February 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

5 8

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

[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

6 13

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

[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

4 9

[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

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

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

11 30

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

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).

4 6

[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/

6 16

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

4 18

[mpl] is there a or_seq like logical metafunction?
by vicente.botet 17 Jun '09

17 Jun '09

Hello, I needs calculate the mlp::or_ of a sequence of nullary logical metafunction. This seams quite simple. I have do the following: <code> template <typename Seq> struct or_seq; template <typename Seq, long N> struct or_seq_aux : mpl::or_< typename mpl::front<Seq>::type, or_seq<typename mpl::pop_front<Seq>::type> > {}; template <typename Seq> struct or_seq_aux<Seq, 1> : mpl::front<Seq>::type {}; template <typename Seq> struct or_seq : or_seq_aux<Seq, mpl::size<Seq>::value> {}; </code> Is there a boost or_seq like logical metafunction? Is there a better way to do it? I would be extremely interested in any suggestions. Best regards --------------------------- Vicente Juan Botet Escriba

5 34

[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*/

2 1

[RFC] thread::access_monitor
by Gregory Petrosyan 14 May '09

14 May '09

I would like to hear your comments on the idea behind access_monitor template, which ensures (at compile-time) that data, protected by it, can be accessed only with associated lock held. It can be useful when you want to expose all the native interface of your data type (STL container, for example): in such a case, using ordinary monitor pattern is almost impossible. Example usage: typedef access_monitor<data_type, mutex_type> data_access_monitor; void f(data_access_monitor const& d) { data_access_monitor::value_type const* data; data_access_monitor::lock_type lock; boost::tie(data, lock) = d.const_lock(); // do something with data here } Code: #include <boost/thread.hpp> #include <boost/tuple/tuple.hpp> template <typename T, typename Lockable> struct access_monitor { typedef T value_type; typedef boost::unique_lock<Lockable> lock_type; private: typedef boost::detail::thread_move_t<lock_type> lock_move_type; public: boost::tuple<value_type const*, lock_move_type> const_lock() const { lock_type lock(mutex_); return boost::make_tuple(&data_, lock.move()); } boost::tuple<value_type*, lock_move_type> lock() { lock_type lock(mutex_); return boost::make_tuple(&data_, lock.move()); } private: // mutex_ is guaranteed to be locked when you access data_ mutable Lockable mutex_; T data_; }; Sorry for draft-quality code (however, something like the above compiles with MSVC 9). Please CC me, because I am not subscribed. Gregory

2 1

[scope_exit] Boost.ScopeExit capturing 'this'
by adam.butcher＠selex-comms.com 11 May '09

11 May '09

I wasn't sure whether I had the correct address for Boost.ScopeExit's author Alexander Nasonov, so I've submitted to this list just in case and to get feedback from other users. I have been playing with BOOST_SCOPE_EXIT -- it it very convenient. One thing I would have liked would be to capture 'this' inside member functions. I have created a patch which adds BOOST_SCOPE_EXIT_THIS to do just that. It provides an operator->() in the generated struct which can be used to access the enclosing class's members. The syntax is: BOOST_SCOPE_EXIT_THIS( (&a) (&b) ) { a; b; // local captures (*this)->member; // member access } BOOST_SCOPE_EXIT_END; and can be BOOST_SCOPE_EXIT_THIS() { (*this)->member; } BOOST_SCOPE_EXIT_END; providing the preprocessor allows for empty parameter lists (which gcc does and vc does albeit after disabling a warning to remove noise). The type pointed to by the result of operator->() is correctly cv qualified. It has been tested on gcc 4.3, gcc 4.2, msvc 7.1 and msvc 9.0. I don't have access to other compilers. Boost.Typeof worked fine on gcc for typeof(this) -- mostly because gcc has a native typeof I guess. On visual studio (vc71 and vc90) it was not so good -- a compiler bug ( http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?Feedba… , http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?Feedba… ) that has been marked as 'Won't fix' means that 'this' cannot be used in expressions within template argument lists -- even if those expressions are innocuous typeid()s or sizeof()s for type-inference. The common workaround (capturing a compile-time integer with an enumerator and using the enumerator in the template parameter list) doesn't work with the vc71-specific implementation of Boost.Typeof since it is based on typeid() -- this cannot be captured in a compile-time expression (or I know of no way to that doesn't involve the expression existing in a template argument list). All is not lost though -- the general-purpose sizeof() based approach for the other VC versions works fine for VC71 for determining the typeof 'this'. As such my patch includes a VC>=1300 specific workaround for typeof 'this' determination. This is unfortunate but I couldn't think of any other non-intrusive way of doing it. Please find the attached patch and let me know what you think -- I'm sure this feature would be useful to users -- it saves having to do: TypeOfMyClassWhichCouldBeTedious* self = this BOOST_SCOPE_EXIT( (&self) ) { self->member; } BOOST_SCOPE_EXIT_END; which removes the convenience of BOOST_SCOPE_EXIT in these contexts since something like: struct at_end { TypeOfMyClassWhichCouldBeTedious* self; ~at_end() { self->member; } } at_end = {this}; can be done without any dependencies to achieve the same result. Regards, Adam. ------------------------------------------------------------ This email and any attached files contains company confidential information which may be legally privileged. It is intended only for the person(s) or entity to which it is addressed and solely for the purposes set forth therein. If you are not the intended recipient or have received this email in error please notify the sender by return, delete it from your system and destroy any local copies. It is strictly forbidden to use the information in this email including any attachment or part thereof including copying, disclosing, distributing, amending or using for any other purpose. In addition the sender excludes all liabilities (whether tortious or common law) for damage or breach arising or related to this email including but not limited to viruses and libel. SELEX Communications Limited is a Private Limited Company registered in England and Wales under Company Number 964533 and whose Registered Office is Lambda House, Christopher Martin Rd, Basildon, SS14 3EL. England.

