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

bad include guards
by Steven Watanabe 26 Jan '17

26 Jan '17

AMDG The following pairs of files have identical include guards ./boost/concept_check/general.hpp ./boost/concept/detail/msvc.hpp ./boost/concept_check/msvc.hpp ./boost/concept/detail/msvc.hpp ./boost/filesystem/cerrno.hpp ./boost/cerrno.hpp ./boost/interprocess/containers/tree.hpp ./boost/interprocess/containers/detail/tree.hpp ./boost/mpl/min_max.hpp ./boost/mpl/max.hpp ./boost/mpl/vector/aux_/front.hpp ./boost/mpl/list/aux_/front.hpp ./boost/multi_index/identity_fwd.hpp ./boost/multi_index/identity.hpp ./boost/python/pointee.hpp ./boost/python/detail/pointee.hpp ./boost/spirit/phoenix/closures.hpp ./boost/lambda/closures.hpp ./boost/xpressive/proto/v1_/proto_typeof.hpp ./boost/xpressive/proto/proto_typeof.hpp ./libs/config/test/boost_no_dep_nested_class.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_mem_templates.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/config/test/boost_no_std_allocator.ipp ./libs/config/test/boost_has_vc6_mem_templ.ipp ./libs/conversion/test.hpp ./libs/any/test.hpp ./libs/interprocess/example/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/expand_bwd_test_template.hpp ./libs/interprocess/test/allocation_test_template.hpp ./libs/interprocess/test/printcontainer.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/interprocess/test/print_container.hpp ./libs/interprocess/example/printcontainer.hpp ./libs/iostreams/test/detail/utf8_codecvt_facet.hpp ./boost/detail/utf8_codecvt_facet.hpp ./libs/regex/test/regress/test_regex_search.hpp ./libs/regex/test/regress/test_partial_match.hpp ./libs/serialization/test/C.hpp ./libs/serialization/test/A.hpp ./libs/xpressive/perf/regex_comparison.hpp ./libs/regex/performance/regex_comparison.hpp ./tools/inspect/time_string.hpp ./tools/common/time_string.hpp In Christ, Steven Watanabe

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Why no non-null smart pointers?
by Ross MacGregor 29 Apr '14

29 Apr '14

I just created a very small smart pointer libary for our project. It will contain two types of shared pointers: SharedHandle and NullableSharedHandle. SharedHandle will be a shared pointer that cannot be null by ensuring a non-null construction while NullableSharedHandle will basically be a typedef for boost::shared_ptr. I firmly believe that code can be made more reliable by minimizing the use of nullable pointers. To this end, I think it is important that we start using non-null pointer types. Ideally the compiler would be able to understand a non-null pointer and catch bugs at compile time, but I think we can still improve things with a few runtime checks. If we make sure that a shared pointer is constructed with a non-null pointer and ban any reset() type methods, we guarentee that it points to something. This can be beneficial for the following reasons: 1. Any function that uses this type will no longer be burdened with precondition checks to make sure variables of this type are not null. 2. It's type is simply more explicit and better explains its function. 3. Moving the non-null check to the creation phase will reduce the possibility of encountering null pointer exceptions at runtime (assuming there are many more pointer references than constructor calls). So my little pointer library seems to make a lot of sense, but if so why hasn't this simple smart pointer variation made it into boost yet? Has this been discussed somewhere already? My search on non-null smart pointers is not revealing much discussion on the topic. Regards, Ross

9 16

[#pragma once]
by Sid Sacek 18 Nov '12

18 Nov '12

I've worked with the MSVC, Sun and GCC compilers. Each one of them supports #pragma once. Is there any reason to wrap this pragma within #ifdefs? Are there any compilers out there today that don't support this #pragma? #if defined( _MSC_VER ) && ( _MSC_VER >= 1020 ) # pragma once #endif Could we change this coding pattern so that it no longer looks like MSVC is being selfish? -Sid Sacek

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[interprocess] message_queue hangs when another process dies
by Sergei Politov 03 Nov '11

03 Nov '11

Hi, I have found the following problem with message_queue on win32 (MSVC 2008 + Windows Vista). Suppose we have 2 processes, one sends messages to queue, another reads them. When reading process dies (for instance using End process) during message_queue.receive the another process hangs in send. As I found during investigation, it tries to lock interprocess mutex, but it is already locked by dead process. So this message queue instance becomes unusable. I attached the example. Steps to reproduce: 1) Start "mq.exe s" (i.e. with argument s) It outs: sender: $PID 2) Start mq.exe without arguments. It outs: receiver: $PID 0 1 2 3 4 This time sender outs: send done: 3) At this point the message queue is empty and receiver waits for messages. End it with Task Manager. 4) Enter some number in sender console and press Enter. 5) The sender hangs in message_queue.send Best Regards, Sergei

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Re: [boost] [date_time] Time zone improvements
by Rutger ter Borg 25 May '11

25 May '11

Jeff Garland wrote: > Very cool :-) One question -- is there a portable solution where a user > could deploy a files onto a Windows system or is it a Unix only solution? > I'm fine with incorporating a *nix only solution because what your > suggesting will be a nice solution for *nix platforms, but it will need to > be clear that it's not portable. I don't see why it wouldn't be possible to deploy the (big-endian) binary files to any platform. Getting it into this binary form (using zone info compiler zic) may be harder to do cross-platform, but cygwin may help here. [snip] > As the primary maintainer of Boost date-time I can say with certainty that > there is interest in this functionality -- it's long been on my todo list > and I haven't had time to get to it. You can email me privately and we > can discuss all the details of how to get your code incorporated. I'll do! Regards, Rutger

