot of time on Filesystem.V3 this summer, and release a V3 beta as the code firms up. Thanks, --Beman

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PropertyTree's XML parsers survey
by Sebastian Redl 17 May '09

17 May '09

Hi, PropertyTree currently has 5 (five!) different xml readers using 4 different parsers. I don't want to maintain them all. Looking at the open tickets for PT shows that most bugs occur in the various xml readers, and there's no point in having more than one. I just wonder which one to keep. To those who use PropertyTree's XML format, which parser do you use? Do you have any experience with the pros and cons of the various parsers? All feedback is highly appreciated. Sebastian

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[test] Boost.Test with Sun CC
by Steven Watanabe 17 May '09

17 May '09

AMDG The attached patch allows the library to build with Sun 5.9. In Christ, Steven Watanabe

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aligned storage problems with borland
by Robert Ramey 17 May '09

17 May '09

Serialization tests indicated that a recent change to aligned storage has broken serialization tests for borland. Could someone please look into this? Error E2031 ..\boost/aligned_storage.hpp 126: Cannot cast from 'aligned_storage<4,8> * const' to 'detail::aligned_storage::aligned_storage_imp<4,8> *' in function aligned_storage<4,8>::address() *** 1 errors in Compile *** Robert Ramey

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[test] Using the Boost Unit Test Framework with shared libs
by Peter 17 May '09

17 May '09

Hi I am using Boost.Test from the current boost 1.38 , on cygwin ( gcc ) and I want to use it with multiple test files and with shared libs ( in order to speed up the compilation time which is too long for me when using the header include variant ). What is the recommended way ? ( I read the doc, several times and I read the _long_ threads on the mailing list concerning the static/shared library issue, but I am not sure that I understood all the details). I did the following: *in mainTest.cpp:* #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MAIN #include "../inc/globalFixture.hpp" #include "../inc/testfile1.hpp" #include "../inc/testfile2.hpp" *testfile1.hpp:* #include "globalFixture.hpp" BOOST_FIXTURE_TEST_SUITE(ATlib1, Fixture) BOOST_AUTO_TEST_CASE(Resource_Manager) { ... ....BOOST_CHECK .... } BOOST_AUTO_TEST_SUITE_END() *testfile2.hpp:* #include "globalFixture.hpp" BOOST_FIXTURE_TEST_SUITE(ATlib2, Fixture) BOOST_AUTO_TEST_CASE(FileManager { ... BOOST_CHECK .... } BOOST_AUTO_TEST_SUITE_END() *globalfixture.hpp: *#ifndef _GLOBALFIXTURE_HPP #define _GLOBALFIXTURE_HPP #define BOOST_TEST_MODULE ATlib #include <iostream> #include <boost/test/unit_test.hpp> #include <boost/test/detail/unit_test_parameters.hpp> #include <boost/bind.hpp> #include <boost/test/output_test_stream.hpp> using namespace boost::unit_test; struct GlobalConfig { GlobalConfig() { std::cout << "GlobalConfig setup\n"; using namespace boost::unit_test; if (runtime_config::log_level() < log_warnings) unit_test_log.set_threshold_level(log_successful_tests); }; ~GlobalConfig() { std::cout << "GlobalConfig teardown\n"; } }; BOOST_GLOBAL_FIXTURE(GlobalConfig); struct Fixture { Fixture() { BOOST_TEST_MESSAGE("setup Fixture"); using namespace boost::unit_test; unit_test_log.set_threshold_level(log_successful_tests); } ~Fixture() { BOOST_TEST_MESSAGE("teardown Fixture"); } }; #endif /* _GLOBALFIXTURE_HPP */* *I then link to boost_unit_test_framework-gcc34-mt-1_38.so The link passes , but I get a warning from gcc++ 3.4.4 that auto-linking has been enabled ( I will provide the exact details if useful ). I can execute the resulting mainTest.exe without problems, but the compiler warnings tells that something is not quite right. Is the above example the right way to use multiple test files ? Are the flags for shared libs correctly set ? Thanks for your help. PS: I think that Boost.Test is not easy to grasp ( at least for me ). I think this is partially due to a lack of complete examples ( involving for examples a test suite with more than one test file ). Also the static/shared library topic and the related macros ( BOOST_TEST_DYN_LINK etc ) could do with a concrete example. Maybe the mentioned case above could serve as an example after clarification. Peter