4 8

Proposed templated integer_sort
by Steven Ross 25 Apr '09

25 Apr '09

Would there be interest in an integer_sort call that is faster than std::sort? Spreadsort is an in-place hybrid radix-based and comparison-based algorithm with better worst-case and average-case (roughly 20-50%) performance than introsort on random integer data. The worst-case advantage is algorithmic, with Spreadsort taking the better of O(n(square_root(bit_sizeof(data) - log(n)))) and O(nlog(n)) time. For 32-bit integers, that's O(n(square_root(32 - log(n)))), so for a log(n) of 16 (65536 items), it's 4n (plus a small constant times n), vs 16n for introsort. For larger n, the advantage vs. pure comparison-based algorithms increases. In effect, Spreadsort smoothly transitions from pure MSB Radix sort to std::sort with its data cut up by a couple iterations of MSB Radix sort (reducing the size of the log(n) factor), depending upon the distribution and size of the data. I could write a templated version of Spreadsort for the Boost library if there is interest. It would work for anything that supports the << and - operators. It could also handle standard floats sorted as integers. Functors supporting << and - could make it more general. Multi-dimensional sorting is also sped up by Spreadsort. I could also write a similar string_sort, that should also be significantly faster than std::sort. This would look much like postal sort, just using introsort after a certain number of iterations. Is this of interest? http://sourceforge.net/projects/spreadsort

15 118

Boost.Process 0.3 released
by Boris 14 Apr '09

14 Apr '09

I've released Boost.Process 0.3. Here's the documentation and a link to download the zip archive: Docs: http://www.highscore.de/boost/process/ Code: http://www.highscore.de/boost/process.zip It's a header-only library and thus pretty easy to use: Just copy the files to your Boost directory. In this release my main goal was to merge various snapshots: * There was my Boost.Process 0.2 version which was based on Boost.Process 0.1 from 2006. * There was a post-0.1 version of Boost.Process in SVN from 2007. * Chris Fairles had modified a Boost.Process snapshot for Unix platforms. * Ion Gaztañaga had also some ideas and bug fixes he sent to this mailing list recently. I just saw that Ilya Sokolov created another snapshot based on Boost.Process in SVN. That means we have again at least two different versions of Boost.Process. :-/ In my Boost.Process 0.3 version I concentrated on merging and overhauling code. I did not change the design but tried to make the code work: All the code which was written since 2006 should become usable. That's why I also concentrated a lot on test cases. There are quite a lot of test cases, and they all can be built and passed successfully on three platforms with four compilers. As it would be great if others run the test cases, too (ideally on new platforms), I'll send another message in a few minutes with a description how to run the test cases yourself. As the documentation was written in 2006 I also updated it. It's not yet really a good documentation: There are some files coming from 2006 while other files I wrote myself only last week. While the documentation can be improved it's at least up-to-date: The examples all work and can be compiled. As the documentation was not my priority for Boost.Process 0.3 it should be ok for now. Boris

9 14

[filesystem] Version 3 request for comments
by Beman Dawes 12 Apr '09

12 Apr '09

A prototype implementation of version 3 of Boost.Filesystem is available for comment. The critical feature of this prototype is the replacement of the class basic_path template with a single class path that supports both narrow and wide character paths. It also supports user supplied types, and will support the new C++0x char16_t and char32_t character types as compiler and standard library support becomes available. There is still a lot of additional work before V3 could be added to the trunk and eventually released. For example, work so far has concentrated on the new functionality, and ignored breaking changes to existing code. But enough stuff is working to make requesting comments useful. See http://svn.boost.org/svn/boost/sandbox/filesystem-v3/libs/filesystem/doc/v3… for a fuller description of the prototype and links to the prototype implementation. I've got some specific issues I'd like opinions on, but would first like to hear comments from anyone interested. --Beman

11 21

Final report of GSOC project 'Spatial Indexes'
by Federico J. Fernández 27 Mar '09