5 9

[serialization] boost/serialization/path.hpp
by Johan Råde 21 Feb '11

21 Feb '11

There is no boost/serialization/path.hpp. I suggest the following: ---------------------------------------------------------------------------------------------------------------- #ifndef BOOST_SERIALIZATION_PATH_HPP #define BOOST_SERIALIZATION_PATH_HPP // MS compatible compilers support #pragma once #if defined(_MSC_VER) && (_MSC_VER >= 1020) #pragma once #endif #include <boost/config.hpp> #include <boost/filesystem/path.hpp> #include <boost/serialization/level.hpp> BOOST_CLASS_IMPLEMENTATION(boost::filesystem::path, boost::serialization::primitive_type) #ifndef BOOST_NO_STD_WSTRING BOOST_CLASS_IMPLEMENTATION(boost::filesystem::wpath, boost::serialization::primitive_type) #endif namespace boost { namespace serialization { template<class Archive, class String, class Traits> void serialize(Archive& ar, boost::filesystem::basic_path<String, Traits>& p, const unsigned int version) { String s; if(Archive::is_saving::value) s = p.string(); ar & boost::serialization::make_nvp("string", s); if(Archive::is_loading::value) p = s; } }} #endif //-------------------------------------------------------------------------------------------------------------- Comments? Any suggested improvements? --Johan Råde

5 11

[C++0x] Emulation of scoped enums
by Beman Dawes 16 Feb '11

16 Feb '11

The improved type safety of the C++0x scoped enum feature is attractive, so I'd like to start using it as it becomes available in compilers. See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a description. Note that the committee changed the name from strongly typed enums to scoped enums. See the attached for a boost/detail header that provides macro wrappers that use scoped enums if available, otherwise fall back on C++03 namespaces and unscoped enums. It lets a library write: BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END ... BOOST_SCOPED_ENUM(algae) sample( algae::red ); void func(BOOST_SCOPED_ENUM(algae)); and then a user can write: sample = algae::green; func( algae::cyan ); Comments or suggestions appreciated, --Beman // scoped_enum_emulation.hpp ---------------------------------------------------------// // Copyright Beman Dawes, 2009 // Distributed under the Boost Software License, Version 1.0. // See http://www.boost.org/LICENSE_1_0.txt // Generates C++0x scoped enums if the feature is present, otherwise emulates C++0x // scoped enums with C++03 namespaces and enums. The Boost.Config BOOST_NO_SCOPED_ENUMS // macro is used to detect feature support. // // Caution: only the syntax is emulated; the semantics are not emulated and // the syntax emulation doesn't include being able to specify the underlying type. // // See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf for a // description of the feature. Note that the committee changed the name from // strongly typed enums to scoped enums. // // Sample usage: // // BOOST_SCOPED_ENUM_START(algae) { green, red, cyan }; BOOST_SCOPED_ENUM_END // ... // BOOST_SCOPED_ENUM(algae) sample( algae::red ); // void foo( BOOST_SCOPED_ENUM(algae) color ); // ... // sample = algae::green; // foo( algae::cyan ); #ifndef BOOST_SCOPED_ENUM_EMULATION_HPP #define BOOST_SCOPED_ENUM_EMULATION_HPP #include <boost/config.hpp> #ifndef BOOST_NO_SCOPED_ENUMS # define BOOST_SCOPED_ENUM_START(name) enum class name # define BOOST_SCOPED_ENUM_END # define BOOST_SCOPED_ENUM(name) name #else # define BOOST_SCOPED_ENUM_START(name) namespace name { enum enum_t # define BOOST_SCOPED_ENUM_END } # define BOOST_SCOPED_ENUM(name) name::enum_t #endif #endif // BOOST_SCOPED_ENUM_EMULATION_HPP

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[process] How to run test cases
by Boris 23 Jan '11

23 Jan '11

As Boost.Process 0.3 has been released it would be great if the test cases are run on various platforms. So far I've tested Boost.Process on WinXP with MSVC 9.0, Cygwin with g++ 3.4.4 and Solaris with g++ 3.4.6 and Sun C++ 5.9. To make it as easy as possible for others to run the test cases here's a short description of how to proceed. Nearly all test cases depend on a program called "helpers". This program is built first and is started by many test cases as a child process. In order to find the program "helpers" the test cases must know its location. As there is no way to get the location at runtime it is hardcoded in the file libs/process/test/misc.hpp. As the location differs depending on what compiler is used YOU MUST CHECK FIRST THE PATH IN libs/process/test/misc.hpp! Otherwise most of the test cases will fail as they look for a program "helpers" in the wrong directory. As of today only those paths are correct and have been tested which are set for Windows, Cygwin and Solaris. Only after you have checked and maybe updated the path in libs/process/test/misc.hpp you should try to build and run the test cases: WinXP/MSVC 9.0 ************** With MSVC 9.0 you only need to open the Visual Studio 2008 Command Prompt, change to the directory with the test cases and run bjam: C:\boost_1_36_0\libs\process\test> ..\..\..\bjam.exe -q Cygwin/GCC 3.4.4 **************** On Cygwin it's important to know if the Boost libraries have been built for the POSIX or Windows API. By default Boost libraries on Cygwin use the Windows API. With the Windows API the Boost.Process test cases are not passed successfully though (there are compiler errors where I'm not sure currently if they are a Boost.Process problem and how they could be fixed). If you want to run the test cases on Cygwin you must (re-)build the Boost libraries to use the POSIX API: $ cd ~/boost_1_36_0 $ ./bjam cxxflags=-DBOOST_POSIX_API Afterwards you can run the test cases: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam cxxflags=-DBOOST_POSIX_API -q Solaris/GCC 3.4.6 ***************** At first you have to put the following line in ~/user-config.jam: using gcc : : : <linker-type>sun ; Then start building the Boost libraries: $ cd ~/boost_1_36_0 $ ./bjam --toolset=gcc cxxflags=-mcpu=ultrasparc For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. Afterwards the test cases can be run: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=gcc cxxflags=-mcpu=ultrasparc -q Solaris/Sun C++ 5.9 ******************* Build the Boost libraries with the sun toolset: $ cd ~/boost_1_36_0 $ ./bjam --toolset=sun stdlib=sun-stlport For the test cases to be passed successfully you must update Boost.Test. Change line 624 in ~/boost_1_36_0/boost/test/impl/execution_monitor.ipp temporarily to: - , m_CHLD_action( SIGCHLD, catch_system_errors, attach_dbg, alt_stack ) + , m_CHLD_action( SIGCHLD, false, attach_dbg, alt_stack ) It is important that the second parameter is false as the signal SIGCHLD should not be handled by the execution monitor and should not be reported as an error. If you run the test cases now you'll get this compiler error for one test case: "../../../boost/asio/detail/socket_ops.hpp", line 218: Error: Cannot assign void* to char*. "../../../boost/asio/detail/socket_ops.hpp", line 229: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 66: Error: Cannot assign void* to char*. "../../../boost/asio/detail/descriptor_ops.hpp", line 72: Error: Cannot assign void* to char*. The bug has been reported to the Boost.Asio mailing list. If you want to build that one test case, too, you need to fix the two files in Boost.Asio 1.36.0 yourself. All the test cases can be built and run with: $ cd ~/boost_1_36_0/libs/process/test $ ../../../bjam --toolset=sun stdlib=sun-stlport -q