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[New Feature Suggestion] Dynamic exception handlers registration
by Alex Tkachenko 17 May '09

17 May '09

Hello there. A while back I wrote usefull tool for organizing exception handling. The general idea is borrowed from boost::execution_monitor (http://www.boost.org/doc/libs/1_38_0/libs/test/doc/html/execution-monitor.h…) . Similarly, I call this unit "Exception Monitor". It allows to dynamically register exception converters and convert exception objects from any source types to arbitrary target type. For instance, if you write some integration code which uses several external modules, and each of these modules could generate their own tree of exceptions, you would face serious issue trying to implement error diagnostic. One approach is to handle only base exception for each module and to catch them in function main(). Let's assume that all exceptions are inherited from std::exception, so we need to catch single base (std::exception). This approach is convenient but not precise. Even if we want just to output error message using std::exception::what() we have only some general low level error description, moreover this description could be completely wrong. It doesn't reflect actual cause of the error because at the place where the exception is originally generated it couldn't know about context of execution. On the contrary, we can catch low-level exceptions in the place where execution context is more obvious and convert it to some "application" exception which contains more information about current situation. This is the solution for detailed error diagnostic, but it is too tedious. Also such code is unscalable, error prone and hard to support. Look at the following example: /////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////// class app_error: public virtual std::exception { ... }; void foo() { try { ...local state... unit1::foo(...); unit2::foo(...); } catch(const unit1::exception1& ex) { //...convert caught exception to app_error using local state throw app_error(...); } catch(const unit1::exception2& ex) { //...convert caught exception to app_error using local state throw app_error(...); } catch(const unit2::exception& ex) { //...convert caught exception to app_error using local state throw app_error(...); } } int main() { try { foo(); } catch(const app_error& ex) { cout << "Error: " << ex.what() << endl; } catch(const std::exception& ex) { cout << "Unknown error: " << ex.what() << endl; } catch(...) { cout << "Unknown error" << endl; } } The main drawback of this source code is that exception handling is mixed with 'main' code. It would be better if we could write something like this: /////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////// class app_error: public virtual std::exception { ... }; typedef exc::catcher<app_error> app_catcher; //...exception catcher type typedef std::list<app_catcher> app_catchers; //...container for catchers struct convert_unit1_ex1 { const app_error operator()(const unit1::exception1&); }; struct convert_unit1_ex2 { const app_error operator()(const unit1::exception2&); }; struct convert_unit2_ex { const app_error operator()(const unit2::exception&); }; app_catchers excon; void foo() { ...local state... //...register catchers for possible exceptions excon.push_front( app_catcher::create<unit1::exception1>( convert_unit1_ex1(...local state...))); excon.push_front( app_catcher::create<unit1::exception2>( convert_unit1_ex2(...local state...))); excon.push_front( app_catcher::create<unit2::exception>( convert_unit2_ex(...local state...))); //... unit1::foo(); unit2::foo(); //...good idea is to use RAII to register catchers to avoid this //...manual deregistration: excon.pop_front(); excon.pop_front(); excon.pop_front(); } int main() { try { guard(excon, foo()); } catch(const app_error& ex) { cout << "Error: " << ex.what() << endl; } catch(const std::exception& ex) { cout << "Unknown error: " << ex.what() << endl; } catch(...) { cout << "Unknown error" << endl; } } Pluses of this technique: 1) it encourages developer to implement exception handlers code separatly from 'main' code; 2) it provides framework for detailed exception handling; 3) it offers flexible means for structural arrangement of exception handlers' source code. Very interesting feature of Exception Monitor is ability to sort catchers in "proper" order regarding their inheritance. So catcher for std::runtime_error should be earlier then std::exception. This is what functions exc::insert and exc::replace do. Library source code (it's tested it on gcc 4.3.1): #ifndef EXCEPTION_MONITOR_HEADER_GUARD #define EXCEPTION_MONITOR_HEADER_GUARD /* * Exception Monitor: * allowes dynamic exception handlers registration * Author: Alex Tkachenko * 2009.02.10 */ #include <cassert> #include <boost/function.hpp> #include <boost/static_assert.hpp> #include <boost/type_traits/is_base_of.hpp> #include <boost/shared_ptr.hpp> #include <typeinfo> namespace exc { namespace details { class failed_to_catch_exception {}; //... class try_catcher_base { public: virtual ~try_catcher_base() {} virtual void convert() const = 0; virtual void try_throw_self_exception() const = 0; virtual bool try_catch_self_exception( const try_catcher_base& other) const = 0; virtual const std::type_info& type() const = 0; }; template<typename Texception_to, typename Texception_from> class try_catcher: public try_catcher_base { typedef boost::function<const Texception_to (const Texception_from&)> converter_f; public: try_catcher(const converter_f& iconverter): converter(iconverter) { assert(!converter.empty() && "Null converter"); } private: void convert() const { try { throw; } catch(const Texception_from& ex) { throw converter(ex); } catch(...) { throw failed_to_catch_exception(); } } void try_throw_self_exception() const { throw (Texception_from*)0; } bool try_catch_self_exception(const try_catcher_base& other) const { try { other.try_throw_self_exception(); } catch(Texception_from*) { return true; } catch(...) { return false; } } const std::type_info& type() const { return typeid(Texception_from); } //... converter_f converter; }; }//...namespace details template<typename Texception_to> class catcher { typedef boost::shared_ptr<details::try_catcher_base> impl_t; catcher(const impl_t& iimpl): impl(iimpl) { assert(impl && "NULL catcher implementation"); } void convert() const { impl->convert(); } void try_throw_self_exception() const { impl->try_throw_self_exception(); } bool try_catch_self_exception(const catcher& other) const { return impl->try_catch_self_exception(*other.impl); } public: typedef Texception_to Texception_to_type; template<typename Texception_from> static const catcher create( const boost::function<const Texception_to (const Texception_from&)> converter) { //...it's senseless to convert from derived to base exception, //...or convert exception to its own type BOOST_STATIC_ASSERT( (!boost::is_base_of<Texception_to, Texception_from>::value)); return catcher( impl_t( new details::try_catcher<Texception_to, Texception_from>( converter))); } //... const std::type_info& type() const { return impl->type(); } void swap(catcher& rhs) { impl.swap(rhs.impl); } private: template<typename Treturn, typename Tcatchers> friend Treturn guard( const Tcatchers& catchers, const boost::function<Treturn ()>& func); template<typename TcatchersIterator> friend TcatchersIterator find( TcatchersIterator begin, TcatchersIterator end, const typename std::iterator_traits<TcatchersIterator>::value_type& catcher); //... impl_t impl; }; template<typename Treturn, typename Tcatchers> Treturn guard( const Tcatchers& catchers, const boost::function<Treturn ()>& func) { assert(!func.empty() && "Empty function"); typedef typename Tcatchers::value_type::Texception_to_type Texception_to_type; try { return func(); } catch(...) { const typename Tcatchers::const_iterator end(catchers.end()); for(typename Tcatchers::const_iterator iter(catchers.begin()); end != iter; ++iter) { try { iter->convert(); } catch(const Texception_to_type&) { throw; } catch(details::failed_to_catch_exception) { //...try next handler } } throw; } } template<typename Tcatchers> inline void guard( const Tcatchers& catchers, const boost::function<void ()>& func) { guard<void, Tcatchers>(catchers, func); } template<typename Texception_to> inline bool operator==( const catcher<Texception_to>& lhs, const catcher<Texception_to>& rhs) { return lhs.type() == rhs.type(); } template<typename Texception_to> inline bool operator!=( const catcher<Texception_to>& lhs, const catcher<Texception_to>& rhs) { return !(lhs == rhs); } template<typename Texception_to> inline void swap(catcher<Texception_to>& lhs, catcher<Texception_to>& rhs) { lhs.swap(rhs); } template<typename TcatchersIterator> TcatchersIterator find( TcatchersIterator begin, TcatchersIterator end, const typename std::iterator_traits<TcatchersIterator>::value_type& catcher) { for(;end != begin; ++begin) if(begin->try_catch_self_exception(catcher)) return begin; return end; } template<typename Tcatchers> void insert(Tcatchers& catchers, const typename Tcatchers::value_type& catcher) { typename Tcatchers::iterator iter( exc::find(catchers.begin(), catchers.end(), catcher)); catchers.insert(iter, catcher); } template<typename Tcatchers> void replace(Tcatchers& catchers, const typename Tcatchers::value_type& catcher) { typename Tcatchers::iterator iter( exc::find(catchers.begin(), catchers.end(), catcher)); if(catchers.end() == iter) catchers.push_back(catcher); else if(catcher == *iter) *iter = catcher; else catchers.insert(iter, catcher); } } //...namespace exc #endif /*EXCEPTION_MONITOR_HEADER_GUARD*/