27 Mar '09

Hi List! I'm writing this email as a final report of my Google Summer of Code 2008 project for Boost. My project consist in adding some spatial indexing structures to Boost in the context of the Geometry proposal done by Barend Gehrels. Spatial indexes are data structures optimized for spatial oriented queries. The classic index structures (i.e. a binary tree) aren't spatially enabled, they have different ordering criteria but none of them relates to topological properties. The scope of these structures is really wide, from collision detection for games to geometry indexing for GIS software. The original project goals were: - Build a Quadtree. - Build an rTree. - Integrate some previous work from a former GSoC project of a k-d-tree. - Test and document everything. Both indexes are implemented now and everything is tested and documented. The only task that we didn't complete is the k-d-tree integration, because when we analyzed the code it was not ready, and we didn't have the time to finish it. About the results, we made several tests and benchmarks. We tested both indexes with 230.000 objects from GIS data to check the correctness of the implementation, and we made some benchmarks comparing the quadtree vs. rtree and comparing both of them to existing implementation (like GEOS) with very good results. We describe this benchmarks in the documentation offering this as a guide to choose the best index for each use. The code is still beta (or maybe alpha) and not recommended for production use because it is still not tested enough, but if you want to check the actual status you can find it in the following location: https://svn.boost.org/svn/boost/sandbox/SOC/2008/spacial_indexing/ And the docs are at: https://svn.boost.org/svn/boost/sandbox/SOC/2008/spacial_indexing/libs/spat… The future work now is huge. We have some ideas about integrating this in some way to multindexes, and we want to implement also a 'packed' version of the rtree to improve bulk-loading times among another things. Finally, I would like to thank to Boost for allowing me to be part of this year's SOC. And specially to my mentor Hartmut Kaiser for all his help during the program. -- federico j. fernandez

8 13

[endian] superfluous boost::operators<> ?
by Roland Schwarz 26 Mar '09

26 Mar '09

I discovered, that the following will not compile: unsigned u; ulittle32_t u1; ulittle32_t u2; u = 1; u1 = 1; u2 = u1 + u; The compiler complains about not being able to resolve similar conversions. My guess is, that using boost::operators<> _and_ providing type conversion operators at the same time is causing this. I think it should be enough to define the essential operators in cover_operators template, and omit boost::operators<> at all. At least I am not able to find any problems with this, since the compiler adjusts the arguments (using the provided type conversion operators?) and calls the built in operators, thereby resolving ambiguity. Any thoughts? -- _________________________________________ _ _ | Roland Schwarz |_)(_ | aka. speedsnail | \__) | mailto:roland.schwarz@chello.at ________| http://www.blackspace.at

2 1

[C++0x] The cpp0x branch has been merged into trunk
by Beman Dawes 21 Mar '09

21 Mar '09

The cpp0x branch has been merged into trunk, enabling a bunch of BOOST_NO_* macros for C++0x feature tests. This should have no impact on existing code, so be sure to let me know if it causes any problems. --Beman

7 19

[fusion] C++0x support?
by Ein Held 17 Mar '09

17 Mar '09

Hello is there any chance for c++0x support (rvalue forwarding for the containers' constructors and operator=s' in particular) for fusion in 1.39? If noone is up to adding support for this to fusion, my collegues and me would love to implement it. Thank you

5 10

Boost.Chrono where we are?
by vicente.botet 16 Mar '09

16 Mar '09

Hi, In November 2008, Beman said: "The Chrono library in the sandbox is now more-or-less feature complete." This library is esential to conform some boost libraries implementing standard libraries as Boost.Thread and Boost.Future as much as possible to the standard. It will be used also on the Boost.ThreasPool library and I would like also to use it on my AsynchronousExecutors library. Can we expect to have Boost.Chrono for review soon? Thanks, Vicente

1 1

request for discussion - yet another approach to automated memory management that solves the cycles problem and is very efficient
by Achilleas Margaritis 16 Mar '09

16 Mar '09

Dear boost members, The file 'mm2.zip' (in boost vault/memory) contains yet another solution for automatic memory management. The solution has the following attributes: 1) it solves the problem of cycles. 2) it releases resources deterministically. 3) it does not scan the graph of objects for reachability. It uses simple numeric values (i.e. keys) to determine if an object can be collected or not. The idea is very simple: pointers obtain keys during their construction (a simple global variable that is incremented). The key remains constant throughout the lifetime of a ptr. During pointer release, the pointers that point to an object are scanned: if there is no pointer that points to the object that has a lower key from the key of the releasing pointer, then the object can be deleted. The pointer semantics are normal C pointer semantics, except for the construction: the solution requires that pointers that are lvalues should obtain a key before the heap object that they will be assigned to. i.e. you can't do this: ptr p1 = new object; You have to do this: ptr p1; p1 = new object; All the operations have O(1) complexity, except the release operation, which has O(N) complexity, whereas N is the number of pointers that point to an object. Practically, the complexity is minimal, because it is rare to have that many different pointers to a single object (I think :-)). I have no idea if it works for all cases. The file 'main2.cpp' contains a lot of tests, which all pass. I have also included the benchmark of the Boehm GC modified to use my special ptr classes. In my machine, an Athlon 64 2.2 GHz, the benchmark is executed, using boost pools, at roughly 1900 milliseconds, whereas the Boehm gc benchmark, using the Boehm gc collector, is executed at roughly 1200 milliseconds (and the Java benchmark at roughly 600 milliseconds). The amazing thing is that it looks like it works, but I am not sure. I am sure there is a catch :-).