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[asio] read_until -- possibly misleading documentation?
by Richard Smith 15 Apr '10

15 Apr '10

The documentation for Boost.ASIO (which is otherwise very comprehensive) says of the boost::asio::read_until set of overloads: | Read data into a streambuf until a delimiter is | encountered. <http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/reference/read_unt…> What the function actually does is to read blocks of data into the streambuf, and stop when the delimiter is found. This means that frequently data beyond the delimiter will be read into the streambuf. (And this is elaborated in more detail on the individual function's pages, if a reader looks there.) I appreciate that this behaviour is compatible with the documentation, but someone less familiar with ASIO could easily assume that the function will read as far as the delimiter and no further. (And I have just spent a fair amount of time debugging a piece of code where the author had made this assumption.) Could we change the summary documentation to read something like: | Read data into a streambuf at least until a delimiter is | encountered. The implementation may read beyond the | delimiter, but will not block when doing so. While I'm on the subject of ASIO documentation, I can't see any documentation on whether the service_name parameters to the basic_resolver_query constructors are allowed to be port numbers (e.g. "80") or whether they have to be symbolic names (e.g. "http"). Port numbers work, at least on Linux, but it's not clear whether this is something that I should be relying on. Similarly for IPv4 and IPv6 addresses in the host_name parameter. Richard Smith

3 2

[TypeTraits] is it possible to add something to boost.type_traits?
by frederic.bron＠alcan.com 17 Dec '09

17 Dec '09

Dear boost implementers, TypeTraits is very useful, thanks you. However, recently, I needed something to know if a type is comparable (with operator<) and that was not in the library. Fortunately, somebody forwarded me an earlier post on the users list where I could find what I wanted. The implementation was inspired from boost/detail/is_incrementable.hpp I have written is_less_comparable, is_less_equal_comparable, is_greater_comparable... inspired from the same source and I wonder if it could be possible to add it to the library as I think it could be helpful for others. I give the source code below (if it is useful) but I am not able to make it fully general as it is in boost/type_traits. In particular, I do not understand all the macros that are used. Regards, F. Bron (See attached file: is_comparable.hpp) Avis : Ce message et toute pièce jointe sont la propriété d'Alcan et sont destinés seulement aux personnes ou à l'entité à qui le message est adressé. Si vous avez reçu ce message par erreur, veuillez le détruire et en aviser l'expéditeur par courriel. Si vous n'êtes pas le destinataire du message, vous n'êtes pas autorisé à utiliser, à copier ou à divulguer le contenu du message ou ses pièces jointes en tout ou en partie. Notice: This message and any attachments are the property of Alcan and are intended solely for the named recipients or entity to whom this message is addressed. If you have received this message in error please inform the sender via e-mail and destroy the message. If you are not the intended recipient you are not allowed to use, copy or disclose the contents or attachments in whole or in part.

11 23

Re: [boost] Formal Review Request: Boost.String.Convert
by Vladimir.Batov＠wrsa.com.au 02 Dec '09