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[test]
by Jochen Heckl 17 May '09

17 May '09

Hi, I think I stumbled over a problem in the boost unit test library. I'm running MSVC 2008 SP1. Maybe also worth mentioning is, that I use _HAS_TR1=0 with any msvc build. Also I compile boost using bjam define=_HAS_TR1=0 ... Well straight to the problem: this code (boost\test\utils\basic_cstring\basic_cstring.hpp, around line 170) template<typename CharT> inline basic_cstring<CharT>::basic_cstring( std_string const& s ) : m_begin( s.c_str() ) , m_end( m_begin + s.size() ) { } will result in a corrupted basic_cstring, if the source string s goes out of scope, which is the case here ( \boost\test\impl\unit_test_main.ipp, around line 179 ) ... int BOOST_TEST_DECL unit_test_main( init_unit_test_func init_func, int argc, char* argv[] ) { try { framework::init( init_func, argc, argv ); if( !runtime_config::test_to_run().is_empty() ) { test_case_filter filter( runtime_config::test_to_run() ); // <--- parameter will become corrupted traverse_test_tree( framework::master_test_suite().p_id, filter ); } ... because of the temporal std::string return from retrieve_parameter (boost\test\impl\unit_test_parameters.ipp, around line 353 ) const_string test_to_run() { return retrieve_parameter( TESTS_TO_RUN, s_cla_parser, s_empty ); } as quick and very very dirty fix I currently use: test_to_run() { static std::string TTR = retrieve_parameter( TESTS_TO_RUN, s_cla_parser, s_empty ); return TTR; } However, I would welcome, if somebody could supply a more suitable solutions. Best Jochen

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Re: [boost] [test] Automatic registration of tests created with BOOST_PARAM_TEST_CASE
by Jan Stolarek 17 May '09