9 17

Re: [boost] [Boost-users] Maintenace Guidelines wiki page
by vicente.botet 15 Mar '09

15 Mar '09

----- Original Message ----- From: "Tomas Puverle" <Tomas.Puverle(a)morganstanley.com> To: <boost-users(a)lists.boost.org> Sent: Sunday, November 23, 2008 4:31 AM Subject: Re: [Boost-users] Maintenace Guidelines wiki page > >> I have started the Maintenace Guidelines wiki page. >> >> You can access it directly >> https://svn.boost.org/trac/boost/wiki/Guidelines/MaintenanceGuidelines >> >> or via https://svn.boost.org/trac/boost/wiki >> >> Guidelines >> * Maintenance Guidelines >> >> There page need to be completed and surely reworked but this is an starting >> point. >> >> Please be free to improve the page directly or post your comments or > suggestions to this list. >> >> Hopping this goes on the right direction, > > Vincente, > > A few ideas: How will you evaluate that your proposal is actually successful > and being followed by the boost developers? Hi, First this is proposal for guidelines. So people will be after all free to follow some of them or not. I'm expecting from people like you to improve it so it could be followed by more people. > Also, check out Daniel Walker's idea in the Boost.Range thread on boost.devel > about not having the engineers in charge of their own QA. Daniel Walker's idea " Perhaps a procedural solution that could avert this problem in the future is to quarantine the test cases. Authors can maintain commit privileges to their libraries on trunk, but only a select group of independent guardians have commit privileges to the test cases. That way there is a guarantee that libraries pass the same tests from one release to another. If an author would like to make a change that would break a test case, he or she would need to present the change to the list and submit a patch to the test case sentinels. This would be a fairly simple quality assurance protocol: engineers aren't allowed to do their own QA." This is already considered on the guidelines insome way. "Preserve the test from the preceding versions [author] The test from the preceding versions should not be changed when the author modifies its library. These not changed tests are a probe of compatibility with the preceding version. When these test must be changed they indicate a breaking user code issue. So instead of changing them add new ones stating explicitly on which version they were included. Old tests that should fail can be moved to the compile_fail or run_fail tests on the Jamfile. " The Daniel proposal implies some changes in the writing rights of the authors. I prefer to let this point out of these guidelines. Of course I think that this is a good idea. There is another guideline that could be used by the Boost comunity to check the author has not changed the old test cases. "Inspect announced modifications [author, user, RM] The use of the diff file will help to inspect that the modifications introduced have been correctly included on the documentation and a good test coverage has been done. This will result in a non official mini-review of the library. " I will add to check that the old testcases have not been changed. > Finally, please consider the idea of "core" and "new" release cycles, where the > components in "core" have much more stringent requirements on how and when they > are allowed to change. IMO this is out of the scope of the guidelines. Note that at the end it is up to the author to make the modification he/she consider pertinent. Could you send what you have in mind in the form of guidelines? > Finally, do you think it may have been better to start this thread on > boost.devel? I belived that i did it on both. I'm answering to both each time. Should I start a new thread including the guidelines contents? Vicente

14 46

[geometry] area, length, centroid, behavior
by Barend Gehrels 13 Mar '09

13 Mar '09

I would like to hear the opinion of potential geometry users on the list about the following. For the three geometries, point, linestring (= sequence of points), polygon: What should the generic "area" algorithm return for point and linestring? - 0 (zero) - compiler error (so this function is not defined for them at all) - exception Personally I would feel for 0 (zero) because you can then request the "area" in a generic collection, regardless of what is inside. What should the generic "length" algorithm return for polygon? - 0 (zero) - its perimeter - compiler error - exception What should the generic "centroid" algorithm return for point and linestring? - the point / the average its points - compiler error - exception and for an invalid polygon (e.g. no points at all, or not closed)? - exception - return "false" (if centroid is passed as a reference parameter) - ? (we've not always the compiler error option here because points are usually stored in a runtime collection) Thanks, Barend