02 Dec '09

I understand we'll never manage to please everyone. Apologies. For now I am settling on the boost::convert interface as I very much agree with the arguments Robert's put forward for it and I feel there is the least disagreement around this interface. Surely boost::convert() has issues of its own. However, I feel the path (convert::to_string->convert::to->convert) how I myself arrived to this logical (IMHO) conclusion seemed reasonable. More so, despite its subtle (to some) directionality the interface has proven to work (as it is essentially the same interface as for lexical_cast). You cannot deny that I made considerable sacrifices (my pets "string" namespace and "to/from" are gone, something I was ready to die :-) for yesterday...). I am hoping the others could make some concessions as well and we would settle on boost::convert()... for now. If some other issues pop up that we missed so far, we'll revisit the issue. It is because I would very much like to move forward and start looking at the functionality and implementation. Do you think it is possible or I am rushing things again? I somewhat cleaned up the implementation (removed to/from, etc.). However, before going forward I'd like to discuss one important thing that's been bugging me since Scott brought it up. Namely, all conversions are now implemented as discriminated functions like // string-to-type conversion template<class TypeOut, class StringIn> typename boost::enable_if_c< !is_string<TypeOut>::value && is_string<StringIn>::value, detail::from_string<StringIn, TypeOut> >::type convert(StringIn const& from_str, TypeOut const& default_value =TypeOut()) { return detail::from_string<StringIn, TypeOut>(from_str, default_value); } However, Scott mentioned that and I feel that might be cleaner if we could implement it as namespace boost { template<class TypeOut, class TypeIn, class Enable =void> class convert; } Then for every conversion we'll be able to encapsulate *complete* implementation in the respective specialization class. Like for string-to-type template< class TypeOut, class StringIn, typename boost::enable_if_c< !is_string<TypeOut>::value && is_string<StringIn>::value, void>::type> class convert { convert(StringIn const& from_str, TypeOut const& default_value =TypeOut()); }; The reason I like it is that it eliminates other support/intermediate classes (like something used-to-called boost::string::value<...> and detail::from_string) and we can do int i = convert(str, -1); // Nothing changed. a 'convert' instance created on the stack and converted to 'int'. convert<int, string> checked(str, -1); // named 'convert' is created. convert<int, string> checked = convert(str, -1); // the same but some might like this syntax better. if (checked.good()) success // we can check the success as ussed to with boost::string::value It feels that approach gives us considerably more room for expansion as some special conversions will be able to have methods only specific to that particular conversion. For this approach to work with algorithms we'll need class convert { static TypeOut apply(TypeIn const&); }; and then std::transform( ints.begin(), ints.end(), std::back_inserter(strings), convert<string, int>::apply); Thanks, Vladimir.

9 63

[thread] #2742 Why the at_thread_exit cleanup function is const?
by vicente.botet 25 Nov '09

25 Nov '09

Hi, Anthony, could you verify the patch and test I have attached to the ticket works for other platforms that cygwin? Thanks, _____________________ Vicente Juan Botet Escribá

2 1

Boost.Variant is not EqualityComparable
by brook＠biology.nmsu.edu 12 Nov '09

12 Nov '09

I just ran into the case that Boost Variant does not satisfy the EqualityComparable concept. While it provides operator==() and operator<() (and therefore is LessThanComparable), it does not provide operator!=(), which is required for the EqualityComparable concept. Is this by design or oversight? It seems reasonable to expect that a Boost Variant model this concept, but perhaps I am missing something. In case it is by oversight, the following patch seems to provide the missing operator. Cheers, Brook --- boost/variant/variant.hpp.orig 2009-05-13 21:21:59.000000000 -0600 +++ boost/variant/variant.hpp 2009-05-25 19:21:40.000000000 -0600 @@ -1681,6 +1681,8 @@ return rhs.apply_visitor(visitor); } + bool operator!=(const variant& rhs) const { return !(*this == rhs); } + bool operator<(const variant& rhs) const { //

6 7

proposal interval container; ITL moved to the boost sandbox
by Joachim Faulhaber 11 Nov '09

11 Nov '09

Dear boosters, after completion of a lot of boostification work I moved my Interval Template Library to the boost sandbox in the boost project centric form: https://svn.boost.org/trac/boost/browser/sandbox/itl itl boost itl [itl_xt] [validate] libs itl [itl_xt] [validate] I have split up the original library into three parts: (1) itl, (2) itl_xt and (3) validate. Core part 1 'ITL' contains all interval container class templates. Only this part will be prepared for a formal submission. Part 2 'itl_xt' contains extended parts of the original library that do not belong to the core interval container data structures and might be proposed for later extensions. Part 3 'validate' contains the sources for the law based test automaton 'LaBatea' that has been used for an automated check of the ITLs correctness. Parts 2 and 3 do not yet conform boost standards and naming conventions and are not yet intended as contributions to boost. On the core ITL-part I have done the following: + Removed all virtual functions via introduction of mixins + Integrated deeper into boost libraries replacing own code by e.g. boost::type_traits and boost::mpl + Minimized the class template interfaces by transforming member functions into non member function templates. + Made interval containers more interoperable by overloading operators and global function templates. + Wrote a test suite using boost unit test tools. Tested for boost-instance types boost::date_time and boost::rational + Provided jamfiles to build and run examples and tests. + All examples and tests have been compiled, linked and run successfully with msvc_9.0 and gcc_3.4.4(cygwin). Next I am going to write boost style html-documentation. >From the boost web page I don't see a clear recommendation for a preferable way of doing that. Handcoded? Generated with BoostBook? Is there a reference library that has an exemplary standard documentation? Cheers Joachim

3 4

[utility] auto_buffer v2
by Thorsten Ottosen 07 Oct '09

07 Oct '09

Dear All, Hereby an updated class. Thanks to all who contributed with comments to the first try. I have made the following changes: 1. push_back() overloads are now growing 2. added swap() (boy, was this nasty to implement). I assume the allocator can be wapped without throwing. How do other people copy with this problem? 3. added copy-constructor + copy-assignment 4. made the min capacity equal to N, the number of elements in the stack buffer 5. the size of the internal buffer is now controlled via two policies: template< unsigned N > struct store_n_objects; template< unsigned N > struct store_n_bytes; the default is store_n_objects<256>. The reason is that we don't want the capacity to change just because we compile on a different platform. 6. added comparison operators Comments most welcome! best regards -Thorsten