17 May '09

> Here an example that works fine: Awsome, thanks. By the way, I just run into another serious problem, his time with BOOST_CHECK_EQUAL_COLLECTIONS macro that compares values in two collections. When using STL it is very common that elements in the collection are not objects, but pointers to objects. This leads to a serious problem, since people would rather want to compare values of objects that are pointed to, rather than pointer values (i.e. memory adresses). These will practically always be different, except the situation when two collections actually point to same addresses in memory. Now I'm trying to solve this problem. In test_tools.cpp I found : for( ; left_begin != left_end && right_begin != right_end; ++left_begin, ++right_begin, ++pos ) { if( *left_begin != *right_begin ) { res = false; res.message() << "\nMismatch in a position " << pos << ": " << *left_begin << " != " << *right_begin; } } I don't have the time at the moment, but I assume that replacing ( *left_begin != *right_begin ) with (**left_begin != **right_begin) would solve the problem? Jan

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[tuple] swap (also includes question about [sorting])
by Jeremiah Willcock 17 May '09

17 May '09

Thanks to Marcin Zalewski, the problem in my last email has been tracked down to the inability to swap boost::tuples that contain references. There have been a couple of proposals to add that: http://lists.boost.org/Archives/boost/2006/03/102603.php http://lists.boost.org/Archives/boost/2003/05/48488.php but it appears that none of them has made it into Boost. This feature is important because of sorting data structures using zip_iterators as in my previous message: http://www.nabble.com/-iterator--std::sort-on-zip_iterator-td23348384.html and the older posts: http://lists.boost.org/Archives/boost/2004/07/68758.php http://lists.boost.org/boost-users/2009/03/46623.php In particular, std::swap (from GCC 4.0.1) does not work correctly on the result of dereferencing a zip_iterator, which is a Boost tuple of references. The std::swap function does not work at all (fails at compile time) because the result of operator* is not a non-const reference, and std::iter_swap tries to use assignment between the tuples, producing incorrect answers at run time. Is it true that there is no standards-compliant way to solve this problem? If so, would that be a good justification for Boost.Sorting to include an algorithm similar to std::sort but that handles more generalized swappable types? -- Jeremiah Willcock

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[Boost.datetime] Serialization
by Sean Farrow 17 May '09

17 May '09

Hi: Would it be possible to add the funtion Given at the url: http://www.boost.org/doc/libs/1_39_0/doc/html/date_time/serialization.ht ml To the boost.datetime or boost.serialization library for 1.40. Cheers Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 4080 (20090515) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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[gsoc] Proposal for Generic Trie, Radix Tree, and Suffix Array Data Structures
by Chris Wagner 17 May '09

17 May '09

Hello, I am interested in writing a library consisting of generic implementations of several common data structures and algorithms primarily useful in text-processing. I believe these would be useful additions to Boost and would like to work on them for GSoC. Before I submit my proposal, I would like to hear whether or not the community agrees that this is a good idea, and I would appreciate any suggestions or comments offered. My plan is to implement a trie / prefix tree data structure, STL set/map-like classes implemented over the trie, a radix tree, a suffix tree implemented over the radix tree, and a suffix array. These would be instantiable over arbitrary sequence types, and use iterator traits to determine the contained type. I am a student at Kent State University, working on an M.S. in Computer Science in a combined undergraduate/graduate program. I have a particular interest in computational linguistics, and I will admit that am especially interested in this project because of how it could be applied to my own field, but I believe that these types would be of general utility to the programming community as a whole. Thank you for your time, Chris Wagner

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[futures] is there an updated version of futures
by Yigong Liu 16 May '09

16 May '09

Hello, Is there an updated version of futures lib by Anthony after the review? Is the one dated 20090530 still the latest one publicly avaialble? Thanks Yigong

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[exception] Virtual inheritance with no default constructors
by Adam Badura 16 May '09