15 66

Preview 4 of the Generic Geometry Library (ggl)
by Barend Gehrels 13 Mar '09

13 Mar '09

Dear list, It is a pleasure for us to present the fourth preview of the Generic Geometry Library. This time we've added the library to the SVN repository at boost, https://svn.boost.org/svn/boost/sandbox/ggl To store the library under a proper name, "ggl" is used, which stands for Generic Geometry Library. Before this we called it just Geometry Library, but we think Generic is appropriate from this version on. The first three previews were sent to this list in January, March and October 2008. Since then everything has been revised and reworked again, based on comments from the list. Thanks for all your comments! Concepts are now applied for all geometries. Algorithms now take any geometry fulfilling the concepts, and automatically take the right version of the underlying implementation. Ranges are now used instead of .begin()/end(). Tag dispatching is used instead of SFINAE. Transformations: previously these were just explained as an example, now transformations are included in the library, either to go from one coordinate system to another (for example from spherical to cartesian3D) or to translate/rotate/scale/map points from one Cartesian system to another, or otherwise. Map projections: included is an extensive addition with nearly 100 map projections. Those are not programmed by ourselves but automatically converted from C (PROJ4) into a our template-based approach, fitting with the geometry library, especially in the transformations explained above. License-wise this is possible. We're not sure about if this would fit in the Boost Library Collection, if there is interest in it, or that it might be "too much" for it, so we would be glad to hear your opinions. For more change descriptions, see the page on status and preview from the documentation (link below). The Generic Geometry Library is accessible from Boost SVN, mentioned above, or can be downloaded as well from http://geometrylibrary.geodan.nl Especially the examples, such as the custom point example and custom line string example show nicely how the library handles custom geometries and how they can be used inside the generic algorithms. We welcome any type of comment, opinion, cooperation, merge or join. Barend Gehrels, Amsterdam Bruno Lalande, Paris

3 11

[filesystem][cygwin] Standard conformance for wide characters
by Beman Dawes 11 Mar '09

11 Mar '09

I've decided not to attempt support for Cygwin in the next version of Boost.Filesystem. Cygwin's lack of library support for wchar_t is the problem . For the current Boost.Filesystem version (v2), the necessary workarounds are so pervasive that the implementation code is much harder to read and maintain. Witness the number of bug reports that are Cygwin specific. For v3, currently under development, trying to support Cygwin would be even harder, and would cause a serious delay in development. Plus I'm tired of waiting for the cygwin folks to come into full C++ conformance. IIUC, the reason Cygwin doesn't provide C++ standard library support for wchar_t is that the underlying C library is missing the C wchar_t functions. Perhaps Boosters who care about Cygwin could spearhead an effort to add the missing C support? The needed functionality isn't all that complex; the main problem might be just learning enough about how Cygwin/GCC is configured and built to be able to add a fairy small number of C functions. Thoughts? --Beman

10 29

Request for interest in the new Synchro library
by vicente.botet 10 Mar '09

10 Mar '09

Hi, I would like to know if the Boost community is interested in the Synchro library. Of course there is a lot of work to do, but I think that there is enough material to start a discussion on the approach. I'd appreciate it if people could take a look, test it on their compiler and give me some feedback. The library is available at Boost Sandbox: https://svn.boost.org/svn/boost/sandbox/synchro and Boost Vault: http://www.boostpro.com/vault/index.php?action=downloadfile&filename=synchr… that iIncludes every thing on the Sandbox + Html documentation Some examples use Boost.Interthreads also (available on the vault and the sandbox). This library is a compilation of what I have found in the literature not yet present in Boost. My main concern has been to boostify all these ideas in a coherent way. Next follows an overview of the library features: Boost.Synchro provides: * A uniform usage of Boost.Thread and Boost.Interprocess synchronization mechanisms based on lockables(mutexes) concepts and locker(guards) concepts. o lockables traits and lock generators, o lock adapters of the Boost.Thread and Boost.Interprocess lockable models, o locker adapters of the Boost.Thread and Boost.Interprocess lockers models, o complete them with the corresponding models for single-threaded programs: null_mutex and null_condition classes, o locking families, o semaphore, o condition_lockable lock which put together a lock and its associated conditions. * A coherent exception based timed lock approach, * A rich palette of lockers as o strict_locker, nested_strict_locker, o condition_locker, o reverse_locker, nested_reverse_locker, o locking_ptr, on_dereference_locking_ptr, o externally_locked, * A polymorphic lockable hierarchy. * High-level abstractions for handling more complicated synchronization problems, including o monitor for guaranteeing exclusive access to an object, and o a so-called rendezvous mechanism for handling direct communication between objects concurrent_components via ports using an accept-synchronize protocol based on the design of the concurrency library in the Beta language. On going work * array_locker and tuple_locker locker containers. * A complement to the already present in Boost.Thread lock, try_lock free functions: o lock_until, lock_for, try_lock_until, try_lock_for Best regrads, Vicente Juan Botet Escribá

3 12

wiki.boost.org Ancient
by Joel 09 Mar '09

09 Mar '09

Can wiki.boost.org be redirected to someplace useful? Right now it is an advertisement for crystal clear software. It is a bad advertisement since it is from 2005. Even worse, it has a link to a "boost wiki" that isn't being updated and has spam hidden away in it. It claims not to be official, but if the url is wiki.boost.org, it IS official! Thanks! Joel