4 7

[Endian] Version 0.10 available - Binary I/O added
by Beman Dawes 16 Sep '09

16 Sep '09

Version 0.10 of the Endian Integers library is available. Docs: http://mysite.verizon.net/beman/endian-0.10/libs/integer/doc/endian.html Zip: http://mysite.verizon.net/beman/endian-0.10.zip Sandbox: http://svn.boost.org/svn/boost/sandbox/endian This version adds binary I/O for both endian integers (<boost/integer/endian_binary_stream.hpp>) and C++ built-in types + std::string (<boost/integer/endian_binary_stream.hpp>). Support for C++0x features has also been added, ensuring that an Endian integer on C++0x is a POD. Comments appreciated! My Endian TODO list is pretty well cleared, so there are comments to the contrary, the library will be submitted for formal review in a few days. --Beman

3 4

[filesystem][spirit] problems with scoped enums with GCC 4.4 in C++0x mode
by Richard Webb 24 Jul '09

24 Jul '09

(forwarding from the Spirit list) As discussed in the thread @ http://www.nabble.com/-Spirit2--Regression-test-failures-on-GCC-4.4-in-C%2B…, the regression tests for Filesystem and Spirit 2 are pretty much all failing in GCC 4.4 in C++0x mode, due to problems with scoped enums and operator ==. Does anyone have any other ideas about the problem? Thanks, Richard Webb -- View this message in context: http://www.nabble.com/-filesystem--spirit--problems-with-scoped-enums-with-… Sent from the Boost - Dev mailing list archive at Nabble.com.

3 3

RFC: interest in Unicode codecs?
by Cory Nelson 23 Jul '09

23 Jul '09

Is there interest in having a Unicode codec library submitted to Boost? Here is what I have (only tested with GCC 4.3 on Debian, and VC++ 2008): http://svn.int64.org/viewvc/int64/snips/unicode.hpp Right now it is pretty simple to use: transcode<utf8, utf16le>(forwarditerator, forwarditeratorend, outputiterator, traits [, maximum]); transcode<wchar_encoding, utf32be>(inputrange, outputrange, traits [, maximum]); There is also a codecvt facet which supports any-to-any. Supports UTF-8, UTF-16, and UTF-32, in little or big endian. Has a special wchar_encoding that maps to UTF-16 or UTF-32 depending on your platform. A traits class controls error handling. -- Cory Nelson

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Re: [boost] RFC: interest in Unicode codecs?
by Graham 18 Jul '09

18 Jul '09

Dear Phil, >Having said all that, I must say that I actually use the code that I >wrote quite rarely. I now tend to use UTF8 everywhere and treat it as >a sequence of bytes. Because of the properties of UTF8 I find it's >rare to need to identify individual code points. For example, if I'm >scanning for a matching " or ) I can just look for the next matching >byte, without worrying about where the character boundaries are. Using UTF-8 can work well if you are only targeting American and Western Europe for non-literary use. If you need to support the rest of the world you really need to move to UTF-32 due to the large number of characters and the grapheme and glyph handling [e.g. in Urdu you can type 3 characters and they are displayed as a single combined glyph, and the cursor should never be placed between them]. Even in UTF-8 things can get a bit tricky. For example, where do you break the line if you needed in the middle of: joe)jack -> joe) <br> jack joe(jack -> joe <br> (jack joe+jack -> guess which is the standard ! For programmers we don't mind too much, but when you are writing text editors this can be really important. Now think how many characters there are with special rules on whether they can be split before, after, or never split, and you start to touch on the reason for the Unicode standard and why you need character properties. Yours, Graham

5 4

[convert] Now with Boost.Parameter interface.
by Vladimir.Batov＠wrsa.com.au 16 Jul '09

16 Jul '09

I've incorporated, uploaded to the Vault and started playing with the Boost.Parameter-based interface that Andrey Semashev was insisting from the set-go. And it is definitely growing on me and I like int i = convert<int>::from(str, 0)(locale_ = new_locale)(throw_ = true); instead of the original int i = convert<int>::from(str, 0) >> new_locale >> dothrow; I think people generally did not like locales and dothrow behaving like manipulators. The more I use the Boost.Parameter-based interface the more I am inclined to push it further and apply it to manipulators as well. I.e. int i = convert<int>::from(str)(radix_ = 16); instead of the original direct handling of std manipulators. int i = convert<int>::from(str) >> std::hex; Something, again, Andrey was advocating from the start. Now it feels like allowing io-stream manipulators exposes too much implementation detail and raises some unwarranted expectations. That raises a few questions that I am hoping people could help me with: 1. Both interfaces (for locale and dothrow) are currently supported: #1 int i = convert<int>::from(str, 0)(locale_ = new_locale)(throw_ = true); #2 int i = convert<int>::from(str, 0) >> new_locale >> dothrow; Should I remove #1? 2. Both interfaces #1 int i = convert<int>::from(str, 0) >> std::hex; #2 int i = convert<int>::from(str, 0)(radix_ = 16); are currently supported. Should I move away from direct manipulator support and remove #1? 3. I only managed to figure out how to supply only one Boost.Parameter at a time like int i = convert<int>::from(str, 0)(locale_ = new_locale)(throw_ = true); I understand how to achieve int i = convert<int>::from(str, 0)((locale_ = new_locale, throw_ = true)); (with double quotes) but do not want to go there as it looks somewhat unorthodox. I cannot figure out how to achieve the following int i = convert<int>::from(str, 0)(locale_ = new_locale, throw_ = true); (a list inside single quotes). I remember Andrey mentioning I could do that with a Boost.Parameter macro but I admit of not being bright enough to figure it out by myself. Any help would be greatly appreciated. Thanks, Vladimir.