16 May '09

The Boost.Exception library mandates that exceptions classes hierarchy should use virtual inheritance (http://www.boost.org/doc/libs/1_39_0/libs/exception/doc/using_virtual_inher…) The document notes that this does not go well with exceptions without default constructors ("(...) Note that virtual bases are initialized directly by the constructor of the most-derived-type (...)") however this should not be a concern as boost::exception provides other means to transport data. What is missing is however documentation that in normal circumstances boost::throw_exception cannot be used with exceptions types which have in their inheritance graph virtual base classes which are not default constructible. This is because boost::enable_current_exception constructs the clone_impl object which inherits the actual exception type and copy-constructs it. However this code will not compile if some base class of the callers exception type is virtual and non-default constructible. In my opinion few changes seem appropriate: 1) Note in the documentation explicitly this requirement (possibility of default construction). 2) Name an entity which should be made friend of exception class to use its non-public default constructor. This entity would be latter used by clone_impl. This way an exception could be default constructible only for this particular use case. 3) Provide means to late-initialize exception object. This would bypass the default construction problem (and goes well with private default constructor as described in 2)). 4) Allow to specify in boost::throw_exception (or similar places) not only the exception type but as well its (virtual) base types so that latter clone_impl could mention them on the initializers list as well and copy-construct them. (As far as I know there is no way of automatic detection of base types thus caller must specify them explicitly - however if I am mistaken such automation would be even better.) Adam Badura

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Re: [boost] [rfc] Unicode GSoC project
by Graham 16 May '09

16 May '09

>What kind of real-world use do people have for random access, anyways? >Even UTF-32 isn't random access for the things I can think of that >people would care about, what with combining codepoints and ligatures >and other such things. I wrote a couple of Unicode text editors that would have been a nightmare if they had not been operating on UTF-32. >As an aside, I'd like to see comparisons between compressed UTF-8 and >compressed UTF-16, since neither one is random-access anyways, and it >seems to me that caring about size of text before compression is about >as important as the performance of a program with the optimizer turned >off. Actually in a few cases I have seen it is not the compressed size but the conversion performance [memory/CPU] that hurts. It is much better to get the correct encoding for the correct use case. Yours, Graham

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Re: [boost] [rfc] Unicode GSoC project
by Graham 15 May '09

15 May '09

>I don't plan on supporting random access for UTF-16. >UTF-16 is still faster than UTF-8 because UTF-8 requires more complex >decoding. >UTF-16 has only two cases, making it easier to optimize branches under >the likely and unlikely case. Dear Mathias, Don't forget surrogates ! Yours, Graham

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Re: [boost] [rfc] Unicode GSoC project
by Graham 15 May '09

15 May '09

>I'll be reviewing it in a while. >I'm not too sure about the memory layout it uses (__uni_char_data could >really be compressed to use less memory for example), nor about the >interface it exposes, but it does seem to work well. >About is_grapheme_break though, isn't the implementation for legacy >grapheme cluster rather than extended ones though? Dear Mathias, The uni car data was laid out in that way for speed and simplicity. Please feel free to do it better. The grapheme break worked off the character attributes and standard rules. If it needs changing or did not cover a later standard, then it should be updated. The principle would not change as it makes the string iterators quite straightforwards.

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[rfc] Unicode GSoC project
by Mathias Gaunard 15 May '09

15 May '09

Hi everyone. I'm in charge of the Unicode Google Summer of Code project. I have been working on range adaptors to iterate over code points in an UTF-x string as well as converting back those code points to UTF-y for the past week and I stopped working on these for a bit to put together some short documentation (which is my first quickbook document, so it may not be very pretty). This is not a documentation of the final work, but rather that of what I'm working on at the moment. I would like to know everyone's opinion of the concepts I am defining, which assume the range that is being worked on is indeed a valid unicode range in a particular encoding, as well as the system used to enforce those concepts. Also, I put the normalization form C as part of the invariant, but maybe that should be something orthogonal. I personally don't think it's really useful for general-purpose text though. While the system doesn't provide conversion from other character sets, this can easily be added by using assume_utf32. For example, using an ISO-8859-1 string as input to assume_utf32 just works, since ISO-8859-1 is included verbatim into Unicode. The documentation contains as well some introductory Unicode material. You can find the documentation online here: http://mathias.gaunard.emi.u-bordeaux1.fr/unicode/doc/html/