4 6

[optional] little addition
by Arno Schödl 07 Mar '09

07 Mar '09

I just started using boost::optional, and this proved to be generically useful, but I believe is currently not in boost::optional: template< class T, class Tcompatible > bool optional_assign( T& t, boost::optional<Tcompatible> const& optt ) { if( optt ) { t=*optt; return true; } else { return false; } } so you can write boost::optional< TMyValue > TryToGetT(); T t; if( !optional_assign( t, TryToGetT () ) { ... other way to get t ... } instead of the more verbose: boost::optional< TMyValue > TryToGetT(); T t; boost::optional< TMyValue > const& optt=TryToGetT(); if( optt ) { t=*optt; } else { ... other way to get t ... } get_optional_value_or is similar, but the alternative must be an expression and is eagerly evaluated, both of which may be undesirable. Arno -- Dr. Arno Schoedl · aschoedl(a)think-cell.com Technical Director think-cell Software GmbH · Invalidenstr. 34 · 10115 Berlin, Germany http://www.think-cell.com · phone +49-30-666473-10 · toll-free (US) +1-800-891-8091 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl · Amtsgericht Charlottenburg, HRB 85229

4 23

[1.38.0] PDF package of Boost documentation released.
by John Maddock 07 Mar '09

07 Mar '09

Folks, A package containing PDF versions of Boost's documentation is now available for Boost-1.38.0 from the usual sourceforge download site: http://sourceforge.net/project/showfiles.php?group_id=7586&package_id=15971… Please note that due to the diverse range of tools in use within Boost it has not been possible to produce PDF's for all of Boost's libraries, those currently included as PDF's are: accumulators any array asio bimap range complex-tr1 concepts config conversion date_time foreach function hash interprocess intrusive iterator math-gcd math mpi octonion optional phoenix program_options proto python_tutorial quaternion ref regex scope_exit signals static_assert string_algo thread tr1 tribool type_traits typeof units unordered variant xpressive Documentation for the following tools are also included in this package: bjam boost_build boostbook quickbook Regards, John Maddock.

6 9

Formal Review: Boost.RangeEx
by Thorsten Ottosen 06 Mar '09

06 Mar '09

Dear Developers and Users, It's my pleasure to announce that the review of Neil Groves' RangeEx library starts today and lasts until March 3, 2009. What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

18 101

BGL question about districting
by Barend Gehrels 06 Mar '09

06 Mar '09

Hi, We're about an automated districting tool. We want to create Y districts from X polygons, all having a specific value (e.g. area or inhabitants), where the total value of each district is as similar as possible and each district is also as similar as possible. Let's call the value the "potential". Of course this problem is NP-hard so we're glad with the first solution or e.g. the first ten solutions. We thought to implement this by the Boost Graph Library. First we detect neighbour relations with our own Geometry Library (using the still-to-build "touches" relationship). We've a graph then and can divide the graph into subgraphs, each having connected nodes and an (nearly) equal "potential". I've some experience with BGL, having used the "connected_components". But I cannot find an appropriate algorithm for this problem, if it is available. Actually it even could be a "network flow" algorithm dividing the total potential by Y, and starting at some point flowing the potential through the graph. But all network flow algorithms seem to be on directed graphs. This is an undirected graph. It it is not possible with a standard BGL algorithm I think we can still solve it using BGL and e.g. breadth-sort-first, but just want to verify if it is possible or maybe by an unexpected workaround. Thanks, Barend

4 5

[time series] What happened to this library?
by Christian Henning 05 Mar '09

05 Mar '09

Hi there, as far as I can tell this lib has been approved but it doesn't show up in boost. Why is it not in there? Thanks, Christian

11 21

Design conventions; passing functors
by Joachim Faulhaber 04 Mar '09

04 Mar '09

Hi, I am pondering about functor passing. Functors occur in my library (ITL) e.g. for the aggregation of associated values on insertion in interval_maps (aggregation on overlap): template<class Domain, class Codomain, ...> class interval_map{ ... //(1) My current implementation is this: // Combinator is the aggregating functor template, // instantiated at compiletime template<template<class>class Combinator> interval_map& add(const value_type& value_pair) { /*Combinator template passed or instantiated somewhere*/ } ... } //I like this definition, because it's abstract: // The functor has to be a matching template e.g. inplace_max interval_map<int,int> m; m.add<inplace_max>(some); //(1) template<class Domain, class Codomain, ...> class interval_map{ //(2) The more traditional definition template<class Combinator> interval_map& add(const value_type& value_pair) { /*Combinator type passed or called somewhere*/ } ... m.add<inplace_max<int> >(some); //(2) I prefer (1) but both definitions (1) and (2) are purely static denotations. To have adaptable functors or functors that can have states, like in ... m.add(some, max_under(42)); ... I am afraid I have to say sayonara to definition (1) and use this instead: template<class Domain, class Codomain, ...> class interval_map{ //(3) Adaptable functor template<template<class>class Combinator> interval_map& add(const value_type& value_pair, const Combinator<Codomain>& combine) { /*combine functor passed or called somewhere*/ } Now, there seems to be a convention from the STL that functors shall be passed BY VALUE. template<template<class>class Combinator> interval_map& add(const value_type& value_pair, Combinator<Codomain> combine); This is stated in [Sutter & Alexandrecu 2005, C++ Coding Standards] item 89: "Function objects are modeled on function pointers. Like function pointers, the convention is to pass them by value. All of the standard algorithms pass objects by value, and your algorithms should too." I do not really understand this convention and feel some resistance to follow it. In addition the call by value implementation can (and will) lead to heavy inefficiency by unaware usage of fat functors. So I browsed through some boost libraries and found that functors are passed by reference there (e.g. accumulators, fusion). Final question: What is the boost standard on passing functors, that I can adapt to? Cheers Joachim