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Re: [boost] gcc-4.4.0 and boost::optional is giving (spurious?) strict-aliasing warnings
by Giovanni Piero Deretta 15 Jul '09

15 Jul '09

On Thu, May 7, 2009 at 3:37 AM, Kim Barrett <kab.conundrums(a)verizon.net> wrote: > At 7:17 PM -0300 5/5/09, Brad Spencer wrote: >> > > In boost/aligned_storage.hpp, the class template > boost::aligned_storage defines its address member function thusly: > > void* address() { return this; } > const void* address() const { return this; } > I'm not 100% sure, but this could be very wrong as, IIRC, there is no guarantee that for non PODS the address of the first element (i.e. aligned_storage.data_) is the same as 'this'. but why doesn't aligned storage implements address() as: void * address { return this.data_.data_.buf; } BTW, I see that boost optional actually uses its own implementation of aligned storage, whose address member function returns a pointer to a char buffer, so it shouldn't be a problem. > There is code in boost/optional/optional.hpp (and probably the other > libs you mention) which looks like: > > internal_type* get_object() { > return static_cast<internal_type*>(m_storage.address()); > } > > What this leads, after some expansion, to something roughly equivalent > to > > static_cast<internal_type*>( > static_cast<void*>( > <a pointer to an instance of aligned_storage> )) > > which I believe is not strict aliasing safe. It is effectively a cast > from aligned_storage* to internal_type*, with a trip through void* > along the way. That trip through void* does not make the conversion > satisfy the strict aliasing rules. > IIRC aliasing rules talk about dynamic types of objects: roughly, you can access a memory location only with a type which is the same as the *dynamic type* of that location or as a char array. Boost optional does an explicit placement new of the stored type on the buffer which changes the dynamic type of the buffer so it should be safe from a standard point of view. Before reusing the buffer It invokes the destructor of the type, which ends the object lifetime. That said, gcc has been known to miscompile placement new from time to time (but it should be more or less fixed on recent versions: it pretty much acts as a compiler optimization barrier). In the end, IMHO the warning is spurious and could be safely ignored (modulo compiler bugs). > [Note that it is not the cast itself that violates the strict aliasing > rules, it is the later dereference of the pointer resulting from the > cast.] > > [Note that I'm pretty sure that switching from static_cast to > reinterpret_cast doesn't help.] > > One of the escape hatches provided by the strict aliasing rules > involves ensuring that there is a union type in scope at the point of > the conversion which contains both of the involved types. [The > "visible union" rule of 6.5.2.3#5.] I do not think this rule actually help you: you can't still read from a field different from the last written to (except for some exceptions like structures with common initial sequences.) Most compilers give additional guarantees, though. > Another escape hatch offered by the strict aliasing rules involves > memcpy and memmove. [6.5#6] I think that the following implementation of > aligned_storage::address will satisfy the strict aliasing rules: > > void* address() { > void* data = data_.data_.buf; > return memmove(data, data, sizeof(*data)); > } > > And I think gcc will optimize away the memmove, at least at sufficient > optimization levels. But note that I have not tested this at all. > > [Hm, using a size of 0 or 1 or some similar small value might be > sufficient to quiet the compiler; I'm not certain whether it is > sufficient to satisfy the letter of the C standard.] I do not see how this helps, first of all sizeof(*data) is illegal (sizeof(void) doesn't make any sense, gcc defines it as 1 as an extension), then how copying one byte will fix aliasing problems? > > The idea is that memmove (and memcpy, but that requres non-overlapping > source and destination, which we don't have here) is defined by the > aliasing rules to strip away the type of the destination, in a way > that a simple cast does not. I do not think it really strips away the type of the destination: in fact it is often unsed to bit cast from integers to float and back: if a memcpy(&some_float, &some_integer, sizeof(int32_t)) really did change the type of some_float, it would break a lot of code (you could no longer threat some_float as a float). What is guarateed is that some_float will contain the same bit pattern of some_integer, while still maintaining the float type. It assumes that the bit pattern of the source is a valid pattern for the destination type, otherwise it is UB. > > [And yes, I agree that this is rather grotesque.] > Aliasing rules really are a mess. -- gpd

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Mark throw_exception as noreturn?
by Andrey Semashev 05 Jul '09

05 Jul '09

Hi, I was wondering why the throw_exception function is not marked as noreturn? This makes it troublesome to use it as a drop-in replacement for throw statements as it starts to flag compiler warnings about missing return statements in non-void functions. I suggest to mark the function as noreturn at least for compilers that support it. GCC has __attribute__((noreturn)), MSVC has __declspec(noreturn).

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[Graph] iterator range splitting
by Tim Keitt 28 Jun '09