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[C++0x] More config macros needed
by Beman Dawes 15 May '09

15 May '09

GCC 4.3 and even more so 4.4 have implemented significant portions of the C++0x core language, and provide lots of C++0x standard library components too. Microsoft 2010 beta 1 will ship "real soon", and it too will have some major C++0x core language features, and also some C++0x standard library components. Thus we need more config macros, particularly those aimed at the standard library. A possible approach: BOOST_NO_CONCEPTS // needed to tell if headers have been conceptized BOOST_NO_*_HDR // for each new C++0x header; * is name of header For example, BOOST_NO_CHRONO_HDR is defined unless header <chrono> is present. I'm proposing we not try to identify whether or no the header is complete. If BOOST_NO_CONCEPTS is defined, the header obviously hasn't been conceptized. Ditto anything else that depends on any other new core language feature that hasn't been implemented. Other incomplete aspects will have to be dealt with by testing the library version. We don't want feature macros to proliferate unduly; they are more work to create and maintain than you might think, and if there are a lot of them it gets very confusing. Comments? --Beman

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[Preprocessor] Can we generate token for #include programmatically ?
by Joel Falcou 15 May '09

15 May '09

Here is what I had in mind #define BASE foo.hpp #include BOOST_PP_STRINGIZE(BOOST_PP_CAT(nt2/support/numeric/functions/scalar/,BASE)) It fails because it seems we can't paste stuff ending with / ... Using fiel iteration, how can I circumvent hsi problem and generate a list of #include whose filename are computed from a sequence of name in a BOOST_PP_SEQ and a given, changing, prefix path ?

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Re: [boost] [rfc] Unicode GSoC project
by Graham 15 May '09

15 May '09

Dear Eric/ Mathias, >That's good, these are needed. Also needed are tables that store the various >character properties, and (hopefully) some parsers that build the tables >directly from the Unicode character database so we can easily rev it >whenever the database changes. A good reloadable character library is in the vault. >And UnicodeGrapheme concept doesn't make sense to me. You say, "A model of >UnicodeGrapheme is a range of Unicode code points that is a single grapheme >cluster in Normalized Form C." A grapheme cluster != Unicode code point. It >may be many code points representing a base character an many zero-width >combining characters. So what exactly is being traversed by a >UnicodeGrapheme range? >It is thus important to be able to apply algorithms with graphemes as the >unit rather than code points to deal with graphemes not representable by a >single code point. I think that a grapheme is more of an iterator concept than a data type concept. By specialising it you will unnecessarily complicate any library. Don't forget that, for example, the current grapheme may start as one character, then suddenly 'grab' the surrounding characters as it makes a combined glyph. I have never found a use case in practise where specialising the grapheme as other than a validated series of code points was helpful. The two cases where graphemes are important is in display [which requires intermediate glyph conversion anyway, and works just as well on runs of code points, so code points are fine] and in editing - and the grapheme-ness here alters during typing. >The Unicode standard also specifies various features such as a collation >algorithm in Technical Standard #10 - Unicode Collation Algorithm for >comparison and ordering of strings with a locale-specific criterion, as >well as mechanisms to iterate over words, sentences and lines Have a look at the character library that I posted in the vault - if you can do graphemes then you can do words, paragraphs etc as they are all just attributes of the characters with simple rules. Graphemes come in to their own for text display and editing and you would need these as well to be able to support that. Don't forget that windows GDI only supports point arithmetic and this means that you need to be able to locate word boundaries to display text well at different scales to work around the GDI scaling rounding [and GDI+ is not much better].

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[1.39.0] Beta candidate
by Beman Dawes 15 May '09

15 May '09

The beta candidate files are up at http://boost.cowic.de/rc/ Before pushing these out to SourceForge, it would be great if a few Boosters could download and try them out as a final QA check. Post your experiences here. Thanks, --Beman

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