6 20

Re: [boost] [optional_io] InputStreamable refinement
by Andrew Troschinetz 04 Mar '09

04 Mar '09

Just heard back from Robert, I figure it's ok to forward this information: On Feb 26, 2009, at 10:00 AM, Robert Ramey wrote: > The serialization library does no depend up optional or it's > implementation. If you > change the implemenation of optional, just make the changes > are consistent with the requirements of the serialization library. > > The fact that the serialization of optional is implemented and tested > as part of the serialization library is an anomoly. In fact, this > code and test should be moved into the optional library. I checked the optional test in the serializable library and it doesn't seem to even include optional_io.hpp. And given Robert's comments, it seems like it would be ok to make changes to optional_io.hpp. With respect to the change I suggested for operator>>() (I think in my last post I typoed and wrote operator<<(), I always get those silly things backwards!): In the case where we fail to extract optional<T>::value_type, I'm not sure what would be the best thing to do with respect to the position of the get pointer or other state bits. I had suggested this: if (in.fail () && !in.eof ()) { in.clear (); in.get (); } The intent of calling get() there is to enable this use case: stringstream sin ("one 2 three 4 five 6"); optional<int> i; while (sin >> i) { if (i) cout << "found int: " << i << endl; } // which finds 2, 4, and 6 But why move the get pointer up by one? Why one? Does this make sense? I can't provide a reasoning as to why it does, if it does. So another possibility is this: if (in.fail () && !in.eof ()) { in.clear (); in.setstate (std::ios::eofbit); } This has the added benefit of of making the following possible w/o any code change to lexical_cast: // doesn't throw, returns 0 lexical_cast<optional<unsigned> > ("-1").get_value_or (0); And if it's well documented that extracting an uninitialized optional<T> sets the eofbit on the istream, then a prudent user could (if they really wanted to) reformulate the first use case as: stringstream sin ("one 2 three 4 five 6"); optional<int> i; while (sin >> i) { if (i) cout << "found int: " << i << endl; else { sin.clear (); sin.get (); } } This leaves the why of moving the get pointer up to the user, where I think it really belongs. Because I can image some use cases where you'd want to do something other than just call get(). For example, maybe you'd want to call getline() and ignore an entire line before trying to extract another optional<T>. Or maybe you'd want to read until you found some delimiter before trying again. -- Andrew Troschinetz Applied Research Laboratories

4 9

Re: [boost] An extension to boost::variant
by Catalytic 04 Mar '09

04 Mar '09

Chris Hamilton-3 wrote: > > While boost::variant is very capable at what it does, there is one thing > it doesn't do .. > > ..My question is this: why can't boost::variant be clever about reference > data types.. > > The reason I want this, is to have a nice String variant, that > encapsulates the various forms a string can take in a current project: > std::strings, char*'s, and std::string* and > boost::shared_ptr<std::string>. I want functions to be able to handle > all of these types transparently by using variants as the argument > types. Allowing "const std::string&" as a variant type allows this to > be done while not requiring a wasteful string copy. > .. > (I have a small custom variant class implementing this, and it appears > to work well. It's not as 'full fledged' as the boost::variant class, > but the approach I've taken could surely be grafted on to boost::variant.) > > An example will be better than a lengthy explanation, please have a look at the test-cases in the boost distribution: libs/variant/test/: specially variant_reference_test.cpp IMHO, it will answer all your queries. -Cat -- View this message in context: http://www.nabble.com/An-extension-to-boost%3A%3Avariant-tp21881442p2189668… Sent from the Boost - Dev mailing list archive at Nabble.com.

5 13

[convert] Default Syntax Idea
by Stewart, Robert 04 Mar '09

04 Mar '09

I was thinking a bit about syntax for the default value for the notional boost::convert() and kin. How about the following: int const i(3); string const s("something"); int const j(convert<int>(s) | 5); convert<DestType,SourceType>(SourceType) can return a type which throws on failure in operator DestType(), but has an operator |(SourceType) which returns a second type constructed with the SourceType value. The second type provides its own operator |(SourceType) which returns that value in its operator DestType() on failure. Returning a default value in lieu of an exception is a special case; it ought not be treated like formatting. Thus, while Boost.Parameter might be appropriate to package the extra information desired for formatting, I don't like the idea of writing "default_ = 5" in the call, and I don't think ", 5" in the argument list is as clear as it could be. The syntax above is obvious and concise while being distinct from whatever may be done for formatting. _____ Rob Stewart robert.stewart(a)sig.com Software Engineer, Core Software using std::disclaimer; Susquehanna International Group, LLP http://www.sig.com IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

9 32

boost::bind, problem with result type deduction and calling conventions
by Ingo.Loehken＠boc-eu.com 03 Mar '09