28 Jun '09

I've run into some problems with the Graph library as there is a lot of code that splits iterator ranges. An example of this is: (from depth_first_search.hpp) template <class VertexListGraph, class DFSVisitor, class ColorMap> void depth_first_search(const VertexListGraph& g, DFSVisitor vis, ColorMap color) { // // should the below not be: // graph_traits<VertexListGraph>::iterator vi, vend; // tie(vi, vend) = vertices(g); // if ( vi == vend ) ... ??? // or perhaps to be more terse // if ( empty_range(vertices(g)) ) // where empty_range(g) compares first and second // if (vertices(g).first == vertices(g).second) return; depth_first_search(g, vis, color, *vertices(g).first); } This is causing problems in my code where I have defined custom graph classes. In my case out_edges(g) != out_edges(g) because memory is allocated within the out_edges call and successive calls will return different ranges (vertex ranges are not a problem in my case as I use a simple counting iterator). Must out_edges(g) == out_edges(g) for a graph class to meet the Graph library requirements? If not, then a good bit of the code needs to be altered and possibly some of the iterator macros deprecated. Below I've located every instance where the first or second member of an iterator pair is thrown away. These cases are only problematic if the retained iterator is later compared to an iterator from another range. The fix is simple. One only needs to retain both members of the iterator pair. I am willing to provide a patch if it is agreed that the current code is wrong. THK egrep '(vertices|edges)$.*$\.(first|second)' * adjacency_list_io.hpp: for (vi = vertices(graph).first; vi != vertices(graph).second; ++vi){ adjacency_list_io.hpp: for (ei = edges(graph).first; ei != edges(graph).second; ++ei){ adjacency_list_io.hpp: for (vi = vertices(this->graph).first; vi != vertices(this->graph).second; ++vi){ adjacency_matrix.hpp: return *vertices(g).first; adjacency_matrix.hpp: return *vertices(g).first; adj_list_serialize.hpp: for (vi = vertices(graph).first; vi != vertices(graph).second; ++vi) { adj_list_serialize.hpp: for (ei = edges(graph).first; ei != edges(graph).second; ++ei){ bc_clustering.hpp: if (edges(g).first == edges(g).second) return; bc_clustering.hpp: edge_descriptor e = *max_element(edges(g).first, edges(g).second, cmp); bc_clustering.hpp: } while (!is_done && edges(g).first != edges(g).second); cuthill_mckee_ordering.hpp: if (vertices(G).first == vertices(G).second) cuthill_mckee_ordering.hpp: if (vertices(G).first == vertices(G).second) depth_first_search.hpp: if (start_vertex != implicit_cast<Vertex>(*vertices(g).first)){ vis.start_vertex(start_vertex, g); depth_first_search.hpp: if (vertices(g).first == vertices(g).second) depth_first_search.hpp: depth_first_search(g, vis, color, *vertices(g).first); depth_first_search.hpp: if (vertices(g).first == vertices(g).second) depth_first_search.hpp: *vertices(g).first), edge_connectivity.hpp: std::set_difference(vertices(g).first, vertices(g).second, edge_connectivity.hpp: std::set_difference(vertices(g).first, vertices(g).second, fruchterman_reingold.hpp: Dim minX = position[*vertices(g).first].x, maxX = minX; fruchterman_reingold.hpp: Dim minY = position[*vertices(g).first].y, maxY = minY; graph_test.hpp: bgl_first_9 = vertices(g).first, bgl_last_9 = vertices(g).second; graph_test.hpp: bgl_first_9 = vertices(g).first, bgl_last_9 = vertices(g).second; howard_cycle_ratio.hpp: if (boost::out_edges(vd1, m_g).first == boost::out_edges(vd1, m_g).second) throw bad_graph(m_vim[vd1]); howard_cycle_ratio.hpp: mcr_edge_t ed = *boost::out_edges(vd1, m_g).first; howard_cycle_ratio.hpp: good_vertex = boost::target(*boost::out_edges(good_vertex, m_pi_g).first, m_pi_g); howard_cycle_ratio.hpp: pi_edge_t tmp_ed = *(boost::out_edges(vd, m_pi_g).first); howard_cycle_ratio.hpp: remove_edge(*(out_edges(m_g2pi_g_vm[vd], m_pi_g).first), m_pi_g); is_kuratowski_subgraph.hpp: bipartition_start = next(next(next(vertices(K_3_3).first))); is_kuratowski_subgraph.hpp: si = vertices(contracted_graph).first; isomorphism.hpp: for (typename graph_traits<Graph1>::edge_iterator e1 = edges(g1).first; isomorphism.hpp: e1 != edges(g1).second; ++e1) { isomorphism.hpp: for (typename graph_traits<Graph2>::edge_iterator e2 = edges(g2).first; isomorphism.hpp: e2 != edges(g2).second && !found_edge; ++e2) { iteration_macros.hpp: bgl_first_9 = vertices(g).first, bgl_last_9 = vertices(g).second; iteration_macros.hpp: BGL_FIRST(__LINE__) = vertices(GNAME).first, BGL_LAST(__LINE__) = vertices(GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = vertices(GNAME).first, BGL_LAST(__LINE__) = vertices(GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = edges(GNAME).first, BGL_LAST(__LINE__) = edges(GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = edges(GNAME).first, BGL_LAST(__LINE__) = edges(GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = adjacent_vertices(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = adjacent_vertices(UNAME, GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = adjacent_vertices(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = adjacent_vertices(UNAME, GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = out_edges(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = out_edges(UNAME, GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = out_edges(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = out_edges(UNAME, GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = in_edges(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = in_edges(UNAME, GNAME).second; \ iteration_macros.hpp: BGL_FIRST(__LINE__) = in_edges(UNAME, GNAME).first,\ iteration_macros.hpp: BGL_LAST(__LINE__) = in_edges(UNAME, GNAME).second; \ johnson_all_pairs_shortest.hpp: typename Traits2::vertex_descriptor s = *vertices(g2).first; kamada_kawai_spring_layout.hpp: for (vertex_iterator ui = vertices(g).first, end = vertices(g).second; kamada_kawai_spring_layout.hpp: vertex_iterator ui, end = vertices(g).second; kamada_kawai_spring_layout.hpp: for (ui = vertices(g).first; ui != end; ++ui) { kamada_kawai_spring_layout.hpp: vertex_descriptor p = *vertices(g).first; kamada_kawai_spring_layout.hpp: for (ui = vertices(g).first; ui != end; ++ui) { kamada_kawai_spring_layout.hpp: for (ui = vertices(g).first; ui != end; ++ui) { kamada_kawai_spring_layout.hpp: for (ui = vertices(g).first; ui != end; ++ui) { kamada_kawai_spring_layout.hpp: for (ui = vertices(g).first; ui != end; ++ui) { king_ordering.hpp: if (vertices(G).first == vertices(G).second) king_ordering.hpp: if (vertices(G).first == vertices(G).second) metric_tsp_approx.hpp: Vertex v(*vertices(g).first); metric_tsp_approx.hpp: metric_tsp_approx_from_vertex(g, *vertices(g).first, metric_tsp_approx.hpp: metric_tsp_approx_from_vertex(g, *vertices(g).first, metric_tsp_approx.hpp: metric_tsp_approx_from_vertex(g, *vertices(g).first, metric_tsp_approx.hpp: metric_tsp_approx_from_vertex(g, *vertices(g).first, w, metric_tsp_approx.hpp: metric_tsp_approx_from_vertex(g, *vertices(g).first, w, id, vis); metric_tsp_approx.hpp: Tree t(mst, *vertices(mst).first, minimum_degree_ordering.hpp: adj_iter nu = adjacent_vertices(u_node, G).first; planar_canonical_ordering.hpp: vertex_t first_vertex = *vertices(g).first; prim_minimum_spanning_tree.hpp: choose_param(get_param(params, root_vertex_t()), *vertices(g).first), prim_minimum_spanning_tree.hpp: (g, *vertices(g).first, predecessor_map(p_map). property_iter_range.hpp: return std::make_pair(iter(vertices(graph).first, get(tag, graph)), property_iter_range.hpp: iter(vertices(graph).second, get(tag, graph))); property_iter_range.hpp: return std::make_pair(iter(vertices(graph).first, get(tag, graph)), property_iter_range.hpp: iter(vertices(graph).second, get(tag, graph))); property_iter_range.hpp: return std::make_pair(iter(edges(graph).first, get(tag, graph)), property_iter_range.hpp: iter(edges(graph).second, get(tag, graph))); property_iter_range.hpp: return std::make_pair(iter(edges(graph).first, get(tag, graph)), property_iter_range.hpp: iter(edges(graph).second, get(tag, graph))); push_relabel_max_flow.hpp: current(num_vertices(g_), out_edges(*vertices(g_).first, g_).second), push_relabel_max_flow.hpp: current[u] = out_edges(u, g).first; push_relabel_max_flow.hpp: current[v] = out_edges(v, g).first; push_relabel_max_flow.hpp: for (ai = current[u], ai_end = out_edges(u, g).second; push_relabel_max_flow.hpp: current[u] = out_edges(u, g).first; push_relabel_max_flow.hpp: for (; current[u] != out_edges(u, g).second; ++current[u]) { push_relabel_max_flow.hpp: if (current[u] == out_edges(u, g).second) { push_relabel_max_flow.hpp: ai = out_edges(u, g).first; push_relabel_max_flow.hpp: while (excess_flow[u] > 0 && ai != out_edges(u, g).second) { push_relabel_max_flow.hpp: ai = out_edges(u, g).first; random.hpp: i = vertices(g).first; random.hpp: return *vertices(g).first; random.hpp: i = edges(g).first; random.hpp: return *edges(g).first; sloan_ordering.hpp: s = *(vertices(G).first); undirected_dfs.hpp: if (start_vertex != *vertices(g).first){ vis.start_vertex(start_vertex, g); undirected_dfs.hpp: undirected_dfs(g, vis, vertex_color, edge_color, *vertices(g).first); undirected_dfs.hpp: *vertices(g).first), -- Timothy H. Keitt http://www.keittlab.org/

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How to speed up the djikstra graph
by Lennart Berg 23 Jun '09

23 Jun '09

Hi Everybody I have had the pleasure of using the boost graph library for my project now, but I have ran into some problems, that I hope you can guide me on. First of all, let me tell a little about the project. I am a third party developer for paradox interactive, making an expansion for one of their games. Now i have implemented the djikstra alghorithm to simulate the transport capacity of countries, and it works pretty well. However I still think that the speeds to be improved somewhat (takes about 1-2 secs to compute), to make it more playable. First of all the map consists of ~2500 provinces / vertexes each with 4-8 edges / neighbours. I Find all the provinces I can access and then add all neighbours from it as edges. Each edge is allocated a cost according to infrastructure, terrain and distance from orgin to destination. Each "round" of the game is an hour, so a day is effectively 24 rounds. Right now I make a new graph once every day, one separate graph for each country, and compute it for every country once a day. However as the game has up to 300+ countries that becomes a pretty harsh computational burden. Now pretty much every variable in this setup can change hourly. ( location of units, conquest / loss of provinces, destruction of infrastructure, expansion / repair of infrastructure) So the question is how I can improve this approach. Optimally the graph should be persistant and allow me to dynamically add / remove provinces and change the cost of the edges every hour (as I understand it the boost library allows that right now with vertex_clear / add etc.), and giving new values without recomputing every single edge in the graph 300 times every hour. Is that possible? And if how would that be done? Thanks in advance Lennart Berg

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Proposed addition to the iterator library for iterating over all tuples.
by Alex Mendes da Costa 19 Jun '09

19 Jun '09

Hi folks: I quite often have to write code to do the following: Given N sequences, generate all the N-tuples s.t. the i'th element in each tuple is drawn from the i'th sequence. For example, if sequence S1 is { 1, 2, 3 } and sequence S2 is { 10, 20 }, I need to generate these tuples: (1, 10), (2, 10), (1, 20), (2, 20). I think this problem could be solved elegantly with a iterator similar to zip_iterator. I have some questions: (1) Is there already a way to do this in boost? (2) If not, would this be a worthwhile addition to the iterator library? (3) If so, could I contribute code for this, or must the existing library owners write it? (4) If so, how would I go about getting my code added? Most of the docs seem to be about submitting entire libraries, rather than extensions to existing libraries. Thanks, Alex

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