03 Mar '09

hi, anybody able to explain, why the code for the result type, related to special calling conventions defines an void return type ? template< class R, class T > struct add_cref< R (T::*) (), 1 > { typedef void type; }; so that code like class A { public: int __stdcall x() { return 0; } void const y() {} explicit A() { typedef boost::function<int()> fun_t; fun_t const f(boost::bind(&A::x,this)); } }; ends up with an warning at bind 1>G:\boost\boost_1_37_0\boost/bind.hpp(1643) : warning C4180: qualifier applied to function type has no meaning; ignored 1> G:\boost\boost_1_37_0\boost/bind.hpp(1682) : see reference to class template instantiation 'boost::_bi::add_cref<Pm,I>' being compiled 1> with 1> [ 1> Pm=int (__stdcall Ado::A::* )(void), 1> I=1 1> ] 1> G:\dev\workspace\files\ado\ado_bind.hxx(36) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 1> with 1> [ 1> Pm=int (__stdcall Ado::A::* )(void), 1> A1=Ado::A * 1> ] because the proposed specialization is not choosen by the compiler. Adding an __stdcall to the function signature type in add_cref fixes that problem, but still i do no understand, why the defintion is not like template< class M, class T > struct add_cref< M (__stdcall T::*) (), 1 > { typedef M const& type; }; and of course that fix is only applicable for __stdcall, where specialzations for other calling conventions can easily be generated, like for mem_fn_cc in respect to requested support for calling conventions. Thanks for your help, ILo. compiler : msvc 8.0 library : boost 1.38

2 1

[Review] Reminder: Boost.RangeEx review is going on
by Thorsten Ottosen 02 Mar '09

02 Mar '09

Dear Developers and Users, The review of Neil Groves' RangeEx library lasts until March 3, 2009. Please find the time to do a review if you are interested in this library. The discussion so far may be found here: http://archives.free.net.ph/message/20090220.122836.73bdbd04.en.html Below you will find a description of the library and information on how to write a review. best regards Thorsten, review manager What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

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N2346 - Defaulted and Deleted Functions emulation
by vicente.botet 02 Mar '09

02 Mar '09

Hi, is there an interest in a N2346 - Defaulted and Deleted Functions emulation http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2346.htm The idea been to use some macros that will use the =default, =delete if the compiler provides it and replace this macros by whatever has the same semantics. Alexandrescu introduced already two macros NON_ALIAS and NON_HEAP_ALLOCATED when talking about strict locks. Attached a draft for the default and deleted functions. Only one remark the macors must be used on the public part and without trailing ';', e.g. class X { BOOST_NEW_DELETE(X) Any coments are welcome, Vicente

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[geometry] gtl review pre-announcement
by Tom Brinkman 02 Mar '09

02 Mar '09

I'm doing a session at boostcon about GIL and making a bunch of examples, including some about GTL. You can include those as part of your unit test cases if you like. //Tom

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RPC library in the sandbox
by Jon Shuler 02 Mar '09

02 Mar '09

Does any know if the author(s) of this library are still around and plan to make any more updates to it? Jon

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[thread] static thread_specific_ptr?
by k-oli＠gmx.de 01 Mar '09

01 Mar '09

Hello, can I create an static thread specific pointer for class which will initalized by different threads? struct X { static thread_specific_ptr< U > tss_ptr_; }; in some threads: X::tss_ptr_.reset( new U); And for each thread X::tss_ptr_ will point to a different object in the freestore? Oliver

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rule cpp-pch unknown in module Jamfile</D:/boost/trunk/libs/math/build>?
by Peter Dimov 01 Mar '09

01 Mar '09

I'm trying and failing to run the smart_ptr tests because of: D:\boost\trunk\libs\smart_ptr\test>bjam ..\..\..\libs\math\build\Jamfile.v2:8: in modules.load rule cpp-pch unknown in module Jamfile</D:/boost/trunk/libs/math/build>. D:/boost/trunk/tools/build/v2/build\project.jam:313: in load-jamfile D:/boost/trunk/tools/build/v2/build\project.jam:62: in project.load D:/boost/trunk/tools/build/v2/build\project.jam:742: in project.use D:/boost/trunk/tools/build/v2/build\project.jam:89: in load-used-projects D:/boost/trunk/tools/build/v2/build\project.jam:73: in load D:/boost/trunk/tools/build/v2/build\project.jam:115: in load-parent D:/boost/trunk/tools/build/v2/build\project.jam:448: in initialize D:/boost/trunk/tools/build/v2/build\project.jam:303: in load-jamfile D:/boost/trunk/tools/build/v2/build\project.jam:62: in load D:/boost/trunk/tools/build/v2/build\project.jam:168: in project.find D:/boost/trunk/tools/build/v2\build-system.jam:535: in load D:\boost\trunk\tools\build\v2/kernel\modules.jam:283: in import D:\boost\trunk\tools\build\v2/kernel/bootstrap.jam:138: in boost-build D:\boost\trunk\boost-build.jam:17: in module scope -- Peter Dimov http://www.pdplayer.com

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